Document

Filed pursuant to Rule 424(b)(7)
Registration No. 333-240164
The information in this preliminary prospectus supplement and the accompanying prospectus is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and the selling stockholders are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.
Subject to completion, dated July 29, 2020
Preliminary prospectus supplement
(To prospectus dated July 29, 2020)
8,000,000 shares
https://cdn.kscope.io/9a241d7f4b299fba7b9afc7b82a057c8-tenablelogo1a.jpg
Tenable Holdings, Inc.
Common stock
The selling stockholders identified in this prospectus supplement are offering an aggregate of 8,000,000 shares of our common stock pursuant to this prospectus supplement and the accompanying prospectus. We will not receive any proceeds from the sale of shares of common stock by the selling stockholders.
Our common stock is listed on The Nasdaq Global Select Market under the symbol “TENB.” On July 28, 2020, the last reported sale price of our common stock as reported on The Nasdaq Global Select Market was $30.37 per share.
Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page S-6 of this prospectus supplement and on page 3 of the accompanying prospectus, as well as our other filings that are incorporated by reference into this prospectus supplement and the accompanying prospectus.
 
Per share
 
Total
Price to the public
$
 
$
Underwriting discounts and commissions(1)
$
 
$
Proceeds to the selling stockholders (before expenses)
$
 
$
(1)
We refer you to the “Underwriting” section beginning on page S-16 of this prospectus supplement for additional information regarding underwriter compensation.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
The underwriters may also purchase up to an additional 1,200,000 shares from the selling stockholders at the public offering price, less the underwriting discount, within 30 days from the date of this prospectus supplement.
We expect that delivery of the shares of common stock will be made to investors in book-entry form through The Depository Trust Company on or about August          , 2020.
J.P. Morgan
Morgan Stanley
Barclays
Prospectus supplement dated July          , 2020



TABLE OF CONTENTS
Prospectus supplement
Prospectus


S-i


We have not, and the selling stockholders have not, and the underwriters have not, authorized anyone to provide you with information different than or inconsistent with the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering. We, the selling stockholders, and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not, the selling stockholders are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents, regardless of the time of delivery of those respective documents. Our business, financial condition, results of operations, and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus supplement entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”
About this prospectus supplement
This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of common stock and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus dated July 29, 2020, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.
All references in this prospectus supplement and the accompanying prospectus to “Tenable,” “company,” “our,” “us,” and “we” or similar references refer to Tenable Holdings, Inc., a Delaware corporation, and, where appropriate, its consolidated subsidiaries, except where the context otherwise requires or as otherwise indicated.
“Tenable,” “Nessus,” “Tenable.io” and the Tenable logo, and other trademarks or service marks of Tenable Holdings, Inc. appearing in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein are the property of Tenable Holdings, Inc. These documents contains additional trade names, trademarks and service marks of others, which are the property of their respective owners. Solely for convenience, trademarks and trade names referred to in this prospectus supplement and the accompanying prospectus may appear without the ® or symbols.


S-ii


Prospectus supplement summary
This summary highlights certain information about us, this offering, and selected information contained elsewhere in or incorporated by reference into this prospectus supplement. This summary is not complete and does not contain all of the information you should consider before deciding whether to invest in our common stock. For a more complete understanding of our company and this offering, you should read and consider carefully the more detailed information included or incorporated by reference in this prospectus supplement and the accompanying prospectus, including the factors described under the heading “Risk Factors” of this prospectus supplement, in our Annual Report on Form 10-K filed with the SEC on February 28, 2020, in our Quarterly Report on Form 10-Q filed with the SEC on May 7, 2020 and in our other filings that are incorporated by reference into this prospectus supplement and the accompanying prospectus, as well as the information included in any free writing prospectus that we have authorized for use in connection with this offering.
Overview
We are a leading provider of solutions for a new category of cybersecurity that we call Cyber Exposure. Cyber Exposure is a discipline for managing, measuring and comparing cybersecurity risk in the digital era. Our enterprise platform enables broad visibility into an organization’s cyber exposure across the modern attack surface and deep insights that help organizations translate vulnerability data into business insights to understand and reduce their cybersecurity risk.
Our enterprise platform offerings include Tenable.io, which is our software as a service, or SaaS, offering and Tenable.sc, which is our on-premises offering, both of which provide organizations with applications purpose-built for areas of both traditional and modern attack surfaces, including IT infrastructure and applications, cloud environments and industrial Internet of things, or IoT, and operational technology, or OT, environments. These applications are designed with views, workflows and dashboards to help identify vulnerabilities, internal and regulatory compliance violations, misconfigurations and other cybersecurity issues, prioritize these issues for remediation, and provide insightful remediation guidance.
Our enterprise platform offerings are primarily sold on a subscription basis with a one-year term. Our subscription terms are generally not longer than three years. These offerings are typically prepaid in advance. To a lesser extent, we generate ratably recognizable revenue from perpetual licenses and from the related ongoing maintenance.
We sell and market our products and services through our field sales force that works closely with our channel partners, which includes a network of distributors and resellers, in developing sales opportunities. We use a two-tiered channel model whereby we sell our enterprise platform offerings to our distributors, which in turn sell to our resellers, which then sell to end users, which we call customers.
Many of our enterprise platform customers initially use either our free or paid version of Nessus, one of the industry’s most widely deployed vulnerability assessment solutions. Nessus, which is the technology that underpins our enterprise platform offerings, is designed to quickly and accurately identify vulnerabilities, configuration and compliance issues and malware. Our free version of Nessus, Nessus Essentials, allows for vulnerability assessment over a limited number of IP addresses. We believe many of our Nessus customers begin with Nessus Essentials and subsequently upgrade to Nessus Professional, the paid version of Nessus; however, we expect many users to continue to use Nessus Essentials.
Corporate information
Tenable Network Security, Inc., our predecessor, was incorporated under the laws of the State of Delaware in 2002. Tenable Holdings, Inc. was incorporated in Delaware in October 2015, and in November 2015, Tenable Network Security, Inc. was merged into our wholly-owned indirect subsidiary and in 2017 was renamed as Tenable, Inc. 

S-1


Our principal executive offices are located at 7021 Columbia Gateway Drive, Suite 500, Columbia, Maryland 21046. Our telephone number is (410) 872-0555. Our website address is www.tenable.com. The information contained on, or that can be accessed through, our website is not incorporated by reference into this prospectus supplement, and you should not consider any information contained on, or that can be accessed through, our website as part of this prospectus supplement or in deciding whether to purchase our common stock.

S-2


The offering
Common stock offered by the selling stockholders
8,000,000 shares
 
 
Option to purchase additional shares
The underwriters have been granted an option to purchase up to an aggregate of 1,200,000 shares of our common stock from the selling stockholders. This option is exercisable, in whole or in part, for a period of 30 days following the date of this prospectus supplement.
 
 
Common stock to be outstanding immediately after this offering
101,127,150 shares
 
 
Use of proceeds
We will not receive any of the proceeds from the sale of common stock offered by the selling stockholders. See “Use of Proceeds.”
 
 
Nasdaq Global Select Market symbol
“TENB”
 
 
Risk factors
Investing in our common stock involves a high degree of risk. See “Risk Factors” in this prospectus supplement and the sections captioned “Risk Factors” contained in our Annual Report on Form 10-K filed with the SEC on February 28, 2020, in our Quarterly Report on Form 10-Q filed with the SEC on May 7, 2020 and in our other filings that are incorporated by reference in this prospectus supplement and the accompanying prospectus.
The number of shares of our common stock to be outstanding immediately after this offering as shown above is based on 101,127,150 shares of common stock outstanding as of June 30, 2020 and excludes:
11,058,465 shares of common stock issuable upon the exercise of options outstanding at a weighted-average exercise price of $8.53 per share;
5,435,615 shares of common stock issuable upon the vesting of outstanding restricted stock units granted under our 2018 Equity Incentive Plan;
17,500,941 shares of common stock reserved for future issuance under our 2018 Equity Incentive Plan; and
5,721,517 shares of common stock reserved for future issuance under our 2018 Employee Stock Purchase Plan.
Unless otherwise indicated, all information in this prospectus supplement assumes no exercise of the outstanding options described above after June 30, 2020, no settlement of restricted stock units described above after June 30, 2020 and no exercise by the underwriters of their option to purchase additional shares of our common stock.


S-3


Summary consolidated financial data
The following tables summarize our consolidated financial data. We derived the summary consolidated statements of operations data for the years ended December 31, 2017, 2018 and 2019 from our audited consolidated financial statements incorporated by reference in this prospectus supplement and the accompanying prospectus. Our unaudited interim consolidated statement of operations data for the six months ended June 30, 2020 and 2019 and our unaudited consolidated balance sheet data as of June 30, 2020, each presented below, have been prepared on the same basis as our audited consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal, recurring nature that are necessary for a fair presentation of our unaudited interim consolidated financial statements. Our historical results are not necessarily indicative of the results to be expected in the future, and our operating results for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the entire year ending December 31, 2020.
When you read this summary consolidated financial data, it is important that you read it together with the historical consolidated financial statements and related notes to those statements, as well as “Management’s Discussion and Analysis of Financial Condition and Results of Operations” that are incorporated by reference into this prospectus supplement and the accompanying prospectus.
 
Year Ended December 31,
 
Six Months Ended June 30,
 
2017
 
2018
 
2019
 
2019
 
2020
 
(in thousands, except per share data)
Consolidated Statements of Operations Data:
 
 
 
 
 
 
 
 
 
Revenue
$
187,727

 
$
267,360

 
$
354,586

 
$
165,685

 
$
209,857

Cost of revenue(1)
25,588

 
43,167

 
60,818

 
27,144

 
37,843

Gross profit
162,139

 
224,193

 
293,768

 
138,541

 
172,014

Operating expenses:
 
 
 
 
 
 
 
 
 
Sales and marketing(1)
116,299

 
173,344

 
228,035

 
108,704

 
115,298

Research and development(1)
57,673

 
76,698

 
87,064

 
43,633

 
52,141

General and administrative(1)
28,927

 
46,732

 
69,468

 
31,123

 
36,812

Total operating expenses
202,899

 
296,774

 
384,567

 
183,460

 
204,251

Loss from operations
(40,760
)
 
(72,581
)
 
(90,799
)
 
(44,919
)
 
(32,237
)
Interest (expense) income, net
(75
)
 
2,355

 
5,830

 
3,150

 
1,189

Other expense, net
(16
)
 
(931
)
 
(680
)
 
(336
)
 
(1,258
)
Loss before income taxes
(40,851
)
 
(71,157
)
 
(85,649
)
 
(42,105
)
 
(32,306
)
Provision for income taxes
171

 
2,364

 
13,364

 
963

 
2,631

Net loss
(41,022
)
 
(73,521
)
 
(99,013
)
 
(43,068
)
 
(34,937
)
Accretion of Series A and B redeemable convertible preferred stock
(763
)
 
(434
)
 

 

 

Net loss attributable to common stockholders
$
(41,785
)
 
$
(73,955
)
 
$
(99,013
)
 
$
(43,068
)
 
$
(34,937
)
Net loss per share attributable to common stockholders, basic and diluted
$
(1.88
)
 
$
(1.38
)
 
$
(1.03
)
 
$
(0.45
)
 
$
(0.35
)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted
22,211

 
53,669

 
96,014

 
94,785

 
99,532

 
 
 
 
