X0306 4 2020-02-24 0 0001561550 Datadog, Inc. DDOG 0001591294 Yucca (Jersey) SLP 5TH FLOOR, 44 ESPLANADE ST. HELIER Y9 JE1 3FG JERSEY 0 0 1 0 0001785453 Index Venture Growth Associates III Ltd 5TH FLOOR, 44 ESPLANADE ST. HELIER Y9 JE1 3FG JERSEY 0 0 1 0 0001755035 Index Venture Associates VI Ltd 5TH FLOOR, 44 ESPLANADE ST. HELIER Y9 JE1 3FG JERSEY 0 0 1 0 Class A Common Stock 2020-02-24 4 S 0 700 42.70 D 137808 D Class A Common Stock 2020-02-24 4 S 0 3500 43.97 D 134308 D Class A Common Stock 2020-02-24 4 S 0 63765 44.98 D 70543 D Class A Common Stock 2020-02-24 4 S 0 800 45.31 D 69743 D Class A Common Stock 2020-02-25 4 S 0 23401 43.64 D 46342 D Class A Common Stock 2020-02-25 4 S 0 42142 44.46 D 4200 D Class A Common Stock 2020-02-25 4 S 0 4200 45.30 D 0 D Class A Common Stock 1 D On February 24, 2020, Yucca (Jersey) SLP ("Yucca") sold 700 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $42.50 - $43.00. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares are held by Yucca. Yucca is the administrator of the Index co-investment vehicles that are contractually required to mirror the relevant Index fund's investment in the Issuer (in this case, Index Ventures Growth III (Jersey), L.P. ("Index Growth III", Index Ventures VI (Jersey), L.P. ("Index VI") and Index Ventures VI Parallel Entrepreneur Fund (Jersey), L.P. ("Index VI Parallel")). Index Venture Growth Associates III Limited ("IVGA III") is the general partner of Index Growth III and Index Venture Associates VI Limited ("IVA VI") is the general partner of Index VI. Each of IVGA III and IVA VI disclaims Section 16 beneficial ownership of such shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that such shares are beneficially owned by it for Section 16 or any other purpose. On February 24, 2020, Yucca sold 3,500 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $43.18 - $44.15. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. On February 24, 2020, Yucca sold 63,765 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $44.29 - $45.27. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. On February 24, 2020, Yucca sold 800 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $45.29 - $45.33. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. On February 25, 2020, Yucca sold 23,401 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $43.06 - $44.05. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. On February 25, 2020, Yucca sold 42,412 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $44.06 - $45.01. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. On February 25, 2020, Yucca sold 4,200 shares of the Issuer's Class A Common Stock. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $45.07 - $45.52. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. This share is held by Index VI. IVA VI disclaims Section 16 beneficial ownership of such share except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that such share is beneficially owned by it for Section 16 or any other purpose. Yucca (Jersey) SLP, By Intertrust Employee Benefit Services Limited, as authorized signatory of Yucca (Jersey) SLP in its capacity as Administrator of the Index Co-Investment Scheme, By: /s/ Sarah Earles, /s/ Nick McHardy, Its: Authorized Signatories 2020-02-26 Index Venture Growth Associates III Limited, By: /s/ Sinead Meehan, Its: Director 2020-02-26 Index Venture Associates VI Limited, By: /s/ Nigel Greenwood, Its: Director 2020-02-26