Selecting the PortfoliosPast Returns StrategyEach year, after ranking stocks by their return over the last one year, a trading strategy that buys the top 30% of stocks and finances this position by short selling bottom 30% of stocks has historically produced positive risk-adjusted returns. This self-financing portfolio is widely known as the prior one-year momentum (PR1YR) portfolio. This trading strategy requires holding the portfolio for a year, and the process is repeated annually.