 
 
 
 
 
 

S-4


(1)
Includes stock-based compensation as follows:
 
Year Ended December 31,
 
Six Months Ended June 30,
 
2017
 
2018
 
2019
 
2019
 
2020
 
(in thousands)
Cost of revenue
$
281

 
$
1,707

 
$
2,817

 
$
1,394

 
$
1,577

Sales and marketing
1,579

 
6,911

 
16,032

 
7,581

 
9,871

Research and development
1,782

 
5,804

 
8,911

 
4,471

 
6,841

General and administrative
4,118

 
8,453

 
15,683

 
7,246

 
10,412

Total stock-based compensation
$
7,760

 
$
22,875

 
$
43,443

 
$
20,692

 
$
28,701

 
 
 
 
 
 
 
 
 
 
 
As of June 30, 2020
 
(unaudited)
(in thousands)
Consolidated Balance Sheet Data:
 
Cash, cash equivalents and short-term investments
$
242,101

Working capital
59,020

Total assets
575,836

Deferred revenue, current and non-current
365,309

Accumulated deficit
(600,058)

Total stockholders’ equity
111,168

 
 


S-5


Risk factors
Investing in our common stock involves a high degree of risk. Before deciding whether to invest in our common stock, you should consider carefully the risks described below and discussed under the section captioned “Risk Factors” contained in our Annual Report on Form 10-K filed with the SEC on February 28, 2020, in our Quarterly Report on Form 10-Q filed with the SEC on May 7, 2020 and in our other filings that are incorporated by reference in this prospectus supplement and the accompanying prospectus in its entirety, together with the other information in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference, and in any free writing prospectus that we have authorized for use in connection with this offering. If any of these risks actually occur, our business, financial condition, results of operations, or prospects could be seriously harmed. This could cause the trading price of our common stock to decline, resulting in a loss of all or part of your investment.
As disclosed in our Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2020 under the section titled “Risk Factors”, our business and results of operations may be negatively affected by the COVID-19 pandemic.  In addition, to the extent the ongoing COVID-19 pandemic adversely affects our business and results of operations, it may also have the effect of heightening many of the other risks and uncertainties described in the “Risk Factors” section in our Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2020, which may materially and adversely affect our business and results of operations.

S-6


Special note regarding forward-looking statements
Statements contained in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference, and any free writing prospectus that we have authorized for use in connection with this offering that are not strictly historical in nature are forward-looking statements within the meaning of Section 27A of the Securities Act, and within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These statements relate to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These forward-looking statements are subject to the “safe harbor” created by Section 27A of the Securities Act and Section 21E of the Exchange Act and may include, but are not limited to, statements about:
the anticipated impact of the global economic uncertainty and financial market conditions caused by the COVID-19 pandemic on our business, results of operations and financial condition, including on our sales and our revenue growth rate;
our market opportunity;
the effects of increased competition as well as innovations by new and existing competitors in our market;
our ability to adapt to technological change, release new products and product features and effectively enhance, innovate and scale our enterprise platform and solutions;
our ability to effectively manage or sustain our growth and to achieve profitability;
our ability to maintain and expand our customer base, including by attracting new customers;
our relationships with third parties, including channel partners;
completed and potential acquisitions and integration of complementary businesses and technologies;
our ability to maintain, or strengthen awareness of, our brand;
perceived or actual problems with the security, integrity, reliability, compatibility and quality of our platform and solutions;
future revenue, hiring plans, expenses, capital expenditures, capital requirements and stock performance;
our ability to attract and retain qualified employees and key personnel and further expand our overall headcount;
our ability to stay abreast of new or modified laws and regulations that currently apply or become applicable to our business both in the United States and internationally;
our ability to maintain, protect and enhance our intellectual property;
costs associated with defending intellectual property infringement and other claims; and
the future trading prices of our common stock and the impact of securities analysts’ reports on these prices.
In some cases, you can identify forward-looking statements by terms such as “anticipates,” “believes,” “could,” “estimates,” “expects,” “goal,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would,” the negative of these words and words or similar expressions intended to identify forward-looking statements. These statements reflect our views as of the date on which they were made with respect to future events and are based on assumptions and subject to risks and uncertainties. The

S-7


underlying information and expectations are likely to change over time. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date the statement is made, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.
Given these uncertainties, you should not place undue reliance on these forward-looking statements as actual events or results may differ materially from those projected in the forward-looking statements due to various factors, including, but not limited to, those set forth under the heading “Risk Factors” in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference, and any free writing prospectus that we have authorized for use. These forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements contained in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference, and any free writing prospectus that we have authorized for use by these cautionary statements. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. Before deciding to purchase our common stock, you should carefully consider the risk factors discussed herein or incorporated by reference, in addition to the other information set forth in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference, and any free writing prospectus that we have authorized for use, with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

S-8


Use of proceeds
We will not receive any of the proceeds from the sale of common stock offered by the selling stockholders.

S-9


Dividend policy
We have never declared or paid any dividends on our common stock. In addition, our loan and security agreement with Silicon Valley Bank contains restrictive covenants that prohibit us, subject to certain exceptions, from paying dividends on our common stock, and future debt securities or other financing arrangements could contain similar or more restrictive negative covenants. We currently intend to retain all available funds and any future earnings for the operation and expansion of our business. We do not anticipate declaring or paying cash dividends in the foreseeable future. The payment of any future dividends will be at the discretion of our board of directors and will depend on our results of operations, capital requirements, financial condition, prospects, contractual arrangements, any limitations on payment of dividends present in our current and future debt agreements, and other factors that our board of directors may deem relevant.

S-10


Selling stockholders
The selling stockholders are holders of our common stock originally acquired in connection with our initial public offering, or IPO, upon conversion of preferred stock purchased by such stockholders in private financings that we conducted prior to our IPO. Our director, Richard M. Wells, is a Managing Director at Insight Venture Management, LLC, an entity affiliated with the Insight Partners.
We are party to an investors’ rights agreement with the selling stockholders named in this prospectus supplement, which provides the selling stockholders and the other holders of our common stock party thereto with certain rights with respect to the registration of shares of common stock held by them under the Securities Act. Additional information regarding such registration rights is contained in the accompanying prospectus under the heading “Description of Capital Stock–Registration Rights.”
Except for the ownership of the shares of common stock that may be offered and sold by the selling stockholders, the participation in the transactions described above, the investors’ rights agreement and the position that Mr. Wells holds on our board of directors, the selling stockholders have not had any material relationship with us or our affiliates within the past three years.
The table below, including the footnotes, sets forth the selling stockholders and other information regarding the beneficial ownership of the shares of common stock held by each of the selling stockholders based on information provided to us by the selling stockholders. Generally, a person “beneficially owns” shares of our common stock if the person has or shares with others the right to vote those shares or to dispose of them, or if the person has the right to acquire voting or disposition rights within 60 days. The percent of shares beneficially owned prior to and after the offering is based on 101,263,716 shares of our common stock issued and outstanding as of July 24, 2020.
Name of selling stockholder
 
Shares beneficially
owned prior to
offering
 
Number of
shares to be sold

 
Shares beneficially
owned after
offering
(1)
 
Shares

 
Percentage
 
 
Shares

 
Percentage
Entities affiliated with Insight Partners(2)
 
22,333,780

 
22.1%
 
8,000,000

 
14,333,780

 
14.2%
 
 
 
 
 
 
 
 
 
 
 
(1)
Assumes no exercise of the underwriters’ option to purchase additional shares. See “Underwriting.”
(2)
Consists of (a) 6,873,043 shares of common stock held by Insight Venture Partners IX, L.P., or IVP IX, (b) 3,415,047 shares of common stock held by Insight Venture Partners (Cayman) IX, L.P., or IVP (Cayman) IX, (c) 728,197 shares of common stock held by Insight Venture Partners (Delaware) IX, L.P., or IVP (Delaware) IX, (d) 137,191 shares of common stock held by Insight Venture Partners IX (Co-Investors), L.P., or IVP IX (Co-Investors), and, collectively with IVP IX, IVP (Cayman) IX and IVP (Delaware) IX, the “IVP IX Funds”, (e) 25,699 shares of common stock held by IVP (Venice), L.P., or IVP Venice, (f) 3,230,422 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund, L.P., or IVP Coinvestment, (g) 2,597,069 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (Cayman), L.P., or IVP Coinvestment (Cayman), (h) 2,388,016 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (Delaware), L.P., or IVP Coinvestment (Delaware), and (i) 2,939,096 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (B), L.P., or IVP Coinvestment (B), and, collectively with IVP Coinvestment, IVP Coinvestment (Cayman) and IVP Coinvestment (Delaware), the “IVP Coinvestment Funds” and, together with the IVP IX Funds and IVP Venice, the “IVP Funds.” Insight Venture Associates IX, Ltd., or IVA IX Ltd., is the general partner of Insight Venture Associates IX, L.P., which is the general partner of each of the IVP IX Funds. Insight Venture Associates Growth-Buyout Coinvestment, Ltd., or IVA Coinvestment Ltd., is the general partner of Insight Venture Associates Growth-Buyout Coinvestment, L.P., which is the general partner of each of the IVP Coinvestment Funds. Insight Holdings Group, LLC, or Insight Holdings, is the sole shareholder of each of IVA IX Ltd., and IVA Coinvestment Ltd, Insight Holdings is the sole shareholder of Insight Venture Associates X, Ltd., which is the general partner of IVP GP (Venice), which in turn is the manager of IVP Venice. Each of Jeffrey L. Horing, Deven Parekh, Peter Sobiloff, Jeffrey Lieberman and Michael Triplett is a member of the board of managers of Insight Holdings and as such may be deemed to have shared voting and dispositive power over the shares held by each of the IVP Funds. Richard M. Wells is a Managing Director at Insight Venture Management, LLC, an entity affiliated with the IVP Funds, but does not have voting and dispositive power over the shares held by IVP Funds. The principal business address for all entities and individuals affiliated with Insight Partners is c/o Insight Partners, 1114 Avenue of the Americas, 36th Floor, New York, New York, 10036.

