144 0001540517 XXXXXXXX LIVE 0001561550 Datadog, Inc. 001-39051 620 8th Avenue, 45th Floor New York NY 10018 8663294466 A-J-M 2025 NON-EXEMPT TRUST U/A DTD 09/12/2025 Affiliate Class A Common Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 8th Floor New York NY 10004

11112 1578459.60 325443373 12/16/2025 NASDAQ Class A Common 09/12/2025 Gift Agarwal 2018 Family Trust Y 04/07/2021 11112 NA N 10b5-1 Sales for AGARWAL 2018 FAMILY TRUST

620 8th Avenue, 45th Floor New York NY 10018

Class A Common 10/01/2025 45444 6820140.09 10b5-1 Sales for AGARWAL 2018 FAMILY TRUST

620 8th Avenue, 45th Floor New York NY 10018

Class A Common 09/18/2025 18 2434.14 10b5-1 Sales for AGARWAL 2018 FAMILY TRUST

620 8th Avenue, 45th Floor New York NY 10018

Class A Common 09/17/2025 10094 1356208.64 The shares to be sold pursuant to this Form are held by trusts set up for the benefit of the family of Amit Agarwal, a member of the board of directors of Datadog, Inc. The disposition of these shares is controlled by an independent trustee. The shares were acquired by the donor during the period 04/07/2021 through 07/14/2021. 12/16/2025 09/15/2025 /s/ Brian Cyr