One of the most-cited value investing studies says stocks with low price-to-book ratios outperform stocks with high price-to-book ratios. Investment firm GMO’s Ben Inker says the study’s findings still hold, but work better when a one-year lag is used.
In “The Cross-Section of Expected Stock Returns” (The Journal of Finance, June 1992), Eugene Fama and Kenneth French published data showing an inverse relationship between returns and valuations. Average monthly returns ranged from 0.30% for the decile composed of stocks with the highest price-to-book (P/B) ratios to 1.83% for the decile composed of the lowest P/B ratio stocks. Fama and French calculated average returns for the period of July 1963 through December 1990 for their study.
Inker updated the data and shared his findings in the February 2014 GMO Quarterly Letter. He concluded: “If we just look at traditional value for stock selection—good old price/book as enshrined by Fama and French—the cheapest 10% of the market has outperformed the broad market by 2.5% per year since 1965. Sounds fine, but since the original Fama/French paper was published in 1992, the group has actually underperformed by 1.6% per year. The same group lagged one year outperformed by 3.5% per year since 1965, and since 1992 has outperformed by 2% per year. You can see similar patterns in sectors as well. In most cases lagged value either works better than portfolios based on current data or works almost as well.”
What Inker is referring to is buying the stocks whose P/B ratios ranked in the bottom decile one year ago (stocks whose valuations were lower than 90% of all other stocks last year), instead of buying those stocks that now appear in the bottom decile. His rationale for doing so is based on momentum. A stock becomes very cheap because of selling pressure (downward momentum), and the selling pressure may continue for a while. By using lagged valuation data, an investor allows time for the downward momentum to end.