S-11


Certain material U.S. federal income tax consequences for non-U.S. holders
The following is a discussion of certain material U.S. federal income tax considerations applicable to non-U.S. holders (as defined below) with respect to their ownership and disposition of shares of our common stock issued pursuant to this offering, but does not purport to be a complete analysis of all potential tax effects. All prospective non-U.S. holders of our common stock should consult their own tax advisors with respect to the U.S. federal income tax consequences of the purchase, ownership and disposition of our common stock, as well as any consequences arising under the laws of any other taxing jurisdiction, including any state, local and non-U.S. tax consequences and any U.S. federal non-income tax consequences. In general, a non-U.S. holder means a beneficial owner of our common stock (other than a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is not, for U.S. federal income tax purposes:
an individual who is a citizen or resident of the United States;
a corporation, or an entity treated as a corporation for U.S. federal income tax purposes, created or organized in the United States or under the laws of the United States or of any state thereof or the District of Columbia;
an estate, the income of which is subject to U.S. federal income tax regardless of its source; or
a trust if (1) a U.S. court can exercise primary supervision over the trust’s administration and one or more U.S. persons have the authority to control all of the trust’s substantial decisions or (2) the trust has a valid election in effect under applicable U.S. Treasury Regulations to be treated as a U.S. person.
This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, which we refer to as the Code, existing U.S. Treasury Regulations promulgated thereunder, published administrative rulings and judicial decisions, all as in effect as of the date of this prospectus supplement. These laws are subject to change and to differing interpretation, possibly with retroactive effect. Any change or differing interpretation could alter the tax consequences to non-U.S. holders described in this prospectus supplement.
This discussion is limited to non-U.S. holders that hold shares of our common stock as a capital asset within the meaning of Section 1221 of the Code (generally, for investment). This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular non-U.S. holder in light of that non-U.S. holder’s individual circumstances, nor does it address any aspects of U.S. estate or gift tax, or any state, local or non-U.S. taxes. This discussion also does not consider any specific facts or circumstances that may apply to a non-U.S. holder and does not address all special tax rules applicable to particular non-U.S. holders, such as holders that own, or are deemed to own, more than 5% of our capital stock (except to the extent specifically set forth below), corporations that accumulate earnings to avoid U.S. federal income tax, tax-exempt organizations, banks, financial institutions, insurance companies, brokers, dealers or traders in securities, commodities or currencies, tax-qualified retirement plans, holders subject to the alternative minimum tax or Medicare contribution tax, holders who hold or receive our common stock pursuant to the exercise of employee stock options or otherwise as compensation, holders holding our common stock as part of a hedge, straddle or other risk reduction strategy, conversion transaction or other integrated investment, holders deemed to sell our common stock under the constructive sale provisions of the Code, persons subject to special tax accounting rules under Section 451(b) of the Code, “qualified foreign pension funds” as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds, controlled foreign corporations, passive foreign investment companies and certain former citizens or long-term residents of the United States.

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In addition, this discussion does not address the tax treatment of partnerships (or entities or arrangements that are treated as partnerships for U.S. federal income tax purposes) or persons that hold their common stock through such partnerships or such entities or arrangements. If a partnership, including any entity or arrangement treated as a partnership for U.S. federal income tax purposes, holds shares of our common stock, the U.S. federal income tax treatment of a partner in such partnership will generally depend upon the status of the partner, the activities of the partnership and certain determinations made at the partner level. Such partners and partnerships should consult their tax advisors regarding the tax consequences of the purchase, ownership and disposition of our common stock.
There can be no assurance that the Internal Revenue Service, which we refer to as the IRS, will not challenge one or more of the tax consequences described herein, and we have not obtained, nor do we intend to obtain, a ruling with respect to the U.S. federal income tax consequences with respect to the matters discussed below.
Distributions on our common stock
As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying distributions to holders of our common stock in the foreseeable future. However, distributions, if any, on our common stock generally will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder’s investment, up to such holder’s adjusted tax basis in the common stock. Any remaining excess will be treated as capital gain from the sale or exchange of such common stock, subject to the tax treatment described below in “Gain on Sale, Exchange or Other Disposition of Our Common Stock.”
Subject to the discussions below regarding effectively connected income, dividends paid to a non-U.S. holder will generally be subject to withholding of U.S. federal income tax at a 30% rate, or such lower rate as may be specified by an applicable income tax treaty. A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty generally will be required to provide a properly executed IRS Form W-8BEN or W-8BEN-E (or other appropriate form), certifying the non-U.S. holder’s entitlement to benefits under that treaty. This certification must be provided to us or our paying agent prior to the payment of dividends and must be updated periodically. In the case of a non-U.S. Holder that is an entity, Treasury Regulations and the relevant tax treaty provide rules to determine whether, for purposes of determining the applicability of a tax treaty, dividends will be treated as paid to the entity or to those holding an interest in that entity. If a non-U.S. holder holds stock through a financial institution or other agent acting on the holder’s behalf, the non-U.S. holder will be required to provide appropriate documentation to such agent. The non-U.S. holder’s agent will then be required to provide certification to us or our paying agent, either directly or through intermediaries. If you are eligible for a reduced rate of U.S. federal withholding tax under an income tax treaty and you do not timely file the required certification, you may be able to obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty.
Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification requirements. To claim the exemption, the non-U.S. holder must furnish to us or the applicable withholding agent a valid IRS Form W-8ECI (or applicable successor form), certifying that the dividends are effectively connected with the non-U.S. holder’s conduct of a trade or business within the United States. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same U.S. federal income tax rates applicable to U.S. persons (as defined in the Code), unless a specific treaty exemption applies. Any U.S. effectively connected income received by a non-U.S.

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holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty.
Gain on sale, exchange or other disposition of our common stock
Subject to the discussions below regarding backup withholding and foreign accounts, in general, a non-U.S. holder will not be subject to any U.S. federal income tax on any gain realized upon such holder’s sale, exchange or other disposition of shares of our common stock unless:
the gain is effectively connected with a U.S. trade or business of the non-U.S. holder and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed base maintained in the United States by such non-U.S. holder, in which case the non-U.S. holder generally will be taxed at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code) and, if the non-U.S. holder is a foreign corporation, the branch profits tax described above in “Distributions on Our Common Stock” may also apply;
the non-U.S. holder is a nonresident alien individual who is present in the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the non-U.S. holder will be subject to a 30% tax (or such lower rate as may be specified by an applicable income tax treaty) on the net gain derived from the disposition, which may be offset by certain U.S. source capital losses of the non-U.S. holder, if any (even though the individual is not considered a resident of the United States), provided the non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses; or
our common stock constitutes a U.S. real property interest because we are, or have been, at any time during the five-year period preceding such disposition (or the non-U.S. holder’s holding period, if shorter) a “U.S. real property holding corporation.” Even if we are or become a U.S. real property holding corporation, provided that our common stock is regularly traded on an established securities market, our common stock will be treated as a U.S. real property interest only with respect to a non-U.S. holder that holds more than 5% of our outstanding common stock, directly or indirectly, actually or constructively, during the shorter of the five-year period ending on the date of the disposition or the period that the non-U.S. holder held our common stock. In such case, such non-U.S. holder generally will be taxed on its net gain derived from the disposition at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code). Generally, a corporation is a U.S. real property holding corporation only if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one in the future. No assurance can be provided that our common stock will be regularly traded on an established securities market for purposes of the rules described above.
Backup withholding and information reporting
We must report annually to the IRS and to each non-U.S. holder the gross amount of distributions on our common stock paid to such holder, regardless of whether such distributions constitute dividends or whether any tax was actually withheld. Non-U.S. holders will have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate (currently 24%) with respect to dividends on our common stock. U.S. backup withholding generally will not apply to a non-U.S. holder who provides a properly executed IRS Form W-8BEN or W-8BEN-E or otherwise establishes an exemption.
Information reporting and backup withholding will generally apply to the proceeds of a disposition of our common stock by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside

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the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker.
Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them.
Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement.
Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder may be allowed as a credit against the non-U.S. holder’s U.S. federal income tax liability, if any, and may entitle such holder to a refund, provided that the required information is timely furnished to the IRS.
Foreign accounts
Sections 1471 through 1474 of the Code (commonly referred to as FATCA) generally impose a U.S. federal withholding tax of 30% on certain payments made to a “foreign financial institution” (as specifically defined for this purpose), unless such institution enters into an agreement with the U.S. government to, among other things, withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding U.S. account holders of such institution (which may include certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners). Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing these withholding and reporting requirements may be subject to different rules. FATCA also generally imposes a 30% withholding tax on certain payments made to a non-financial foreign entity, unless such entity provides the withholding agent with either a certification that it does not have any substantial direct or indirect U.S. owners or information regarding substantial direct and indirect U.S. owners of the entity. The withholding tax under FATCA described above will not apply if the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from the rules. The FATCA withholding provisions described above currently apply to dividends on our common stock. The FATCA withholding provisions also would apply to the gross proceeds of a disposition of our common stock, except that the U.S. Treasury Department has released proposed regulations which, if finalized in their present form, would eliminate such withholding. In its preamble to such proposed regulations, the U.S. Treasury Department stated that taxpayers generally may rely on the proposed regulations until final regulations are issued.
Under certain circumstances, a non-U.S. holder might be eligible for refunds or credits of such taxes. Non-U.S. holders are encouraged to consult with their tax advisors regarding the possible implications of FATCA on their investment in our common stock.
EACH PROSPECTIVE INVESTOR SHOULD CONSULT ITS OWN TAX ADVISOR REGARDING THE TAX CONSEQUENCES OF PURCHASING, HOLDING AND DISPOSING OF OUR COMMON STOCK, AS WELL AS TAX CONSEQUENCES ARISING UNDER ANY STATE, LOCAL, NON-U.S. OR U.S. FEDERAL NON-INCOME TAX LAWS.

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Underwriting
The selling stockholders are offering the shares of common stock described in this prospectus supplement through a number of underwriters. J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC are acting as representatives of the underwriters. We and the selling stockholders have entered into an underwriting agreement with the underwriters. Subject to the terms and conditions of the underwriting agreement, the selling stockholders have agreed to sell to the underwriters, and each underwriter has severally agreed to purchase, at the public offering price less the underwriting discounts and commissions set forth on the cover page of this prospectus supplement, the number of shares of common stock listed next to its name in the following table:
Name
 
Number of shares
J.P. Morgan Securities LLC
 
 
Morgan Stanley & Co. LLC
 
 
Barclays Capital Inc.
 
 
Total
 
 
 
 
 
The underwriters are committed to purchase all the shares of common stock offered by the selling stockholders if they purchase any shares. The underwriting agreement also provides that if an underwriter defaults, the purchase commitments of non-defaulting underwriters may also be increased or the offering may be terminated.
The underwriters propose to offer shares of common stock directly to the public at the public offering price set forth on the cover page of this prospectus supplement and to certain dealers at that price less a concession not in excess of $           per share. Any such dealers may resell shares to certain other brokers or dealers at a discount of up to $           per share from the public offering price. After the initial offering of the shares to the public, if all of the shares of common stock are not sold at the public offering price, the underwriters may change the offering price and the other selling terms. Sales of any shares made outside of the United States may be made by affiliates of the underwriters.
The underwriters have an option to buy up to            additional shares of common stock from the selling stockholders. The underwriters have 30 days from the date of this prospectus supplement to exercise this option to purchase additional shares. If any shares are purchased with this option to purchase additional shares, the underwriters will purchase shares in approximately the same proportion as shown in the table above. If any additional shares of common stock are purchased, the underwriters will offer the additional shares on the same terms as those on which the shares are being offered.
The underwriting fee is equal to the public offering price per share of common stock less the amount paid by the underwriters to the selling stockholders per share of common stock. The underwriting fee is $         per share. The following table shows the per share and total underwriting discounts and commissions to be paid to the underwriters by the selling stockholders assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares.
Paid by the selling stockholders
 
No exercise
 
Full exercise
Per share
$
 
$
Total
$
 
$
 
 
 
 

