We examine whether the post-earnings announcement drift (PEAD) varies cross-sectionally with short-horizon return predictability from order flows, which characterizes the information environment and reflects the extent to which information is efficiently impounded in prices. We first demonstrate that this proxy for market efficiency (developed by Chordia, Roll, and Subrahmanyam 2008) captures the degree of market frictions that limit arbitrage activities. We then present evidence that the inverse of short-horizon return predictability is negatively associated with the PEAD and remains statistically and economically significant after controlling for a wide range of explanatory variables used in prior research. Finally, although we find that profits of implementing the PEAD trading strategy are significantly reduced by transaction costs, we demonstrate that profits continue to remain statistically and economically significant for the less efficient firms that face otherwise higher barriers to arbitrage. Our results indicate that short-horizon return predictability from order flows better explains stock returns after earnings announcements.

Chordia et al. (2008, hereafter CRS) examine short horizon return predictability from past order flows of large, actively traded NYSE firms across three tick size regimes and conclude that higher liquidity facilitates arbitrage trading which enhances market efficiency. We extend CRS to a comprehensive sample of all NYSE firms and examine the dynamics between liquidity and market efficiency during informational periods. Our results indicate that although all NYSE firms experience an overall improvement in market efficiency across periods of different tick size regimes, this improvement varies significantly across the portfolios of sample companies formed on the basis of trading frequency, market capitalization, and trading volume. After controlling for these factors, we further document a positive association between a continuous measure of liquidity and market efficiency, and show that this effect is amplified during periods that contain new information, as reflected in high adverse selection component of the bid-ask spread.

We revisit the stock market anomaly documented by Thomas and Zhang (2008) and show that the apparent mispricing of information transfers has decayed over time, as the US markets experienced rapid improvements in the efficiency of the underlying price formation processes. Utilizing recent advancements in market microstructure research to estimate firm-specific proxies for market efficiency, we demonstrate that the existence of the overreaction anomaly (where stock prices of late announcers in response to the earnings reported by early announcers in the same industry are negatively related to subsequent price responses of late announcers to their own earnings reports) is specific to an earlier sample period and results from the inefficient incorporation of information into prices, largely attributable to an environment with high barriers to arbitrage. Our results indicate that the pricing efficiency of intra-industry information transfers has increased in the recent years of increased liquidity and markedly higher trading activity.