When Equity Factors Drop Their Shorts

Abstract

This paper makes a breakdown of common Fama-French style equity factor portfolios into their long and short legs. We find that factor premiums originate in both legs, but that (i) most added value tends to come from the long legs, (ii) the long legs of factors offer more diversification than the short legs, and (iii) the performance of the shorts is generally subsumed by the longs. These results hold across large and small caps, are robust over time, carry over to international equity markets, and cannot be attributed to differences in tail risk. Portfolio tests suggest that the short legs are of limited value to most investors, while the long legs in small caps are most attractive. We also examine recent claims that the value and low-risk factors are subsumed by the new Fama-French factors, and find that this does not hold for the long legs of these factors. Altogether, our findings show that decomposing canonical factors into their long and short legs is crucial for understanding factor premiums and building efficient factor portfolios.