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We estimate that our out-of-pocket expenses for this offering will be approximately $         . We have agreed to reimburse the underwriters for certain of their expenses relating to the review by FINRA of the terms of sale of the shares of common stock as set forth in the underwriting agreement, which are not expected to exceed $20,000.
A prospectus supplement in electronic format may be made available on the web sites maintained by one or more underwriters, or selling group members, if any, participating in the offering. The underwriters may agree to allocate a number of shares to underwriters and selling group members for sale to their online brokerage account holders. Internet distributions will be allocated by the representatives to underwriters and selling group members that may make Internet distributions on the same basis as other allocations.
Our directors, our executive officers and the selling stockholders have agreed that, without the prior written consent of J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC on behalf of the underwriters, they will not, during the period ending 60 days after the date of this prospectus supplement, or the “restricted period”:
offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend or otherwise transfer or dispose of, directly or indirectly, any shares of common stock or any securities convertible into or exercisable or exchangeable for shares of common stock;
file any registration statement with the SEC relating to the offering of any shares of common stock or any securities convertible into or exercisable or exchangeable for common stock; or
enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the common stock,
whether any such transaction described above is to be settled by delivery of common stock or such other securities, in cash or otherwise. In addition, we and each such person agrees that, without the prior written consent of J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC on behalf of the underwriters, we or such other person will not, during the restricted period, make any demand for, or exercise any right with respect to, the registration of any shares of common stock or any security convertible into or exercisable or exchangeable for common stock.
The restrictions on our actions, as described above, do not apply to certain transactions, including:
the sale of shares to the underwriters;
transactions by any person other than us relating to shares of common stock or other securities acquired in open market transactions of the shares; provided that no filing under Section 16(a) of the Exchange Act is required or voluntarily made in connection with subsequent sales of the common stock or other securities acquired in such open market transactions;
transfers of shares of common stock or any security convertible into or exercisable or exchangeable for common stock (i) as a bona fide gift, (ii) to an immediate family member (as defined below) or to any trust for the direct or indirect benefit of the holder or an immediate family member of the holder, (iii) to any corporation, partnership, limited liability company, investment fund or other entity controlled or managed, or under common control or management by, the holder or (iv) by will, other testamentary document or intestate succession to the legal representative, heir, beneficiary or an immediate family member of the holder, provided that, (a) each transferee shall sign and deliver a lock-up agreement and (b) no filing under Section 16(a) of the Exchange Act reporting a reduction in beneficial ownership of shares of common stock shall be required or shall be voluntarily made other than any required Form 5 filing during the restricted period;
dispositions, transfers or distributions to (i) another corporation, partnership, limited liability company, trust or other business entity that is an affiliate, or to any investment fund or other entity controlled or managed by the holder or its affiliates, or (ii) as part of a distribution, transfer or disposition without

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consideration by the holder to its stockholders, current or former partners (general or limited), members, beneficiaries or other equity holders, or to the estates of any such stockholders, partners, beneficiaries or other equity holders; provided that (a) each transferee, recipient or distributee shall sign and deliver a lock-up letter and (b) no filing under Section 16(a) of the Exchange Act, reporting a reduction in beneficial ownership of shares of common stock, shall be required or shall be voluntarily made other than any required Form 5 filing during the restricted period;
the issuance or receipt of shares of common stock upon the exercise of options or vesting of restricted stock unit awards, insofar as such options or restricted stock unit awards are outstanding as of the date of the final prospectus supplement for this offering and granted under any award, equity incentive plan or stock purchase plan described herein, provided that the shares received upon exercise of such option or vesting of such restricted stock unit award shall remain subject to the lock up, or (ii) the transfer of shares or any securities convertible thereto upon a vesting event of securities or upon the exercise of options to purchase securities on a “cashless” or “net exercise” basis to the extent permitted by the instruments representing such options or restricted stock awards insofar as such options or restricted stock unit awards are outstanding as of the date of the final prospectus supplement for this offering and granted under any award, equity incentive plan or stock purchase plan described in herein and so long as such “cashless” exercise or “net exercise” is effected solely by the surrender of outstanding options or other securities to us and our cancellation of all or a portion thereof to pay the exercise price (including the payment of taxes due as a result of such vesting event or exercise), withholding tax obligations and/or “sell to cover” or similar transactions in connection with the settlement of restricted stock unit awards, but for the avoidance of doubt, excluding all methods of exercise that would involve a sale of any shares relating to options, whether to cover the applicable exercise price, withholding tax obligations or otherwise, provided that in the case of either (i) or (ii), any filing under Section 16(a) of the Exchange Act shall clearly indicate in the footnotes thereto that (A) the filing relates to the circumstances described in (i) or (ii), as the case may be, (B) no shares were sold by the reporting person (except with respect to a “sell to cover” or similar transaction, in such case only such shares as required to cover such transaction were sold by the reporting person) and (C) in the case of (i), the shares received upon exercise of the option are subject to a lock-up letter;
the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act, provided that (i) such plan does not provide for the transfer during the period subject to the lock up and (ii) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made regarding the establishment of such plan, such announcement or filing shall include a statement to such effect;
the transfer of shares pursuant to a qualified domestic order or in connection with a divorce settlement, provided that (i) each such transferee shall sign and deliver a lock-up letter and (ii) any filing required under Section 16(a) of the Exchange Act shall clearly indicate in the footnotes thereto that the filing relates to the circumstances described above and (iii) the holder does not otherwise voluntarily effect any other public filing or announcement regarding such transfers;
the transfer of shares of pursuant to a bona fide third-party tender offer, merger, consolidation or other similar transaction that is approved by our board of directors, made to all of our stockholders involving a change of control;
the transfer of shares of pursuant to a trading plan pursuant to Rule 10b5-1 under the Exchange Act that entered into prior to the date of this letter agreement; provided, that to the extent a public announcement or filing under the Exchange Act, if any, is required or voluntarily made regarding any such transfer, such announcement or filing shall include a statement to the effect that the transfer was made pursuant to a trading plan pursuant to Rule 10b5-1;
in the case of one of our affiliates, the transfer of up to 250,000 shares made during the first 30 days of the restricted period and the transfer of up to an additional 250,000 shares made during the latter 30 days of the restricted period provided, that to the extent a public announcement or filing under the

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Exchange Act, if any, is required or voluntarily made regarding any such transfer, such announcement or filing shall include a statement to the effect that the transfer was made pursuant to an exception to the lock up; and
a sale or issuance of or entry into an agreement to sell or issue common stock or any securities convertible into or exercisable or exchangeable for common stock by us in connection with one or more mergers; acquisitions of securities, businesses, property or other assets, products or technologies; joint ventures; commercial relationships or other strategic corporate transactions or alliances; provided that the aggregate amounts of common stock or any securities convertible into or exercisable or exchangeable for common stock (on an as-converted, as-exercised or as-exchanged basis) that we may sell or issue or agree to sell or issue pursuant to this exception shall not exceed 5% of the total number of shares of our common stock issued and outstanding immediately following the completion of this offering and provided further that each recipient shall execute a lock-up agreement substantially in the form described here.
J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC, in their sole discretion, may release the securities subject to any of the lock-up agreements with the underwriters described above, in whole or in part at any time.
Record holders of our securities are typically the parties to the lock-up agreements with the underwriters and the market standoff agreements with us referred to above, while holders of beneficial interests in our shares who are not also record holders in respect of such shares are not typically subject to any such agreements or other similar restrictions. Accordingly, we believe that certain holders of beneficial interests who are not record holders and are not bound by market standoff or lock-up agreements could enter into transactions with respect to those beneficial interests that negatively impact our stock price. In addition, a stockholder who is neither subject to a market standoff agreement with us nor a lock-up agreement with the underwriters may be able to sell, short sell, transfer, hedge, pledge, lend or otherwise dispose of or attempt to sell short sell, transfer, hedge, pledge, lend or otherwise dispose of, their equity interests at any time after the closing of this offering.
We and the selling stockholders have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act.
Our common stock is listed on The Nasdaq Global Select Market under the symbol “TENB.”
In connection with this offering, the underwriters may engage in stabilizing transactions, which involves making bids for, purchasing and selling shares of common stock in the open market for the purpose of preventing or retarding a decline in the market price of the common stock while this offering is in progress. These stabilizing transactions may include making short sales of common stock, which involves the sale by the underwriters of a greater number of shares of common stock than they are required to purchase in this offering, and purchasing shares of common stock on the open market to cover positions created by short sales. Short sales may be “covered” shorts, which are short positions in an amount not greater than the underwriters’ option to purchase additional shares referred to above, or may be “naked” shorts, which are short positions in excess of that amount. The underwriters may close out any covered short position either by exercising their option to purchase additional shares, in whole or in part, or by purchasing shares in the open market. In making this determination, the underwriters will consider, among other things, the price of shares available for purchase in the open market compared to the price at which the underwriters may purchase shares through the option to purchase additional shares. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the open market that could adversely affect investors who purchase in this offering. To the extent that the underwriters create a naked short position, they will purchase shares in the open market to cover the position.
The underwriters have advised us that, pursuant to Regulation M of the Securities Act, they may also engage in other activities that stabilize, maintain or otherwise affect the price of the common stock, including the imposition of penalty bids. This means that if the representatives of the underwriters

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purchase common stock in the open market in stabilizing transactions or to cover short sales, the representatives can require the underwriters that sold those shares as part of this offering to repay the underwriting discount received by them.
These activities may have the effect of raising or maintaining the market price of the common stock or preventing or retarding a decline in the market price of the common stock, and, as a result, the price of the common stock may be higher than the price that otherwise might exist in the open market. If the underwriters commence these activities, they may discontinue them at any time. The underwriters may carry out these transactions on the The Nasdaq Global Select Market, in the over‑the‑counter market or otherwise.
In addition, in connection with this offering certain of the underwriters (and selling group members) may engage in passive market making transactions in our common stock on The Nasdaq Global Select Market prior to the pricing and completion of this offering. Passive market making consists of displaying bids on The Nasdaq Global Select Market no higher than the bid prices of independent market makers and making purchases at prices no higher than these independent bids and effected in response to order flow. Net purchases by a passive market maker on each day are generally limited to a specified percentage of the passive market maker’s average daily trading volume in the common stock during a specified period and must be discontinued when such limit is reached. Passive market making may cause the price of our common stock to be higher than the price that otherwise would exist in the open market in the absence of these transactions. If passive market making is commenced, it may be discontinued at any time.
Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.
Certain of the underwriters and their affiliates have provided in the past to us and our affiliates and may provide from time to time in the future certain commercial banking, financial advisory, investment banking and other services for us and such affiliates in the ordinary course of their business, for which they have received and may continue to receive customary fees and commissions. In addition, from time to time, certain of the underwriters and their affiliates may effect transactions for their own account or the account of customers, and hold on behalf of themselves or their customers, long or short positions in our debt or equity securities or loans, and may do so in the future.
Selling restrictions
Canada
The shares may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the shares must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.
Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser

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within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.
Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.
European Economic Area and the UK
In relation to each Member State of the European Economic Area and the United Kingdom (each a “Relevant State”), no shares have been offered or will be offered pursuant to this offering to the public in that Relevant State prior to the publication of a prospectus in relation to the shares which has been approved by the competent authority in that Relevant State or, where appropriate, approved in another Relevant State and notified to the competent authority in that Relevant State, all in accordance with the Prospectus Regulation, except that offers of shares may be made to the public in that Relevant State at any time under the following exemptions under the Prospectus Regulation:
(a)
to any legal entity which is a qualified investor as defined under the Prospectus Regulation;
(b)
to fewer than 150 natural or legal persons (other than qualified investors as defined under the Prospectus Regulation), subject to obtaining the prior consent of the underwriters; or
(c)
in any other circumstances falling within Article 1(4) of the Prospectus Regulation,
provided that no such offer of shares shall require us or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation and each person who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with each of the underwriters and the Company that it is a “qualified investor” within the meaning of Article 2(e) of the Prospectus Regulation. In the case of any shares being offered to a financial intermediary as that term is used in the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed that the shares acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer of any shares to the public other than their offer or resale in a Relevant State to qualified investors as so defined or in circumstances in which the prior consent of the underwriters have been obtained to each such proposed offer or resale.
For the purposes of this provision, the expression an “offer to the public” in relation to shares in any Relevant State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression “Prospectus Regulation” means Regulation (EU) 2017/1129.
United Kingdom
In addition, in the United Kingdom, this document is being distributed only to, and is directed only at, and any offer subsequently made may only be directed at persons who are “qualified investors” (as defined in the Prospectus Regulation) (i) who have professional experience in matters relating to investments falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”) and/or (ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”) or otherwise in circumstances which have not resulted and will not result in an offer to the public of the shares in the United Kingdom within the meaning of the Financial Services and Markets Act 2000.
(a)
Any person in the United Kingdom that is not a relevant person should not act or rely on the information included in this document or use it as basis for taking any action. In the United Kingdom,

