We find that a small set of financial columnists has a causal effect on short-term aggregate stock market prices. For some journalists ("bulls") the market reaction is consistently positive, whereas for others ("bears") it is negative. Because bulls and bears are rotated exogenously in our...

Using individual patient records for every hospital in California from 1983-2011, we find a strong inverse link between daily stock returns and hospital admissions, particularly for psychological conditions such as anxiety, panic disorder, or major depression. The effect is nearly instantaneous...

We examine the role of high-frequency traders (HFTs) in price discovery and price efficiency. Overall HFTs facilitate price efficiency by trading in the direction of permanent price changes and in the opposite direction of transitory pricing errors, both on average and on the highest volatility...

We examine empirically the role of high-frequency traders (HFTs) in price discovery and price efficiency. Based on our methodology, we find overall that HFTs facilitate price efficiency by trading in the direction of permanent price changes and in the opposite direction of transitory pricing...

This paper examines whether shareholder litigation contributes to the decline in U.S. stock market listings. We find that higher litigation risk induces firms to delist. We establish causality by exploiting a 1999 decision by the Ninth Circuit Court that reduced litigation risk. The effect is at...

We develop a return variance decomposition model to separate the role of different types of information and noise in stock price movements. We disentangle four components: market-wide information, private firm-specific information revealed through trading, firm-specific information revealed...

We study performance and competition among high-frequency traders (HFTs). We construct measures of latency and find that differences in relative latency account for large differences in HFTs' trading performance. HFTs that improve their latency rank due to colocation upgrades see improved...