As filed with the U.S. Securities and Exchange Commission on November 28, 2025 Registration No. 333-291347 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Abpro Holdings, Inc. (Exact Name of Registrant as Specified in its Charter) (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) Delaware 2834 87-1013956 (I.R.S. Employer Identificat ...

Core Insights - Abpro Holdings, Inc. has implemented a 1-for-30 reverse stock split to maintain compliance with Nasdaq and position the company for future growth [1][4] - The company has achieved approximately 60% reduction in operating costs compared to the same period in 2024 through a focused cost optimization plan [1][4] - Abpro's partnership with Celltrion is a strategic advantage, as Celltrion funds all development expenses for Abpro's lead antibody program ABP-102, with a first-in-human trial anticipated in 2026 [5][4] Company Actions - The reverse stock split became effective on October 31, 2025, reducing the number of outstanding shares from approximately 81.2 million to 2.7 million [2] - The company's transfer agent, Continental Stock Transfer & Trust Company, will act as the exchange agent for the reverse stock split [3] Strategic Positioning - Abpro is focused on unlocking additional value through its DiversImmune® and MultiMabTM platforms, which facilitate the rapid creation of bispecific and multispecific antibodies [6] - The company aims to create long-term value for shareholders by executing more effectively with a leaner cost structure and a major global partner [4] Company Overview - Abpro is dedicated to improving lives through next-generation antibody therapies targeting severe diseases, utilizing its proprietary DiversImmune® platform [7]