When Equity Factors Drop Their Shorts

Although factor premiums originate in both long and short legs of factor portfolios, we found that (1) most added value comes from the long legs, (2) the long legs offer more diversification than the short legs, and (3) the performance of the short legs is generally subsumed by that of the long legs. These results are robust over size, time, and markets and cannot be attributed to differences in tail risk. We also found that the claim that the value and low-risk factors are subsumed by the new (post-2015) Fama–French factors does not hold for the long legs of these factors.