X0202 SCHEDULE 13D/A 0001937147-24-000001 0001937147 XXXXXXXX LIVE 1 Common Stock, par value $0.001 per share 04/02/2026 false 0001527599 87166L209 SYNLOGIC, INC.

PO BOX 30 WINCHESTER MA 01890

JACOB MA-WEAVER 415-857-1965 CABLE CAR CAPITAL, LP 601 California Street, Suite 1151 San Francisco CA 94108 ANDREW FREEDMAN, ESQ. 212-451-2300 OLSHAN FROME WOLOSKY LLP 1325 Avenue of the Americas New York NY 10019 0001937147 N Funicular Funds, LP WC N DE 3312219.00 0.00 3312219.00 0.00 3312219.00 N 28.3 PN 0001699575 N Cable Car Capital, LP AF N DE 3312219.00 0.00 3312219.00 0.00 3312219.00 N 28.3 IA PN Formerly known as Cable Car Capital LLC 0001922140 N Ma-Weaver Jacob OO N X1 3312219.00 0.00 3312219.00 0.00 3312219.00 N 28.3 IN Common Stock, par value $0.001 per share SYNLOGIC, INC. PO BOX 30 WINCHESTER MA 01890 The following constitutes Amendment No. 1 to the Schedule 13D filed by the undersigned ("Amendment No. 1") relating to the Common Stock, par value $0.001 per share (the "Shares"), of Synlogic, Inc. (the "Issuer"). This Amendment No. 1 amends the Schedule 13D filed by the Reporting Persons as specifically set forth herein. Capitalized terms used but not otherwise defined herein have the meanings ascribed to such terms in the Schedule 13D. Item 2(b) is hereby amended to read as follows: Cable Car is an SEC registered investment adviser and serves as the general partner of the Fund. Item 4 is hereby amended to add the following: On April 2, 2026, the Reporting Persons delivered a letter to the Board of Directors of the Issuer setting forth a non-binding proposal (the "Proposal") to acquire all outstanding Shares not already owned by the Reporting Persons for $0.64 per share in cash. The foregoing description of the Proposal does not purport to be complete and is qualified in its entirety by reference to the Proposal, which is attached as Exhibit 99.1 hereto and is incorporated by reference herein. Item 5(a) is hereby amended and restated to read as follows: The aggregate percentage of Shares reported owned by the Reporting Persons is based on 11,698,919 Shares outstanding as of March 5, 2026, which is the total number of Shares outstanding as reported in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 12, 2026. As of the date hereof, the Fund beneficially owned 3,312,219 Shares, constituting approximately 28.3% of the Issuer's outstanding Shares. Cable Car, as the General Partner of the Fund, may be deemed the beneficial owner of the 3,312,219 Shares owned by the Fund. Mr. Ma-Weaver, as the Managing Member of Cable Car, may be deemed the beneficial owner of the 3,312,219 Shares owned by the Fund. Item 6 is hereby amended to add the following: On April 2, 2026, the Reporting Persons submitted the Proposal defined and described in Item 4 above and attached as Exhibit 99.1 hereto. Item 7 is hereby amended to add the following exhibit: 99.1 - Proposal, dated April 2, 2026. Funicular Funds, LP /s/ Jacob Ma-Weaver 04/06/2026 Cable Car Capital, LP /s/ Jacob Ma-Weaver 04/06/2026 Ma-Weaver Jacob /s/ Jacob Ma-Weaver 04/06/2026