This paper considers extensions of 2-dimensional factor models to higher-dimension data that can be represented as tensors. I describe decompositions of tensors that generalize the standard matrix singular value decomposition and principal component analysis to higher dimensions. I estimate the...

This paper proposes a new approach to the "factor zoo" conundrum. Instead of applying dimension-reduction methods to a large set of portfolios obtained from sorts on characteristics, I construct factors that summarize the information in characteristics across assets and then sort assets into...

This paper reviews the literature on idiosyncratic equity volatility since the publication of "Have Individual Stocks Become More Volatile? An Empirical Exploration of Idiosyncratic Risk" in 2001. We respond to replication studies by Chiah, Gharghori, and Zhong and by Leippold and Svaton, and we...