Evidence of excessive comovement among stocks following index additions (Barberis, Shleifer, and Wurgler, 2005) and stock splits (Green and Hwang, 2009) challenges traditional finance theory. We show that the bivariate regressions in this literature provide little information about the economic magnitude of excess comovement, with coefficients that are sensitive to unrelated factors. Using robust univariate regressions and matched control samples, almost all evidence of excess comovement disappears. In both examples, the stocks exhibit strong returns prior to the event, akin to momentum winners. We document that winner stocks exhibit increases in betas, generating much of the apparent excess comovement.

We develop a new methodology that controls for both the timing of annual earnings news (Asquith et al., 1989) and the performance prior to split announcements (Barber and Lyon, 1996) to evaluate the information content of stock splits. In contrast to existing evidence, we find that stock splits in aggregate are followed by positive abnormal future earnings growth, suggesting that stock splits contain information about future, rather than past, operating performance. When we use changes in breadth of institutional ownership as a new metric of information content to corroborate our findings, we find that splits with the greatest increase in breadth experience positive post-split abnormal returns and positive abnormal earnings growth. Together, our results suggest that some splits contain positive information about future performance, and that sophisticated market participants such as institutional investors are able to select these splits.

ABSTRACT We study the price effects of changes to the S&P 500 index and document an asymmetric price response: There is a permanent increase in the price of added firms but no permanent decline for deleted firms. These results are at odds with extant explanations of the effects of index changes that imply a symmetric price response to additions and deletions. A possible explanation for asymmetric price effects arises from the changes in investor awareness. Results from our empirical tests support the thesis that changes in investor awareness contribute to the asymmetric price effects of S&P 500 index additions and deletions.

We provide a first look at short selling by mutual funds, a phenomenon not examined by prior research. Mutual funds that short do so frequently and in significant amounts, averaging about 16% of fund assets. These funds outperform benchmarks by 1.5% per year. An analysis of portfolio holdings shows that these funds generate abnormal performance from their short (4.1% per year) and long (1.5% per year) positions. Managers of short-selling mutual funds also exhibit superior performance in other funds they manage that do not use short sales. These findings suggest that managers of short-selling mutual funds are skilled.

We show that hedge fund managers who more actively and astutely adjust the political sensitivity of their portfolios, in line with the dynamic U.S. political landscape, improve their investment performance. Funds that tilt their portfolios toward market segments expected to perform better during the new political regime, specifically around U.S. Presidential elections, generate significantly higher alphas. Further, hedge fund families with greater responsiveness to political changes exhibit persistently superior performance and are more likely to survive. Hedge fund investors reward more responsive fund managers with greater inflows.

Using detailed data on company visits by Chinese mutual funds, we provide direct evidence of mutual fund information acquisition activities and the consequent informational advantages mutual funds establish in local firms. Mutual funds are more likely to visit local and nearby firms both in and outside of their portfolios, but the ease of travel between fund and firm locations can substantially alleviate geographic distance constraints. Company visits by mutual funds are strongly associated with both fund trading activities and fund trading performance. Our results show that geographic constraints and costly information acquisition amplify information asymmetry in financial markets.