X0202 SCHEDULE 13D/A 0000902664-26-003126 0002060465 XXXXXXXX LIVE 6 Common Stock, par value $0.0001 per share 09/03/2026 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 Common Stock assuming the issuance of the Initial Notes (as defined in Item 3 of the Schedule 13D) takes place on the date hereof, 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 assuming the issuance of the Initial Notes (as defined in Item 3 of the Schedule 13D) takes place on the date hereof, 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 assuming the issuance of the Initial Notes (as defined in Item 3 of the Schedule 13D) takes place on the date hereof, 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. 6 ("Amendment No. 6") to the Schedule 13D filed with the U.S. Securities and Exchange Commission (the "SEC") on March 13, 2025 (as amended, the "Schedule 13D"). This Amendment No. 6 supplements Items 3 and 4 and amends and restates Item 5(a)-(c) as set forth below. Capitalized terms used herein and not otherwise defined in this Amendment No. 6 have the meanings set forth in the Schedule 13D. On September 3, 2026, the Issuer entered into an equity commitment letter (the "Equity Commitment Letter") with CPIF II-9 Limited (the "Investor"), an entity affiliated with Celadon Partners SPV 24. Pursuant to the Equity Commitment Letter, the Investor commits to purchase, or to cause one or more of its affiliates to purchase, newly issued shares of Common Stock, for an aggregate purchase price equal to $2,500,000 (the "Commitment"; such amount, the "Commitment Amount"), at a per share price equal to the "Minimum Price" as defined in Nasdaq Listing Rule 5635(d) (the "Per Share Price"). The number of shares to be purchased shall equal the Commitment Amount divided by the Per Share Price (rounded down to the nearest whole share). The Investor's obligation to satisfy the Commitment is subject to (a) the substantially contemporaneous consummation of the Closing (as defined in the Merger Agreement), (b) the Issuer having submitted to the Listing Qualifications Department of the Nasdaq Stock Market LLC ("Nasdaq") a letter and compliance plan demonstrating the Issuer's ability to satisfy the minimum stockholders' equity requirement for continued listing on the Nasdaq Capital Market following the consummation of the Closing and the other transactions contemplated by the Merger Agreement (the "Nasdaq Compliance Plan"), provided that the Issuer shall provide the Investor with a reasonable ability to review and comment on the Nasdaq Compliance Plan and shall consider any comments by the Investor in good faith prior to submission of the Nasdaq Compliance Plan, (c) the Issuer retaining at least $600,000 in existing cash or cash equivalents following completion of the Closing, (d) the Issuer having taken commercially reasonable steps to maintain the listing of the Common Stock on the Nasdaq Capital Market through and following the Closing, and (e) the execution and delivery, at or prior to the Closing, of a registration rights agreement providing the Investor (or its applicable affiliate) with customary demand and piggyback registration rights with respect to the Common Stock purchased pursuant to the Equity Commitment Letter. The Issuer plans to use substantially all of the proceeds from the sale of shares of Common Stock pursuant to the Equity Commitment Letter to support its business following completion of the Merger. See rows (11) and (13) of the cover page to this Schedule 13D for the aggregate number of shares of Common Stock and percentage of shares of Common Stock beneficially owned by each Reporting Person. The aggregate percentage of shares of Common Stock reported beneficially owned by each Reporting Person is based upon 47,116,644 shares of Common Stock that would be issued and outstanding as determined by (i) 31,144,754 shares of Common Stock issued and outstanding as of July 31, 2026, as disclosed in the Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, filed by the Issuer with the SEC on August 14, 2026 and (ii) assuming the issuance of the Initial Notes (as defined in Item 3 of the Schedule 13D) takes place on the date hereof, the requisite stockholder approval of the Issuer's stockholders is obtained, and the immediate exchange of such Initial Notes for 15,971,890 shares of Common Stock pursuant to the Securities Purchase Agreement (as defined in Item 3 of the Schedule 13D). See rows (7) through (10) of the cover page to this Schedule 13D for the shares of Common Stock as to which the Reporting Persons have the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition. See Items 3 and 4. Item 3 summarizes the Equity Commitment Letter and the Note and is incorporated herein by reference. I. Equity Commitment Letter, dated September 3, 2026, by and among Senti Biosciences Holdings, Inc. and the investor named therein (incorporated herein by reference to Exhibit 10.2 to the Issuer's Current Report on Form 8-K filed on September 4, 2026 (File No. 001-40440)). Celadon Partners SPV 24 /s/ John Cullinane 09/11/2026 Celadon Partners, LLC /s/ John Cullinane 09/11/2026 CPIF II-7 Limited /s/ John Cullinane 09/11/2026