American Association of Individual Investors (AAII) | 2,505 followers on LinkedIn. The American Association of Individual Investors is a nonprofit organization with about 170,000 members whose purpose is to educate individual investors regarding stock market portfolios, financial planning, and retirement accounts. AAII “assists individuals in becoming effective managers of their own assets through programs of education, information and research.” The organization markets itself as an unbiased source of investment information because of its not-for-profit status.