S-21


any investment or investment activity that this document relates to may be made or taken exclusively by relevant persons.
Hong Kong
The shares have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571 of the Laws of Hong Kong) (the “SFO”) of Hong Kong and any rules made thereunder; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies (Winding Up and Miscellaneous Provisions) Ordinance (Cap. 32) of Hong Kong) (the “CO”) or which do not constitute an offer to the public within the meaning of the CO. No advertisement, invitation or document relating to the shares has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the SFO and any rules made thereunder.
Japan
The shares have not been and will not be registered pursuant to Article 4, Paragraph 1 of the Financial Instruments and Exchange Act. Accordingly, none of the shares nor any interest therein may be offered or sold, directly or indirectly, in Japan or to, or for the benefit of, any “resident” of Japan (which term as used herein means any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan or to or for the benefit of a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the Financial Instruments and Exchange Act and any other applicable laws, regulations and ministerial guidelines of Japan in effect at the relevant time.
Singapore
Each underwriter has acknowledged that this prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, each underwriter has represented and agreed that it has not offered or sold any shares or caused the shares to be made the subject of an invitation for subscription or purchase and will not offer or sell any shares or cause the shares to be made the subject of an invitation for subscription or purchase, and has not circulated or distributed, nor will it circulate or distribute, this prospectus supplement or any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the shares, whether directly or indirectly, to any person in Singapore other than:
(a)
to an institutional investor (as defined in Section 4A of the Securities and Futures Act (Chapter 289) of Singapore, as modified or amended from time to time (the “SFA”)) pursuant to Section 274 of the SFA;
(b)
to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA and in accordance with the conditions specified in Section 275 of the SFA; or
(c)
otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.
Where the shares are subscribed or purchased under Section 275 of the SFA by a relevant person which is:
(a)
a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or

S-22


(b)
a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor,
securities or securities-based derivatives contracts (each term as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares pursuant to an offer made under Section 275 of the SFA except:
(i)
to an institutional investor or to a relevant person, or to any person arising from an offer referred to in Section 276(4)(i)(B) of the SFA;
(ii)
where no consideration is or will be given for the transfer;
(iii)
where the transfer is by operation of law;
(iv)
as specified in Section 276(7) of the SFA; or
as specified in Regulation 37A of the Securities and Futures (Offers of Investments) (Securities and Securities-based Derivatives Contracts) Regulations 2018.

S-23


Legal matters
The validity of the shares of common stock being offered by this prospectus supplement and the accompanying prospectus will be passed upon for us by Cooley LLP, Reston, Virginia. Wilson Sonsini Goodrich & Rosati, Professional Corporation, Washington, District of Columbia, is representing the underwriters in connection with this offering. Willkie Farr & Gallagher LLP, New York, New York, is representing the selling stockholders in connection with this offering.
Experts
Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2019, and the effectiveness of our internal control over financial reporting as of December 31, 2019, (excluding the internal control over financial reporting of Indegy, Inc.) as set forth in their reports, which are incorporated by reference in this prospectus supplement and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst &Young LLP’s reports, given on their authority as experts in accounting and auditing.
Where you can find more information
This prospectus supplement is part of a registration statement we filed with the SEC. This prospectus supplement does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus supplement, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on the information contained in this prospectus supplement or incorporated by reference. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume the information in this prospectus supplement is accurate as of any date other than the date on the front page of this prospectus supplement, regardless of the time of delivery of this prospectus supplement or any sale of the securities offered by this prospectus supplement.
We file annual, quarterly, and current reports, proxy statements, and other information with the SEC. You may read and copy the registration statement, as well as any other document filed by us with the SEC, at the SEC’s website at www.sec.gov.
We maintain a website at www.tenable.com. Information contained in or accessible through our website does not constitute a part of this prospectus supplement.

S-24


Incorporation of certain information by reference
The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying prospectus. Information in this prospectus supplement and the accompanying prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus supplement and the accompanying prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus supplement and the accompanying prospectus. We incorporate by reference into this prospectus supplement and the accompanying prospectus and the registration statement of which this prospectus supplement and the accompanying prospectus is a part the information or documents listed below that we have filed with the SEC (Commission File No. 001-38600):
our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 28, 2020;
our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, filed with the SEC on May 7, 2020;
our Current Reports on Form 8-K filed with the SEC on June 3, 2020 and July 28, 2020 (Item 1.01) (as to information therein explicitly filed with the SEC only);
the information specifically incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2019 from our Definitive Proxy Statement on Schedule 14A filed with the SEC on April 15, 2020; and
the description of our common stock in our registration statement on Form 8-A filed with the SEC on July 20, 2018, including any amendments thereto or reports filed for the purposes of updating this description.
Any information in any of the foregoing documents will automatically be deemed to be modified or superseded to the extent that information in this prospectus supplement or in a later filed document that is incorporated or deemed to be incorporated herein by reference modifies or replaces such information.
We also incorporate by reference any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, until we file a post-effective amendment which indicates the termination of the offering of the securities made by this prospectus supplement and the accompanying prospectus. Information in such future filings updates and supplements the information provided in this prospectus supplement and the accompanying prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.
You can request a copy of these filings, at no cost, by writing or telephoning us at the following address or telephone number:
Tenable Holdings, Inc.
7021 Columbia Gateway Drive, Suite 500
Columbia, Maryland 21046
(410) 872-0555
Attention: Corporate Secretary

S-25


PROSPECTUS
22,333,780 Shares
https://cdn.kscope.io/9a241d7f4b299fba7b9afc7b82a057c8-tenablelogo1a.jpg
Tenable Holdings, Inc.
Common Stock
The selling stockholders identified in this prospectus may offer and sell, from time to time, up to an aggregate of 22,333,780 shares of common stock on the terms described in this prospectus or in an applicable prospectus supplement.
This prospectus describes the general manner in which the shares of common stock may be offered and sold by the selling stockholders. If necessary, the specific manner in which these securities may be offered and sold will be described in a prospectus supplement. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before you buy the common stock being offered.
Our common stock is listed on The Nasdaq Global Select Market under the symbol “TENB.” On July 28, 2020, the last reported sale price of our common stock was $30.37 per share.
The common stock may be sold directly to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis at a fixed price or prices, at market prices prevailing at the time or at negotiated prices. For additional information on the methods of sale, you should refer to information under the heading “Plan of Distribution” in this prospectus. If any agents or underwriters are involved in the sale of common stock with respect to which this prospectus is being delivered, the names of such agents or underwriters and any applicable fees, commissions, discounts or options to purchase additional shares will be set forth in a prospectus supplement. Unless the applicable prospectus supplement provides otherwise, we will not receive any proceeds from the sale of common stock by selling stockholders.
Investing in our common stock involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus that we have authorized for use in connection with a specific offering, and under similar headings in the other documents that are incorporated by reference into this prospectus.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
The date of this prospectus is July 29, 2020.



TABLE OF CONTENTS

i


ABOUT THIS PROSPECTUS
This prospectus is a part of an automatic registration statement on Form S-3 that we filed with the U.S. Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act. Under this shelf registration process, the selling stockholders may offer and sell common stock from time to time in one or more offerings.
This prospectus may be supplemented from time to time by one or more prospectus supplements. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in any documents that we have incorporated by reference into this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or free writing prospectus, you should rely on the prospectus supplement or free writing prospectus, as applicable. You should read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the heading “Incorporation of Certain Information by Reference,” before buying any of the common stock being offered.
Neither we or any selling stockholder, nor any agent, underwriter or dealer has authorized any person to give any information or to make any representation other than those contained or incorporated by reference into this prospectus, any applicable prospectus supplement or any related free writing prospectus prepared by or on behalf of us or to which we have referred you. This prospectus, any applicable supplement to this prospectus or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.
You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date.
This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described under the heading “Where You Can Find More Information.”

ii


SUMMARY
This summary highlights selected information from this prospectus and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our common stock discussed under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements, and the exhibits to the registration statement of which this prospectus is a part.
Unless the context requires otherwise, references in this prospectus to the “Company,” “Tenable Holdings,” “we,” “us” and “our” refer to Tenable Holdings, Inc. and its subsidiaries on a consolidated basis. “Tenable”, the Tenable logo, and our other trademarks or service marks appearing in this prospectus are the property of Tenable Holdings, Inc. This prospectus contains additional trade names, trademarks and service marks of others, which are the property of their respective owners. Solely for convenience, trademarks and trade names referred to in this prospectus may appear without the ® or ™ symbols.
Company Overview
We are a leading provider of solutions for a new category of cybersecurity that we call Cyber Exposure. Cyber Exposure is a discipline for managing, measuring and comparing cybersecurity risk in the digital era. Our enterprise platform enables broad visibility into an organization’s cyber exposure across the modern attack surface and deep insights that help organizations translate vulnerability data into business insights to understand and reduce their cybersecurity risk.
Our enterprise platform offerings include Tenable.io, which is our software as a service, or SaaS, offering and Tenable.sc, which is our on-premises offering, both of which provide organizations with applications purpose-built for areas of both traditional and modern attack surfaces, including IT infrastructure and applications, cloud environments and industrial Internet of things, or IoT, and operational technology, or OT, environments. These applications are designed with views, workflows and dashboards to help identify vulnerabilities, internal and regulatory compliance violations, misconfigurations and other cybersecurity issues, prioritize these issues for remediation, and provide insightful remediation guidance.
Our enterprise platform offerings are primarily sold on a subscription basis with a one-year term. Our subscription terms are generally not longer than three years. These offerings are typically prepaid in advance. To a lesser extent, we generate ratably recognizable revenue from perpetual licenses and from the related ongoing maintenance.
We sell and market our products and services through our field sales force that works closely with our channel partners, which includes a network of distributors and resellers, in developing sales opportunities. We use a two-tiered channel model whereby we sell our enterprise platform offerings to our distributors, which in turn sell to our resellers, which then sell to end users, which we call customers.
Many of our enterprise platform customers initially use either our free or paid version of Nessus, one of the industry’s most widely deployed vulnerability assessment solutions. Nessus, which is the technology that underpins our enterprise platform offerings, is designed to quickly and accurately identify vulnerabilities, configuration and compliance issues and malware. Our free version of Nessus, Nessus Essentials, allows for vulnerability assessment over a limited number of IP addresses. We believe many of our Nessus customers begin with Nessus Essentials and subsequently upgrade to Nessus Professional, the paid version of Nessus; however, we expect many users to continue to use Nessus Essentials.

