X0202 SCHEDULE 13D/A 0001079973-25-000383 0002060465 XXXXXXXX LIVE 5 Common Stock, par value $0.0001 per share 07/14/2026 false 0001854270 816944102 Senti Biosciences Holdings, Inc.

2 CORPORATE DRIVE, FIRST FLOOR SOUTH SAN FRANCISCO CA 94080

Lin-Chun Huang 806-807-8889 PO Box 500, Suite 210, 2nd Floor, Windward III Regatta Office Park Grand Cayman E9 KY1-1106 Eleazer Klein, Esq. 212-756-2000 McDermott Will & Schulte LLP 919 Third Avenue New York NY 10022 0002060465 N Celadon Partners SPV 24 OO N E9 0.00 25748890.00 0.00 25748890.00 25748890.00 N 54.6 OO Includes 15,971,890 shares of issuable upon the exchange of the Initial Notes (as defined in Item 3 of the Schedule 13D) issued on May 20, 2026, assuming the requisite stockholder approval of the Issuer's stockholders is obtained, and immediate exchange of such Initial Notes for Common Stock pursuant to the Securities Purchase Agreement (as defined in Item 3 of the Schedule 13D). Y Celadon Partners, LLC OO N E9 0.00 25748890.00 0.00 25748890.00 25748890.00 N 54.6 OO Includes 15,971,890 shares of Common Stock issuable upon the exchange of the Initial Notes (as defined in Item 3 of the Schedule 13D) issued on May 20, 2026, assuming the requisite stockholder approval of the Issuer's stockholders is obtained, and immediate exchange of such Initial Notes for Common Stock pursuant to the Securities Purchase Agreement (as defined in Item 3 of the Schedule 13D). Y CPIF II-7 Limited OO N E9 0.00 25748890.00 0.00 25748890.00 25748890.00 N 54.6 OO Includes 15,971,890 shares of Common Stock issuable upon the exchange of the Initial Notes (as defined in Item 3 of the Schedule 13D) issued on May 20, 2026, assuming the requisite stockholder approval of the Issuer's stockholders is obtained, and immediate exchange of such Initial Notes for Common Stock pursuant to the Securities Purchase Agreement (as defined in Item 3 of the Schedule 13D). Common Stock, par value $0.0001 per share Senti Biosciences Holdings, Inc. 2 CORPORATE DRIVE, FIRST FLOOR SOUTH SAN FRANCISCO CA 94080 The following constitutes Amendment No. 5 ("Amendment No. 5") to the Schedule 13D filed with the Securities and Exchange Commission on March 13, 2025 (as amended, the "Schedule 13D"). This Amendment No. 5 supplements Items 3, 4, 6 and 7 as set forth below. Capitalized terms used herein and not otherwise defined in this Amendment No. 5 have the meanings set forth in the Schedule 13D. On July 14, 2026, Senti Biosciences Holdings, Inc. (the "Issuer"), Senti Holdings, Inc. ("Midco"), Senti Biosciences, Inc. ("Opco"), Celadon Partners SPV 35 Limited ("Parent"), and Senti Merger Sub, Inc. ("Merger Sub") entered into an Agreement and Plan of Merger (the "Merger Agreement"). Parent is an exempted company incorporated under the laws of the Cayman Islands and is an entity affiliated with Celadon Partners SPV 24. Pursuant to the Merger Agreement, Merger Sub will merge with and into Midco (the "Merger"), with Midco surviving as a wholly owned subsidiary of Parent. At the effective time of the Merger, each outstanding share of Midco common stock (other than shares owned by Midco or its subsidiaries, which will be cancelled) will be cancelled and converted into the right to receive contingent value rights ("CVRs") representing the right to receive pro rata portions of milestone payments of up to $60 million in the aggregate if certain development, regulatory and commercial milestones for SENTI-202 are achieved. Pursuant to the Merger Agreement, no later than twenty-one (21) days from the date of the Merger Agreement, Parent or an affiliate of Parent is required to fund and purchase Additional Notes (as defined in the Securities Purchase Agreement) in accordance with the terms of the Securities Purchase Agreement, in an amount equal to $6,000,000 (the "Additional Funding Amount"), minus the aggregate amount of net proceeds actually received by the Issuer from sales of the Issuer's common stock pursuant to the Issuer's existing at-the-market offering facility with Leerink Partners LLC (the "ATM Facility"). Parent has the right, in its sole discretion, to first direct the Issuer to sell shares of common stock pursuant to the ATM Facility, and net proceeds received will reduce, dollar-for-dollar, the Additional Funding Amount. The foregoing description of the Merger Agreement is qualified in its entirety by reference to the Merger Agreement, a copy of which is filed as Exhibit H hereto and is incorporated by reference in this Item 3. The Reporting Persons and their affiliates entered into the Merger Agreement for the purpose of acquiring the Issuer's assets relating to its Gene-Circuit-enabled pipeline, including the rights to SENTI-202, through the Merger. Following the Merger, the Issuer is expected to remain a public company with a streamlined operating structure, retaining certain intellectual property, collaborations and early-stage programs focused on its Regulator Dial(TM) technology platform while the remaining business is expected to merge into Parent's subsidiary. Item 3 summarizes the Merger Agreement and is incorporated herein by reference. H. Agreement and Plan of Merger, dated as of July 14, 2026, by and among Senti Biosciences Holdings, Inc., Senti Holdings, Inc., Sentio Biosciences, Inc., Celadon Partners SPV 35 Limited and Senti Merger Sub, Inc. (incorporated herein by reference to Exhibit 2.1 to the Issuer's Current Report on Form 8-K filed on July 14, 2026 (File No. 001-40440)). Celadon Partners SPV 24 /s/ John Cullinane 07/16/2026 Celadon Partners, LLC /s/ John Cullinane 07/16/2026 CPIF II-7 Limited /s/ John Cullinane 07/16/2026