If you haven’t heard of Joseph Piotroski, you’re not alone. He’s probably the least well-known of the investment “gurus” who inspired my strategies. Actually, he’s not even a professional investor, but instead an accountant and college professor.
In 2000, however, Piotroski showed that you don’t need to be a smooth-talking Wall Street hot-shot to make it big in the market. While teaching at the University of Chicago, he authored a research paper that showed how assessing stocks with simple accounting-based methods could produce excellent returns over the long haul. No fancy formulas, no insider knowledge — just a straightforward assessment of a company’s balance sheet.
His study turned quite a few heads on Wall Street. It focused on companies that had high book/market ratios — i.e. the type of unpopular stocks whose book values (total assets minus total liabilities) were high compared to the value investors ascribed to them (their share price multiplied by their number of shares).
Quite often, such firms have low book/market ratios because they are in financial distress, and investors wisely stay away from them. On certain occasions, however, high book/market firms may be good companies that are being overlooked by investors for one reason or another. These firms can be great investment opportunities, because their stock prices will likely jump once Wall Street realizes it’s been shunning a winner.
Through his research, Piotroski developed a methodology to separate the solid but overlooked high book/market firms from high book/market ratio firms that were in financial distress. He found that this method, which included a number of balance-sheet-based criteria, increased the return of a high book/market investor’s portfolio by at least 7.5 percent annually. In addition, he found that buying the high book/market firms that passed his strategy and shorting those that didn’t would have produced an impressive 23 percent average annual return from 1976 and 1996.
Since I started tracking it on Validea.com in late February 2004, a 10-stock portfolio picked using my Piotroski-based model has outperformed the market, though with some big ups and downs. Over its first four-and-a-half years or so, it was more than five times ahead of the S&P 500. It was hit hard — like the rest of the market — in 2008, however, falling more than 37%, and it didn’t bounce back much in 2009, gaining just 6.8%. Still, despite the recent struggles, the portfolio is up 16.7% since inception, a period in which the S&P 500 has lost 4.3%.
Let’s take a look at how Piotroski’s approach, and the model I base off of it, work.
Diving into The Balance Sheet
Piotroski wasn’t the first to study high book/market stocks. But his research took things a step further than many past studies. He noted that the majority of high book/market stocks ended up being losers, and that the success of high book/market portfolios was usually dependent on the big gains of a small number of winners. Much as low price/earnings ratio investors like John Neff used a variety of tests to make sure low P/E stocks weren’t rightfully being overlooked because of poor financials, Piotroski sought to separate the high book/market winners from the high book/market losers.
The first step in this approach is, of course, to find high book/market ratio stocks. In his study, Piotroski focused on the stocks whose book/market ratios were in the top 20 percent of the market, so that’s the figure I use.
That’s the easy part. The harder part is determining whether investors are avoiding a low-B/M stock because it is in financial trouble, or whether the company is a solid one that is simply being overlooked. The Piotroski-based model looks at a variety of factors to determine this, including return on assets and cash flow from operations, both of which should be positive.
Several of Piotroski’s other financial criteria don’t necessarily look for fundamental excellence, but instead for improvement. This makes a lot of sense; a company whose return on assets had declined from 10 percent to 1 percent and whose cash flow from operations had dwindled from $10 million to $10,000 would pass the above ROA and cash flow tests, for example, but it certainly wouldn’t be the type of strong performer Piotroski was targeting.
Among the other “change” criteria Piotroski examined were the long-term debt-asset ratio, which he wanted to be declining; the current ratio (current assets/current liabilities), which he wanted to be increasing; gross margin, which should be rising; and asset turnover, which measures productivity by comparing how much sales a company is making in relation to the amount of assets it owns (That should be increasing).