1


Corporate Information
Tenable Network Security, Inc., our predecessor, was incorporated under the laws of the State of Delaware in 2002. Tenable Holdings, Inc. was incorporated in Delaware in October 2015, and in November 2015, Tenable Network Security, Inc. was merged into our wholly-owned indirect subsidiary and in 2017 was renamed as Tenable, Inc.
Our principal executive offices are located at 7021 Columbia Gateway Drive, Suite 500, Columbia, Maryland 21046. Our telephone number is (410) 872-0555. Our website address is www.tenable.com. Information found on, or accessible through, our website is not a part of, and is not incorporated into, this prospectus, and you should not consider it part of this prospectus or part of any prospectus supplement. Our website address is included in this prospectus as an inactive textual reference only.

2


RISK FACTORS
Investing in our common stock involves a high degree of risk. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, filed with the SEC on February 28, 2020, and our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, filed with the SEC on May 7, 2020, as updated by our subsequent annual, quarterly and other reports and documents that are incorporated by reference into this prospectus and the applicable prospectus supplement, before deciding whether to purchase the common stock being registered pursuant to the registration statement of which this prospectus is a part. The risks described in these documents are not the only ones we face, but those that we consider to be material. Additional risks and uncertainties that we are unaware of, or that we currently believe are not material, may also become important factors that adversely affect our business. Past financial performance may not be a reliable indicator of future performance, and historical trends should not be used to anticipate results or trends in future periods. If any of the risks actually occurs, it could adversely affect our business, operating results and financial condition, and could cause the trading price of our common stock to decline, which might cause you to lose all or part of your investment. Please also carefully read the section under the heading “Special Note Regarding Forward-Looking Statements.”

3


SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
Statements contained in this prospectus, the applicable prospectus supplement and in the documents incorporated by reference herein and therein that are not strictly historical in nature are forward-looking statements within the meaning of Section 27A of the Securities Act, and within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These statements relate to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These forward-looking statements are subject to the “safe harbor” created by Section 27A of the Securities Act and Section 21E of the Exchange Act and may include, but are not limited to, statements about:
the anticipated impact of the global economic uncertainty and financial market conditions caused by the COVID-19 pandemic on our business, results of operations and financial condition, including on our sales and our revenue growth rate;
our market opportunity;
the effects of increased competition as well as innovations by new and existing competitors in our market;
our ability to adapt to technological change, release new products and product features and effectively enhance, innovate and scale our enterprise platform and solutions;
our ability to effectively manage or sustain our growth and to achieve profitability;
our ability to maintain and expand our customer base, including by attracting new customers;
our relationships with third parties, including channel partners;
completed and potential acquisitions and integration of complementary businesses and technologies;
our ability to maintain, or strengthen awareness of, our brand;
perceived or actual problems with the security, integrity, reliability, compatibility and quality of our platform and solutions;
future revenue, hiring plans, expenses, capital expenditures, capital requirements and stock performance;
our ability to attract and retain qualified employees and key personnel and further expand our overall headcount;
our ability to stay abreast of new or modified laws and regulations that currently apply or become applicable to our business both in the United States and internationally;
our ability to maintain, protect and enhance our intellectual property;
costs associated with defending intellectual property infringement and other claims; and
the future trading prices of our common stock and the impact of securities analysts’ reports on these prices.

4


In some cases, you can identify forward-looking statements by terms such as “anticipates,” “believes,” “could,” “estimates,” “expects,” “goal,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would,” the negative of these words and words or similar expressions intended to identify forward-looking statements. These statements reflect our views as of the date on which they were made with respect to future events and are based on assumptions and subject to risks and uncertainties. The underlying information and expectations are likely to change over time. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date the statement is made, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.
Given these uncertainties, you should not place undue reliance on these forward-looking statements as actual events or results may differ materially from those projected in the forward-looking statements due to various factors, including, but not limited to, those set forth under the heading “Risk Factors” in any applicable prospectus supplement, the documents incorporated by reference therein or any free writing prospectus that we authorized. These forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements contained in this prospectus, in the documents incorporated by reference herein and in any prospectus supplement by these cautionary statements. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. Before deciding to purchase our common stock, you should carefully consider the risk factors discussed herein or incorporated by reference, in addition to the other information set forth in this prospectus, any accompanying prospectus supplement or free writing prospectus and in the documents incorporated by reference, with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

5


USE OF PROCEEDS
All shares of common stock offered by this prospectus and any applicable prospectus supplement will be sold by the selling stockholders. Unless the applicable prospectus supplement provides otherwise, we will not receive any of the proceeds from the sale of our common stock by selling stockholders.

6


DESCRIPTION OF CAPITAL STOCK
The following descriptions of our capital stock, certain provisions of our amended and restated certificate of incorporation and amended and restated bylaws and certain provisions of Delaware law are summaries. You should also refer to the amended and restated certificate of incorporation and the amended and restated bylaws, which are filed as exhibits to the registration statement of which this prospectus is a part.
Common Stock
Authorized Common Stock
The certificate of incorporation authorizes the issuance of up to 500,000,000 shares of common stock, $0.01 par value per share. As of June 30, 2020, there were 101,127,150 outstanding shares of common stock, including 296,753 shares of restricted common stock and excluding 11,058,465 shares of common stock issuable upon the exercise of outstanding options, at a weighted average exercise price of $8.53 per share, and 5,435,615 shares of common stock issuable upon the vesting of outstanding restricted stock units.
Voting Rights
Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Under the amended and restated certificate of incorporation and amended and restated bylaws, holders of common stock do not have cumulative voting rights. Because of this, the holders of a majority of the shares of common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they should so choose.
Dividends
Subject to preferences that may be applicable to any then outstanding preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by the board of directors out of legally available funds.
Liquidation
In the event of our liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of debts and other liabilities and the satisfaction of any liquidation preference granted to the holders of any then outstanding shares of preferred stock.
Rights and Preferences
Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that the board of directors may designate in the future.
Preferred Stock
Our board of directors has the authority, without further action by our stockholders, to fix the rights, preferences, privileges and restrictions of up to an aggregate of up to 10,000,000 shares of preferred stock in one or more series and authorize their issuance from time to time. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation

7


preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of our common stock. The issuance of our preferred stock could adversely affect the voting power of holders of our common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deterring or preventing a change of control or other corporate action.
As of the date of this prospectus, we have no preferred stock outstanding and no present plans to issue any preferred stock.
Registration Rights of Common Stock
Certain holders of shares of our common stock are entitled to certain rights with respect to registration of such shares under the Securities Act pursuant to the terms of an investor rights agreement and are described in additional detail below. These shares are collectively referred to herein as registrable securities.
The holders of registrable securities have waived their registration rights with respect to the filing of the registration statement of which this prospectus forms a part.
Demand Registration Rights
The holders of not less than 60% of the registrable securities then outstanding have the right to make a demand that we file a registration statement under the Securities Act covering registrable securities then outstanding having an aggregate offering price of at least $30 million, subject to specified exceptions.
Piggyback Registration Rights
If we register any securities for public sale, the holders of our registrable securities then outstanding will each be entitled to notice of the registration and will have the right to include their shares in the registration statement.
The underwriters of any underwritten offering will have the right to limit the number of shares having registration rights to be included in the registration statement, but not below 20% of the total number of securities included in such registration.
Registration on Form S-3
If we are eligible to file a registration statement on Form S-3, the holders of our registrable securities have the right to demand that we file registration statements on Form S-3; provided, that the aggregate price to the public of the securities to be sold under the registration statement is at least $10 million. The right to have such shares registered on Form S-3 is further subject to other specified conditions and limitations.
Expenses of Registration
We will pay all expenses relating to any demand, piggyback or Form S-3 registration, other than underwriting discounts and commissions, subject to specified conditions and limitations.
Termination of Registration Rights
The registration rights will terminate in July 2023, on the fifth anniversary of the closing date of our initial public offering and, with respect to any particular stockholder, if earlier when such stockholder is

8


able to sell all of his, her or its shares during a 90-day period pursuant to Rule 144 under the Securities Act.
Anti-Takeover Provisions
Section 203 of the Delaware General Corporation Law
We are subject to Section 203 of the Delaware General Corporation Law (Section 203) which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:
before such date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder;
upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction began, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the interested stockholder) those shares owned (1) by persons who are directors and also officers and (2) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or
on or after such date, the business combination is approved by the board of directors and authorized at an annual or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock that is not owned by the interested stockholder.
In general, Section 203 defines a “business combination” to include the following:
any merger or consolidation involving the corporation and the interested stockholder;
any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the interested stockholder;
subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;
any transaction involving the corporation that has the effect of increasing the proportionate share of the stock or any class or series of the corporation beneficially owned by the interested stockholder; or
the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits by or through the corporation.
In general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.
A Delaware corporation may “opt out” of these provisions with an express provision in its original certificate of incorporation or an express provision in its amended and restated certificate of incorporation or amended and restated bylaws resulting from a stockholders’ amendment approved by at least a

9


majority of the outstanding voting shares. We have not opted out of these provisions. As a result, mergers or other takeover or change in control attempts of us may be discouraged or prevented.
Anti-Takeover Effects of Certain Provisions of the Certificate of Incorporation and Bylaws
The amended and restated certificate of incorporation provides for our board of directors to be divided into three classes with staggered three-year terms. Only one class of directors will be elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms. Because our stockholders do not have cumulative voting rights, stockholders holding a majority of the shares of our common stock outstanding will be able to elect all of the directors. The amended and restated certificate of incorporation and the amended and restated bylaws also provide that directors may be removed by the stockholders only for cause upon the vote of 66 2/3% of our outstanding common stock. Furthermore, the authorized number of directors may be changed only by resolution of the board of directors, and vacancies and newly created directorships on the board of directors may, except as otherwise required by law or determined by the board, only be filled by a majority vote of the directors then serving on the board, even though less than a quorum.
The amended and restated certificate of incorporation and amended and restated bylaws also provide that all stockholder actions must be effected at a duly called meeting of stockholders and eliminates the right of stockholders to act by written consent without a meeting. The amended and restated bylaws provide that only the chairman of the board, chief executive officer or the board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors may call a special meeting of stockholders.
The amended and restated bylaws also provide that stockholders seeking to present proposals before a meeting of stockholders or to nominate candidates for election as directors at a meeting of stockholders must provide timely advance notice in writing, and specify requirements as to the form and content of a stockholder’s notice.
The amended and restated certificate of incorporation and amended and restated bylaws provide that the stockholders cannot amend many of the provisions described above except by a vote of 66 2/3% or more of our outstanding common stock.
The combination of these provisions will make it more difficult for our existing stockholders to replace the board of directors as well as for another party to obtain control of us by replacing the board of directors. Since the board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for the board of directors to issue preferred stock with voting or other rights or preferences that could delay or impede the success of any attempt to change control of us.
These provisions are intended to facilitate our continued innovation and the risk-taking that it requires, permit our board of directors to continue to prioritize our long-term goals rather than short-term results, enhance the likelihood of continued stability in the composition of the board of directors and its policies. These provisions could discourage potential takeover attempts. These provisions are also designed to reduce our vulnerability to an unsolicited acquisition proposal and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of deterring hostile takeovers or delaying changes in control or management. As a consequence, these provisions may also inhibit increases in the market price of our stock that could result from actual or rumored takeover attempts.

