Piotroski isn't your typical Wall Street big shot. In fact, he's not even a professional investor. He's a good old numbers-crunching accountant and college professor. But in 2000, shortly after he started teaching at the University of Chicago's Graduate School of Business, Piotroski published a groundbreaking paper in the Journal of Accounting Research entitled "Value Investing: The Use of Historical Financial Statement Information to Separate Winners from Losers". In it, Piotroski laid out an accounting-based stock-selection/shorting method that produced a 23 percent average annual back-tested return from 1976 through 1996 -- more than double the S&P 500's gain during that time. Piotroski's findings were reported in major financial publiations like SmartMoney. Today, he teaches accounting at Stanford University's Graduate School of Business.
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Since 2004, this portfolio has returned 97.6%, underperforming the market by 75.8% using its optimal annual rebalancing period and 20 stock portfolio size.
Validea used the investment strategy outlined in the paper Value Investing written by Joseph Piotroski to create our Book/Market Investor portfolio.
Piotroski's methodology starts by narrowing stock choices to those trading in the top 20 percent of the market based on their book/market ratios (or, conversely, the bottom 20 percent of the market based on price/book ratios). He found that just buying low price/book stocks does not produce excess returns over the long term, because many low price/book companies are trading at a discount because they deserve to -- they're dogs with poor prospects. When he applied a series of additional tests of financial strength to these low price/book stocks, however, Piotroski was able to separate the dogs from the good prospects. Among the variables he examined: return on assets, current ratio, cash flow from operations, change in gross margin, and change in asset turnover. The strategy usually finds smaller companies whose stocks are flying under Wall Street's radar.
Joseph Piotroski Strategy Description Video
Performance Disclaimer: Returns presented on Validea.com are model returns and do not represent actual trading. As a result, they do not incorporate any commissions or other trading costs or fees. Model portfolios with inception dates on or after 12/30/2005 include a combination of back tested and live model returns. The back-tested performance results shown are hypothetical and are not the result of real-time management of actual accounts. The back-testing of performance differs from actual account performance because the investment strategy may be adjusted at any time, for any reason and can continue to be changed until desired or better performance results are achieved. Back-tested returns are presented to provide general information regarding how the underlying strategy behind the portfolio performed in our historical testing. A back-tested strategy has the benefit of hindsight and the results do not reflect the impact that material economic or market factors may have had on advisor's decision-making if actual client assets were being managed using this approach.
Optimal portfolios presented on Validea.com represent the rebalancing period that has led to the best historical performance for each of our equity models. Each optimal portfolio was determined after the fact with performance information that was not available at portfolio inception. As a result, an investor could not have invested in the
optimal portfolio since its inception. Optimal portfolios are presented to allow investors to quickly determine the portfolio size and rebalancing period that has performed best for each of our models in our historical testing.
Both the model portfolio and benchmark returns presented for all equity portfolios on Validea.com are not inclusive of dividends. Returns for our ETF portfolios and trend following system, and the benchmarks they are compared to, are inclusive of dividends. The S&P 500 is presented as a benchmark because it is the most widely followed benchmark of the overall US market and is most often used by investors for return comparison purposes. As with any investment strategy, there is potential for profit as well as the possibility of loss and investors may incur a loss despite a past history of gains. Past performance does not guarantee future results. Results will vary with economic and market conditions.