Wayne Thorp (CFA) from the American Association of Individual Investors explains about the use of stock screeners and the AAII Micro Cap Portfolio. This portfolio is based on the research from Eugene Fama and Kenneth French that showed that stocks with both low market capitalisations and low price to book market ratios on average outperformed the markets. Over the long run (since 1992) the Micro Cap portfolio outperformed the markets by around 4% annually. Thorpe explains in detail the screener criteria. Examples of these criteria are a minimum stock price of 4 USD and positive earnings over the past 12 months. Financials are excluded for this Micro Cap Portfolio.