The American Association of Individual Investors is a nonprofit organization with about 150,000 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.

The organization was founded in 1978 by James Cloonan, Ph.D. Over the last thirty years, AAII's members report "investment returns that are consistently higher than those of the stock market as a whole" (using the S&P 500 as reference). Since 2003, AAII has maintained two real portfolios—a shadow stock portfolio and a mutual fund portfolio – for education purposes. These portfolios' returns and contents are available online and, the site reports, have outperformed the market considerably over the course of their existence.