As filed with the U.S. Securities and Exchange Commission on June 16, 2025. Registration No. 333-287656 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 2 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Pioneer Acquisition I Corp (Exact name of registrant as specified in its charter) Cayman Islands 6770 N/A (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identific ...