The purpose of the Small Business Investment Act of 2025 is to encourage investment in small businesses by modifying tax rules related to the sale of qualified small business stock. This aims to stimulate economic growth and support entrepreneurs by making it more financially attractive for investors to invest in small businesses. Key provisions of the Act include a phased increase in the tax exclusion for gains from selling qualified small business stock. Currently, investors can exclude 50 percent of their gains from taxes if they hold the stock for more than five years.