X0306 4 2020-10-21 0 0001561550 Datadog, Inc. DDOG 0001784030 Callahan Michael James C/O DATADOG, INC. 620 8TH AVENUE, 45TH FLOOR NEW YORK NY 10018 1 0 0 0 Class A Common Stock 2020-10-21 4 C 0 11000 0.00 A 56459 I By Trust Class A Common Stock 2020-10-21 4 S 0 2961 99.392 D 53498 I By Trust Class A Common Stock 2020-10-21 4 S 0 3695 100.2713 D 49803 I By Trust Class A Common Stock 2020-10-21 4 S 0 1749 101.4009 D 48054 I By Trust Class A Common Stock 2020-10-21 4 S 0 1195 102.5008 D 46859 I By Trust Class A Common Stock 2020-10-21 4 S 0 400 103.2525 D 46459 I By Trust Class A Common Stock 20000 I By GRAT Class B Common Stock 2020-10-21 4 C 0 11000 0.00 D Class A Common Stock 11000 346606 I By Trust Class B Common Stock Class A Common Stock 80000 80000 I By GRAT Class B Common Stock Class A Common Stock 100000 100000 I By GRAT Each share of Class B Common Stock is convertible at any time at the option of the Reporting Person into one share of Class A Common Stock and has no expiration date. Each share of Class B Common Stock will convert automatically into one share of Class A Common Stock upon the earliest of: (i) any transfer, whether or not for value, except for certain "Permitted Transfers" as defined in the Issuer's amended and restated certificate of incorporation, (ii) the death of the Reporting Person in the case of shares held directly or in a trustee capacity, and (iii) the tenth anniversary of the Issuer's initial public offering of its Class A Common Stock. The Shares are held by The Callahan-Thernstrom Family Trust, of which Reporting Person is Trustee. Shares sold pursuant to a 10b5-1 plan entered into on June 14, 2020. Price reported is a weighted-average sales price. The shares were sold at prices ranging from $98.86 to $99.83. The Reporting Person will provide upon request to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price. Price reported is a weighted-average sales price. The shares were sold at prices ranging from $99.88 to $100.81. The Reporting Person will provide upon request to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price. Price reported is a weighted-average sales price. The shares were sold at prices ranging from $101.00 to $101.785. The Reporting Person will provide upon request to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price. Price reported is a weighted-average sales price. The shares were sold at prices ranging from $102.02 to $102.91. The Reporting Person will provide upon request to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price. Price reported is a weighted-average sales price. The shares were sold at prices ranging from $103.04 to $103.44. The Reporting Person will provide upon request to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price. Shares are held by The Michael Callahan Grantor Retained Annuity Trust, of which Reporting Person is Trustee. Shares are held directly by The Melanie Thernstrom Grantor Retained Annuity Trust, of which Reporting Person's spouse is Trustee. Michael James Callahan, by /s/ Ron A. Metzger, Attorney-in-Fact 2020-10-23