We study the use of firms' book-to-market ratios (B/M) in value investing and its implications for comovements in firms’ stock returns and trading volumes. We show B/M has become increasingly detached from common alternative valuation ratios over time while also becoming worse at forecasting...

Using a novel dataset, we show that components of firms' GAAP earnings stemming from ancillary business activities or transitory shocks are significant in frequency and magnitude. These components have grown over time and are dispersed across various sections of the 10-K. Excluding them from...