Many studies report that the size effect in the cross-section of stock returns disappeared after the early 1980s. This paper shows that its disappearance can be attributed to negative shocks to the profitability of small firms and positive shocks to big firms. After adjusting for the price impact of profitability shocks, we find a robust size effect in the cross-section of expected returns after the early 1980s. Our results highlight the importance of in-sample cash-flow shocks in understanding cross-sectional return predictability.Received April 2, 2014; editorial decision August 6, 2018 by Editor Laura Starks.

We study the dynamics of high-frequency market efficiency measures. We provide evidence that these measures comove across stocks and with each other, suggesting the existence of a systematic market efficiency component. In vector autoregressions, we show that shocks to funding liquidity (the TED spread), hedge fund assets under management, and a proxy for algorithmic trading are significantly associated with systematic market efficiency. Thus, stock market efficiency is prone to systematic fluctuations, and, consistent with recent theories, events and policies that impact funding liquidity can affect the aggregate degree of price efficiency.