Sec Form 3 Filing - Shah Shardul @ Datadog, Inc. - 2019-09-18

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Shah Shardul 2. Issuer Name and Ticker or Trading Symbol Datadog, Inc. [ DDOG] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O DATADOG, INC., 620 8TH AVENUE, 45TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/18/2019 (Street) NEW YORK, NY10018 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 853,776 ( 1 ) ( 2 ) I See footnote ( 3 ) Common Stock 13,002 ( 1 ) ( 2 ) I See footnote ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series Seed Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 2,897,346 I See footnote ( 3 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 221,328 I See footnote ( 3 ) Series C Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 835,680 I See footnote ( 3 ) Series D Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 8,288,724 I See footnote ( 3 ) Series A Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 19,356,168 I See footnote ( 5 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 7,259,472 I See footnote ( 5 ) Series C Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 10,949,568 I See footnote ( 5 ) Series D Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 1,350,528 I See footnote ( 5 ) Series A Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 390,708 I See footnote ( 6 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 146,532 I See footnote ( 6 ) Series C Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 221,016 I See footnote ( 6 ) Series D Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 27,264 I See footnote ( 6 ) Series Seed Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 44,121 I See footnote ( 4 ) Series A Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 249,960 I See footnote ( 4 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 97,104 I See footnote ( 4 ) Series C Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 154,128 I See footnote ( 4 ) Series D Preferred Stock ( 1 ) ( 1 ) ( 1 ) See footnotes ( 1 ) ( 2 ) 143,652 I See footnote ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Shah Shardul C/O DATADOG, INC. 620 8TH AVENUE, 45TH FLOOR NEW YORK, NY10018 X Signatures Shardul Shah, by /s/ Ron A. Metzger, Attorney-in-Fact 09/18/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Preferred Stock is convertible into Common Stock on a 1:1 basis and has no expiration date. Immediately prior to the closing of the Issuer's initial public offering, (1) all shares of Preferred Stock will be automatically converted into shares of Common Stock on a 1:1 basis and (2) all shares of Common Stock shall then be reclassified into one share of Class B Common Stock on a 1:1 basis. ( 2 )After the completion of the Issuer's initial public offering, on any transfer of shares of Class B common stock, whether or not for value, each such transferred share will automatically convert into one share of Class A common stock, except for certain transfers described in the Issuer's amended and restated certificate of incorporation, including transfers for tax and estate planning purposes, so long as the transferring holder continues to hold sole voting and dispositive power with respect to the shares transferred. Additionally, the shares of Class B common stock will convert automatically into Class A common stock, on a 1:1 basis, upon the tenth anniversary of the Issuer's initial public offering. ( 3 )The shares are held by Index Ventures Growth III (Jersey), L.P. ("Index Growth III"). Index Venture Growth Associates III Limited ("IVGA III") is the managing general partner of Index Growth III. The Reporting Person is a partner within the Index Ventures group. Advisors within the Index Ventures group provide advice to each of Index Growth III, Index Ventures VI (Jersey) L.P. ("Index VI"), and Index Ventures VI Parallel Entrepreneur Fund (Jersey), L.P. ("Index VI Parallel" and together with Index Growth III and Index VI, the "Funds"). The Reporting Person disclaims Section 16 beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for Section 16 or any other purpose. ( 4 )The shares are held by Yucca (Jersey) SLP ("Yucca"). Yucca is the administrator of the Index co-investment vehicles that are contractually required to mirror the relevant Fund's investment in the issuer (in this case, Index Growth III, Index VI and Index VI Parallel). The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose. ( 5 )The shares are held by Index VI. Index Venture Associates VI Limited ("IVA VI") is the managing general partner of Index VI. The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose. ( 6 )The shares are held by Index VI Parallel. IVA VI is the managing general partner of Index VI Parallel. The Reporting Person disclaims Section 16 beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for Section 16 or any other purpose.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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