Oklo Inc-A美国存托股招股说明书(2025-04-22版)

This prospectus supplement updates, amends and supplements the prospectus dated September 18, 2024 (the “Prospectus”), which This prospectus supplement is not complete without the Prospectus. This prospectus supplement should be read in conjunction withthe Prospectus, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extent that Oklo Inc.’s Class A Common Stock is quoted on the New York Stock Exchange under the symbol “OKLO.” On April 22, 2025, the WE ARE AN “EMERGING GROWTH COMPANY” UNDER FEDERAL SECURITIES LAWS AND ARE SUBJECT TOREDUCED PUBLIC REPORTING REQUIREMENTS. INVESTING IN OUR SECURITIES INVOLVES CERTAIN RISKS. SEE“RISK FACTORS” BEGINNING ON PAGE 14 OF THE PROSPECTUS. The date of this prospectus supplement is April 22, 2025. Washington, D.C. 20549FORM8-K PURSUANT TO SECTION13 OR 15(d)OF THE SECURITIES EXCHANGE ACT OF 1934 ¨Pre-commencement communications pursuant to Rule13e-4(c)under the Exchange Act (17 CFR 240.13e-4(c)) Emerging growth companyxIf an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for as Chair and as a Class II director of the Board, including as a member of the Board’s Nominating and Corporate GovernanceCommittee, effective April 22, 2025. Mr. Altman’s decision to resign was not due to any disagreement with the Company on any