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Corporate Opportunities
The amended and restated certificate of incorporation provides that no officer or director of ours who is also an officer, director, managing director or other employee of Accel or Insight (each as defined below), will be liable to us or our stockholders for breach of any fiduciary duty by reason of the fact that any such individual directs a corporate opportunity to any member of Accel or Insight (including any portfolio company thereof), instead of to us, or does not communicate information regarding a corporate opportunity to us that the officer, director, employee, managing director or other affiliate has directed to any member of Accel or Insight (including any portfolio company thereof), unless such corporate opportunity is expressly offered to such officer or director in his or her capacity as an officer or director of our company.
“Accel” means Accel, together with its subsidiaries, certain investment funds affiliated with or managed by Accel, any other investment fund or collective investment vehicle affiliated with or managed by Accel or whose general partner or managing member is owned, directly or indirectly, by Accel and (iv) any affiliate of the foregoing (in each case, other than Tenable and its subsidiaries).
“Insight” means each of Insight Venture Management, LLC and Insight Holdings Group, LLC, together with all investment funds affiliated with or managed by any of them, any other investment fund or collective investment vehicle affiliated with or managed by any of them or whose general partner or managing member is owned, directly or indirectly, by any of them and (iv) any affiliate of the foregoing (in each case, other than Tenable and its subsidiaries).
Choice of Forum
Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware will be the exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a breach of fiduciary duty owed by any director, officer or other employee to us or our stockholders; (3) any action asserting a claim against us or any director or officer or other employee arising pursuant to the Delaware General Corporation Law, our amended and restated certificate of incorporation or amended and restated bylaws; or (4) any action asserting a claim against us or any director or officer or other employee that is governed by the internal affairs doctrine. This provision would not apply to suits brought to enforce a duty or liability created by the Exchange Act. Furthermore, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all such Securities Act actions. Accordingly, both state and federal courts have jurisdiction to entertain such claims. To prevent having to litigate claims in multiple jurisdictions and the threat of inconsistent or contrary rulings by different courts, among other considerations, our amended and restated certificate of incorporation further provides that the federal district courts of the United States of America will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act. While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions. In such instance, we would expect to vigorously assert the validity and enforceability of the exclusive forum provisions of our amended and restated certificate of incorporation. This may require significant additional costs associated with resolving such action in other jurisdictions and there can be no assurance that the provisions will be enforced by a court in those other jurisdictions.
Transfer Agent and Registrar
The transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC. The transfer agent’s address is 6201 15th Avenue, Brooklyn, New York 11219.
Listing
Our common stock is listed on The Nasdaq Global Select Market under the symbol “TENB.”

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MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES FOR NON-U.S. HOLDERS
The following is a discussion of certain material U.S. federal income tax considerations applicable to non-U.S. holders (as defined below) with respect to their ownership and disposition of shares of our common stock issued pursuant to this offering, but does not purport to be a complete analysis of all potential tax effects. All prospective non-U.S. holders of our common stock should consult their own tax advisors with respect to the U.S. federal income tax consequences of the purchase, ownership and disposition of our common stock, as well as any consequences arising under the laws of any other taxing jurisdiction, including any state, local and non-U.S. tax consequences and any U.S. federal non-income tax consequences. In general, a non-U.S. holder means a beneficial owner of our common stock (other than a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is not, for U.S. federal income tax purposes:
an individual who is a citizen or resident of the United States;
a corporation, or an entity treated as a corporation for U.S. federal income tax purposes, created or organized in the United States or under the laws of the United States or of any state thereof or the District of Columbia;
an estate, the income of which is subject to U.S. federal income tax regardless of its source; or
a trust if (1) a U.S. court can exercise primary supervision over the trust's administration and one or more U.S. persons have the authority to control all of the trust's substantial decisions or (2) the trust has a valid election in effect under applicable U.S. Treasury Regulations to be treated as a U.S. person.
This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, which we refer to as the Code, existing U.S. Treasury Regulations promulgated thereunder, published administrative rulings and judicial decisions, all as in effect as of the date of this prospectus supplement. These laws are subject to change and to differing interpretation, possibly with retroactive effect. Any change or differing interpretation could alter the tax consequences to non-U.S. holders described in this prospectus supplement.
This discussion is limited to non-U.S. holders that hold shares of our common stock as a capital asset within the meaning of Section 1221 of the Code (generally, for investment). This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular non-U.S. holder in light of that non-U.S. holder's individual circumstances, nor does it address any aspects of U.S. estate or gift tax, or any state, local or non-U.S. taxes. This discussion also does not consider any specific facts or circumstances that may apply to a non-U.S. holder and does not address all special tax rules applicable to particular non-U.S. holders, such as holders that own, or are deemed to own, more than 5% of our capital stock (except to the extent specifically set forth below), corporations that accumulate earnings to avoid U.S. federal income tax, tax-exempt organizations, banks, financial institutions, insurance companies, brokers, dealers or traders in securities, commodities or currencies, tax-qualified retirement plans, holders subject to the alternative minimum tax or Medicare contribution tax, holders who hold or receive our common stock pursuant to the exercise of employee stock options or otherwise as compensation, holders holding our common stock as part of a hedge, straddle or other risk reduction strategy, conversion transaction or other integrated investment, holders deemed to sell our common stock under the constructive sale provisions of the Code, persons subject to special tax accounting rules under Section 451(b) of the Code, “qualified foreign pension funds” as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds, controlled foreign corporations, passive foreign investment companies and certain former citizens or long-term residents of the United States.



In addition, this discussion does not address the tax treatment of partnerships (or entities or arrangements that are treated as partnerships for U.S. federal income tax purposes) or persons that hold their common stock through such partnerships or such entities or arrangements. If a partnership, including any entity or arrangement treated as a partnership for U.S. federal income tax purposes, holds shares of our common stock, the U.S. federal income tax treatment of a partner in such partnership will generally depend upon the status of the partner, the activities of the partnership and certain determinations made at the partner level. Such partners and partnerships should consult their tax advisors regarding the tax consequences of the purchase, ownership and disposition of our common stock.
There can be no assurance that the Internal Revenue Service, which we refer to as the IRS, will not challenge one or more of the tax consequences described herein, and we have not obtained, nor do we intend to obtain, a ruling with respect to the U.S. federal income tax consequences with respect to the matters discussed below.
Distributions on Our Common Stock
As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying distributions to holders of our common stock in the foreseeable future. However, distributions, if any, on our common stock generally will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder's investment, up to such holder's adjusted tax basis in the common stock. Any remaining excess will be treated as capital gain from the sale or exchange of such common stock, subject to the tax treatment described below in “Gain on Sale, Exchange or Other Disposition of Our Common Stock.”
Subject to the discussions below regarding effectively connected income, dividends paid to a non-U.S. holder will generally be subject to withholding of U.S. federal income tax at a 30% rate, or such lower rate as may be specified by an applicable income tax treaty. A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty generally will be required to provide a properly executed IRS Form W-8BEN or W-8BEN-E (or other appropriate form), certifying the non-U.S. holder’s entitlement to benefits under that treaty. This certification must be provided to us or our paying agent prior to the payment of dividends and must be updated periodically. In the case of a non-U.S. Holder that is an entity, Treasury Regulations and the relevant tax treaty provide rules to determine whether, for purposes of determining the applicability of a tax treaty, dividends will be treated as paid to the entity or to those holding an interest in that entity. If a non-U.S. holder holds stock through a financial institution or other agent acting on the holder’s behalf, the non-U.S. holder will be required to provide appropriate documentation to such agent. The non-U.S. holder’s agent will then be required to provide certification to us or our paying agent, either directly or through intermediaries. If you are eligible for a reduced rate of U.S. federal withholding tax under an income tax treaty and you do not timely file the required certification, you may be able to obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty.
Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification requirements. To claim the exemption, the non-U.S. holder must furnish to us or the applicable withholding agent a valid IRS Form W-8ECI (or applicable successor form), certifying that the dividends are effectively connected with the non-U.S. holder's conduct of a trade or business within the United States. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same U.S. federal income tax rates applicable to U.S. persons (as defined in the Code),



unless a specific treaty exemption applies. Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty.
Gain on Sale, Exchange or Other Disposition of Our Common Stock
Subject to the discussions below regarding backup withholding and foreign accounts, in general, a non-U.S. holder will not be subject to any U.S. federal income tax on any gain realized upon such holder's sale, exchange or other disposition of shares of our common stock unless:
the gain is effectively connected with a U.S. trade or business of the non-U.S. holder and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed base maintained in the United States by such non-U.S. holder, in which case the non-U.S. holder generally will be taxed at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code) and, if the non-U.S. holder is a foreign corporation, the branch profits tax described above in “Distributions on Our Common Stock” may also apply;
the non-U.S. holder is a nonresident alien individual who is present in the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the non-U.S. holder will be subject to a 30% tax (or such lower rate as may be specified by an applicable income tax treaty) on the net gain derived from the disposition, which may be offset by certain U.S. source capital losses of the non-U.S. holder, if any (even though the individual is not considered a resident of the United States), provided the non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses; or
our common stock constitutes a U.S. real property interest because we are, or have been, at any time during the five-year period preceding such disposition (or the non-U.S. holder's holding period, if shorter) a “U.S. real property holding corporation.” Even if we are or become a U.S. real property holding corporation, provided that our common stock is regularly traded on an established securities market, our common stock will be treated as a U.S. real property interest only with respect to a non-U.S. holder that holds more than 5% of our outstanding common stock, directly or indirectly, actually or constructively, during the shorter of the five-year period ending on the date of the disposition or the period that the non-U.S. holder held our common stock. In such case, such non-U.S. holder generally will be taxed on its net gain derived from the disposition at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code). Generally, a corporation is a U.S. real property holding corporation only if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one in the future. No assurance can be provided that our common stock will be regularly traded on an established securities market for purposes of the rules described above.
Backup Withholding and Information Reporting
We must report annually to the IRS and to each non-U.S. holder the gross amount of distributions on our common stock paid to such holder, regardless of whether such distributions constitute dividends or whether any tax was actually withheld. Non-U.S. holders will have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate (currently 24%) with respect to dividends on our common stock. U.S. backup withholding generally will not apply to a non-U.S. holder who provides a properly executed IRS Form W-8BEN or W-8BEN-E or otherwise establishes an exemption.



Information reporting and backup withholding will generally apply to the proceeds of a disposition of our common stock by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker.
Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them.
Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement.
Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder may be allowed as a credit against the non-U.S. holder's U.S. federal income tax liability, if any, and may entitle such holder to a refund, provided that the required information is timely furnished to the IRS.
Foreign Accounts
Sections 1471 through 1474 of the Code (commonly referred to as FATCA) generally impose a U.S. federal withholding tax of 30% on certain payments made to a “foreign financial institution” (as specifically defined for this purpose), unless such institution enters into an agreement with the U.S. government to, among other things, withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding U.S. account holders of such institution (which may include certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners). Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing these withholding and reporting requirements may be subject to different rules. FATCA also generally imposes a 30% withholding tax on certain payments made to a non-financial foreign entity, unless such entity provides the withholding agent with either a certification that it does not have any substantial direct or indirect U.S. owners or information regarding substantial direct and indirect U.S. owners of the entity. The withholding tax under FATCA described above will not apply if the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from the rules. The FATCA withholding provisions described above currently apply to dividends on our common stock. The FATCA withholding provisions also would apply to the gross proceeds of a disposition of our common stock, except that the U.S. Treasury Department has released proposed regulations which, if finalized in their present form, would eliminate such withholding. In its preamble to such proposed regulations, the U.S. Treasury Department stated that taxpayers generally may rely on the proposed regulations until final regulations are issued.
Under certain circumstances, a non-U.S. holder might be eligible for refunds or credits of such taxes. Non-U.S. holders are encouraged to consult with their tax advisors regarding the possible implications of FATCA on their investment in our common stock.
EACH PROSPECTIVE INVESTOR SHOULD CONSULT ITS OWN TAX ADVISOR REGARDING THE TAX CONSEQUENCES OF PURCHASING, HOLDING AND DISPOSING OF OUR COMMON STOCK, AS WELL AS TAX CONSEQUENCES ARISING UNDER ANY STATE, LOCAL, NON-U.S. OR U.S. FEDERAL NON-INCOME TAX LAWS.



