As filed with the U.S. Securities and Exchange Commission on January 26, 2026 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ClearThink 1 Acquisition Corp. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Cayman Islands 6770 N/A (Primary Standard Industrial Classification Code Number) William Brock Chief Executive Officer ClearTh ...