Small Business Investor Alliance | 6,043 followers on LinkedIn. The Voice of Private Equity | The Small Business Investor Alliance is the association of senior investment professionals focused on the lower middle market whose members represent the entire private capital ecosystem. It is an alliance for professional fellowship, business opportunities, innovation, regulatory expertise, and market data. Established in 1958, SBIA has been playing a pivotal role in promoting the growth and vitality of the private equity industry for more than 60 years.