UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 12, 2026 Fulcrum Therapeutics, Inc. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation) Delaware 001-38978 47-4839948 (Commission File Number) (IRS Employer Identification No.) 26 Landsdowne Street Cambridge, Massachusetts 02139 (Address ...