SCHEDULE 13D/A 0000902664-22-003160 0001410830 XXXXXXXX LIVE 3 Common Stock, par value $0.001 per share 12/30/2025 false 0001725160 98943L107 Zentalis Pharmaceuticals, Inc.

10275 SCIENCE CENTER DRIVE SUITE 200 SAN DIEGO CA 92121

Gregory A. Brown (603) 956-9145 Matrix Capital Management Company LP 3 Pleasant Street, Suite 400 Portsmouth NH 03801 Ele Klein & Adriana Schwartz 212-756-2000 McDermott Will & Schulte LLP 919 Third Avenue New York NY 10022 0001410830 N Matrix Capital Management Company, LP OO N DE 0.00 0.00 0.00 0.00 0.00 N 0 IA PN 0001548144 N David E. Goel OO N X1 0.00 0.00 0.00 0.00 0.00 N 0 IN HC Common Stock, par value $0.001 per share Zentalis Pharmaceuticals, Inc. 10275 SCIENCE CENTER DRIVE SUITE 200 SAN DIEGO CA 92121 The following constitutes Amendment No. 3 ("Amendment No. 3") to the Schedule 13D filed by the undersigned on June 3, 2022 (the "Original Schedule 13D"), as amended by Amendment No. 1 filed by the undersigned with the Securities and Exchange Commission on June 20, 2023 ("Amendment No. 1") and Amendment No. 2 filed by the undersigned with the Securities and Exchange Commission on December 15, 2025 ("Amendment No. 2" and the Original Schedule 13D as amended by Amendment No. 1, Amendment No. 2 and this Amendment No. 3, the "Schedule 13D"). This Amendment No. 3 amends and restates Item 5. Capitalized terms used herein and not otherwise defined in this Amendment No. 3 have the meanings set forth in the Schedule 13D. This Amendment No. 3 is the final amendment to the Schedule 13D and constitutes an "exit filing" for the Reporting Persons. See rows (11) and (13) of the cover pages to this Schedule 13D for the aggregate number of shares of Common Stock and percentages of the shares of Common Stock beneficially owned by each Reporting Person. See rows (7) through (10) of the cover pages to this Schedule 13D for the number of shares of Common Stock as to which each Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition. On December 30, 2025, the Matrix Fund agreed to privately sell 6,459,973 shares of Common Stock to an accredited investor at a price of $1.20 per share (the "Private Sale"). The Private Sale closed on December 31, 2025. Except for the Private Sale, no transactions in the shares of Common Stock have been effected by the Reporting Persons since the filing of Amendment No. 2. Not applicable. December 30, 2025. Matrix Capital Management Company, LP /s/ Gregory A. Brown 01/02/2026 David E. Goel /s/ David E. Goel 01/02/2026