նTRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACTOF 1934 For the transition period fromtoCommission file number: 001-38443 Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.YesշNoն Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.YesնNoշ Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 duringthe preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for thepast 90 days.YesշNoն Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 ofRegulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).YesշNoն Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or anemerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule12b-2 of the Exchange Act. Large accelerated filerշNon-accelerated filerնEmerging growth companyն Smaller reporting companyն If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new orrevised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.ն Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal controlover financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its auditreport.շ If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filingreflect the correction of an error to previously issued financial statements.ն Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received byany of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).ն Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).YesնNoշ The aggregate market value of Common Stock held by non-affiliates of the registrant computed by reference to the price of the registrant’s Common Stock asof June 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, was approximately $772.9 million (based on the last reportedsale price on the Nasdaq Global Select Market as of such date). DOCUMENTS INCORPORATED BY REFERENCE The information required by Part III of this report, to the extent not set forth herein, is incorporated herein by reference from our definitive proxy statement relating tothe 2026 Annual Meeting of Stockholders, which definitive proxy statement shall be filed with the Securities and Exchange Commission within 120 days after the endof the annual period to which this report relates. Cogent Biosciences, Inc.Index PART I Item 1.BusinessItem 1A.Risk FactorsItem 1B.Unresolved Staff CommentsItem 1C.CybersecurityItem 2.PropertiesItem 3.Legal ProceedingsItem 4.Mine Safety Disclosures PART II Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchasesof Equity Securities66Item 6.[Reserved]67Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations68Item 7A.Quantitative and Qualitative Disclosures About Market Risk81Item 8.Financial Statements and Supplementary Data82Item 9.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure113Item 9A.Controls and Procedures113Item 9B.Other Information114Item 9C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections114 PART III Item 10.Directors, Executive Officers and Corporate Governance115Item 11.Executive Compensation115Item 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters115Item 13.Certain Relationships and Related Transactions, and Director Independence115Item 14.Principal Accounting Fees and Services115 PART IV Item 15.Exhibits, Financial Statement Schedules116Item 16.Form 10-K Summary119EXHIBITS INDEX116SIGNATURES120 Summary of the Material Risks Associated with Our Business Our business is subject to numerous risks and uncertainties that you should be aware of in evaluating our business.These ri