Form S-4 A form that required for submission to SEC when two companies are involved in a merger or acquisition. Home Resources Startup Law Dictionary Form S-4 Return to Glossary Need legal help? Schedule a free consultation with a world-class startup attorney on LawTrades. LET'S CHAT Roy G. Business Attorney Heather N. Business Attorney Jared S. Business Attorney Tell us about your project We'll connect you with a vetted attorney in just a few minutes. Trusted by top companies like :