SELLING STOCKHOLDERS
The selling stockholders identified in this prospectus are holders of our common stock originally acquired in connection with our initial public offering, or IPO, upon conversion of preferred stock purchased by such stockholders in private financings that we conducted prior to our IPO. Our director, Richard M. Wells, is a Managing Director at Insight Venture Management, LLC, an entity affiliated with the Insight Partners.
We are party to an investors’ rights agreement with the selling stockholders named in this prospectus, which provides the selling stockholders and the other holders of our common stock party thereto with certain rights with respect to the registration of shares of common stock held by them under the Securities Act. Additional information regarding such registration rights is contained under the heading “Description of Capital Stock–Registration Rights.”
Except for the ownership of the shares of common stock that may be offered and sold by the selling stockholders, the participation in the transactions described above, the investors’ rights agreement and the position that Mr. Wells holds on our board of directors, the selling stockholders have not had any material relationship with us or our affiliates within the past three years.
The table below, including the footnotes, sets forth the selling stockholders and other information regarding the beneficial ownership of the shares of common stock held by each of the selling stockholders based on information provided to us by the selling stockholders. Generally, a person “beneficially owns” shares of our common stock if the person has or shares with others the right to vote those shares or to dispose of them, or if the person has the right to acquire voting or disposition rights within 60 days. The percent of shares beneficially owned prior to and after the offering is based on 101,263,716 shares of our common stock issued and outstanding as of July 24, 2020.
Name of Selling Stockholder
 
Shares Beneficially Owned
 
Maximum
Number of
Shares to be
Sold
 
Hereunder
 
Shares Beneficially Owned after
the Sale of the Maximum
Number of Shares
 
Number
 
Percentage
 
 
Number
 
Percentage
Entities affiliated with Insight Partners(1)
 
22,333,780

 
22.1%
 
22,333,780

 

 
________________
(1)
Consists of (a) 6,873,043 shares of common stock held by Insight Venture Partners IX, L.P., or IVP IX, (b) 3,415,047 shares of common stock held by Insight Venture Partners (Cayman) IX, L.P., or IVP (Cayman) IX, (c) 728,197 shares of common stock held by Insight Venture Partners (Delaware) IX, L.P., or IVP (Delaware) IX, (d) 137,191 shares of common stock held by Insight Venture Partners IX (Co-Investors), L.P., or IVP IX (Co-Investors), and, collectively with IVP IX, IVP (Cayman) IX and IVP (Delaware) IX, the “IVP IX Funds”, (e) 25,699 shares of common stock held by IVP (Venice), L.P., or IVP Venice, (f) 3,230,422 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund, L.P., or IVP Coinvestment, (g) 2,597,069 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (Cayman), L.P., or IVP Coinvestment (Cayman), (h) 2,388,016 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (Delaware), L.P., or IVP Coinvestment (Delaware), and (i) 2,939,096 shares of common stock held by Insight Venture Partners Growth-Buyout Coinvestment Fund (B), L.P., or IVP Coinvestment (B), and, collectively with IVP Coinvestment, IVP Coinvestment (Cayman) and IVP Coinvestment (Delaware), the “IVP Coinvestment Funds” and, together with the IVP IX Funds and IVP Venice, the “IVP Funds.” Insight Venture Associates IX, Ltd., or IVA IX Ltd., is the general partner of Insight Venture Associates IX, L.P., which is the general partner of each of the IVP IX Funds. Insight Venture Associates Growth-Buyout Coinvestment, Ltd., or IVA Coinvestment Ltd., is the general partner of Insight Venture Associates Growth-Buyout Coinvestment, L.P., which is the general partner of each of the IVP Coinvestment Funds. Insight Holdings Group, LLC, or Insight Holdings, is the sole shareholder of each of IVA IX Ltd., and IVA Coinvestment Ltd, Insight Holdings is the sole shareholder of Insight Venture Associates X, Ltd., which is the general partner of IVP GP (Venice), which in turn is the manager of IVP Venice. Each of Jeffrey L. Horing, Deven Parekh, Peter Sobiloff, Jeffrey Lieberman and Michael Triplett is a member of the board of managers of Insight Holdings and as such may be deemed to have shared voting and dispositive power over the shares held by each of the IVP Funds. Richard M. Wells is a Managing Director at Insight Venture Management, LLC, an entity affiliated with the IVP Funds, but does not have voting and dispositive power over the shares held by IVP Funds. The principal business address for all entities and individuals affiliated with Insight Partners is c/o Insight Partners, 1114 Avenue of the Americas, 36th Floor, New York, New York, 10036.

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PLAN OF DISTRIBUTION
The selling stockholders may sell common stock from time to time pursuant to underwritten public offerings, “at the market” offerings, negotiated transactions, block trades or a combination of these methods. The selling stockholders may sell common stock to or through underwriters or dealers, through agents, or directly to one or more purchasers, including through a specific bidding, auction or other process. The selling stockholders may distribute common stock from time to time in one or more transactions:
at a fixed price or prices, which may be changed;
at market prices prevailing at the time of sale;
at prices related to such prevailing market prices; or
at negotiated prices.
A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you), if required, will describe the terms of the offering of the common stock, including, to the extent applicable:
the name or names of any underwriters, dealers or agents, if any;
the name or names of the selling stockholders;
the purchase price of the common stock;
any over-allotment options under which underwriters may purchase additional common stock from the selling stockholders;
any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;
any public offering price;
any discounts or concessions allowed or reallowed or paid to dealers; and
any securities exchange or market on which the common stock is listed.
In effecting sales, brokers or dealers engaged by us and/or the selling stockholders may arrange for other brokers or dealers to participate. Broker/dealer transactions may include:
purchases of the shares of common stock by a broker-dealer as principal and resales of the shares of common stock by the broker-dealer for its account pursuant to this prospectus;
ordinary brokerage transactions; or
transactions in which the broker/dealer solicits purchasers on a best efforts basis.
Only underwriters named in the prospectus supplement will be underwriters of the common stock offered by the prospectus supplement.
If underwriters are used in the sale, they will acquire the common stock for their own account and may resell the common stock from time to time in one or more transactions at a fixed public offering price

17


or at varying prices determined at the time of sale. The obligations of the underwriters to purchase common stock will be subject to the conditions set forth in the applicable underwriting agreement. The selling stockholders may offer common stock to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the shares of common stock offered by the prospectus supplement. If a dealer is used in the sale of common stock, a selling stockholder or an underwriter will sell the common stock to the dealer, as principal. The dealer than may resell the common stock to the public at varying prices to be determined by the dealer at the time of resale. To the extent required, we will set forth in the prospectus supplement the name of the dealer and the terms of the transaction. Any public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may change from time to time.
The selling stockholders may use underwriters with whom we have a material relationship. To the extent required, we will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.
The selling stockholders may sell common stock directly or through agents designated from time to time. To the extent required, we will name any agent involved in the offering and sale of the common stock, and we will describe any commissions paid to the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, the agent will act on a best-efforts basis for the period of its appointment.
The selling stockholders may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase common stock from the selling stockholders at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. To the extent required, we will describe the conditions to these contracts and the commissions the selling stockholders must pay for solicitation of these contracts in the prospectus supplement.
We and the selling stockholders may provide agents, underwriters and dealers with indemnification against civil liabilities , including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents, underwriters and dealers may engage in transactions with, or perform services for, us in the ordinary course of business.
Selling stockholders may be deemed to be underwriters under the Securities Act in connection with the common stock they resell and any profits on the sales may be deemed to be underwriting discounts and commissions under the Securities Act.
Any underwriters may make a market in our common stock, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for our common stock.
Any underwriter may engage in over-allotment, stabilizing transactions, short-covering transactions and penalty bids. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short-covering transactions involve purchases of the common stock in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the common stock originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the common stock to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time. These transactions may be effected on any exchange or over-the-counter market or otherwise.

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Any underwriters who are qualified market makers on The Nasdaq Global Select Market may engage in passive market making transactions in the common stock on The Nasdaq Global Select Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for shares of the common stock; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the common stock at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.
The underwriters, dealers and agents may engage in transactions with us, or perform services for us, in the ordinary course of business for which they receive compensation.
Some of the shares of common stock covered by this prospectus may be sold by selling stockholders in private transactions or under Rule 144 under the Securities Act rather than pursuant to this prospectus.

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LEGAL MATTERS
Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the common stock offered by this prospectus, and any prospectus supplement thereto, will be passed upon by Cooley LLP, Reston, Virginia. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.
EXPERTS
Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2019, and the effectiveness of our internal control over financial reporting as of December 31, 2019, (excluding the internal control over financial reporting of Indegy, Inc.) as set forth in their reports, which are incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s reports, given on their authority as experts in accounting and auditing.
WHERE YOU CAN FIND MORE INFORMATION
This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the common stock offered under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. Neither we or any selling stockholder nor any agent, underwriter or dealer has authorized any person to provide you with different information. We are not making an offer of securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the common stock offered by this prospectus.
We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including Tenable Holdings, Inc. The address of the SEC website is www.sec.gov.
Copies of certain information filed by us with the SEC are also available on our website at www.tenable.com. Information contained in or accessible through our website does not constitute a part of this prospectus and is not incorporated by reference into this prospectus.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus. We incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information or documents listed below that we have filed with the SEC (Commission File No. 001-38600):
our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, filed with the SEC on February 28, 2020;
our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, filed with the SEC on May 7, 2020;
our Current Reports on Form 8-K filed with the SEC on June 3, 2020 and July 28, 2020 (Item 1.01) (as to information therein explicitly filed with the SEC only);
the information specifically incorporated by reference into our Annual Report on Form 10-K for the fiscal year ended December 31, 2019 from our Definitive Proxy Statement on Schedule 14A, filed with the SEC on April 15, 2020; and
the description of our common stock in our registration statement on Form 8-A filed with the SEC on July 20, 2018, including any amendments thereto or reports filed for the purposes of updating this description.
We also incorporate by reference into this prospectus any future filings made by us with the SEC (other than Current Reports or portions thereof furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items and other portions of documents that are furnished, but not filed, pursuant to applicable rules promulgated by the SEC) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the filing and concurrent effectiveness of the registration statement but prior to the termination of all offerings covered by this prospectus. Information in such future filings updates and supplements the information provided in this prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.
We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits which are specifically incorporated by reference into such documents. You should direct any requests for documents to the following address or phone number:
Tenable Holdings, Inc.
7021 Columbia Gateway Drive, Suite 500
Columbia, Maryland 21046
(410) 872-0555
Attention: Corporate Secretary

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