Which Factors?

Abstract

Many recently proposed, seemingly different factor models are closely related. In spanning tests, the q-factor model largely subsumes the Fama-French (2015, 2018) 5-and 6-factor models, and the q5 model captures the Stambaugh-Yuan (2017) model. The Stambaugh-Yuan factors are sensitive to their construction, and once replicated via the standard approach, are close to the q-factors, with correlations of 0.8 and 0.84. Finally, it seems difficult to motivate the Fama-French 5-factor model from valuation theory, which predicts a positive relation between the expected investment and the expected return.