On July 31, 2001, for the first time in its history, the New York Stock Exchange (NYSE) began trading three unlisted securities. The DIA, SPY, and QQQ are the most actively traded Exchange Traded Funds (ETFs) and are listed on the American Stock Exchange. On April 15, 2002 another 27 ETFs followed. These two events provide a unique experiment for studying the impact of a new entrant on market quality. In contrast to recently revived concerns about the adverse impact of market fragmentation, we document that the NYSE entry leads to a dramatic improvement in liquidity that we attribute to the elimination of market-maker rents.

In 2001, the Securities and Exchange Commission (SEC) required market centers to publish monthly execution-quality reports in an effort to spur competition for order flow between markets. Using samples of stocks trading on several markets, we investigate whether past execution quality affects order-routing decisions and whether the new disclosure requirements influence this relationship. We find that routing decisions are associated with execution quality; markets reporting low execution costs and fast fills subsequently receive more orders. Moreover, the reports themselves appear to provide information that was unavailable previously. Our results are consistent with active competition for order flow that can be influenced by public disclosure.

We show that stock prices are more accurate when short sellers are more active. First, in a large panel of NYSE-listed stocks, intraday informational efficiency of prices improves with greater shorting flow. Second, at monthly and annual horizons, more shorting flow accelerates the incorporation of public information into prices. Third, greater shorting flow reduces post-earnings-announcement drift for negative earnings surprises. Fourth, short sellers change their trading around extreme return events in a way that aids price discovery and reduces divergence from fundamental values. These results are robust to various econometric specifications, and their magnitude is economically meaningful.

Using a broad panel of NYSE-listed stocks between 1983 and 2004, we study the relation between institutional shareholdings and the relative informational efficiency of prices, measured as deviations from a random walk. Stocks with greater institutional ownership are priced more efficiently, and we show that variation in liquidity does not drive this result. One mechanism through which prices become more efficient is institutional trading activity, even when institutions trade passively. But efficiency is also directly related to institutional holdings, even after controlling for institutional trading, analyst coverage, short selling, variation in liquidity, and firm characteristics. (JEL G12, G14) Institutional shareholdings and trading have increased dramatically over the past several decades. In 1965, members of the Securities Industries Association held 16 % of U.S. equities; in 2001, they held 61 % according to the Securities Industry Association Fact Book (2002). Moreover, nonretail trading accounted for 96 % of New York Stock Exchange (NYSE) trading volume in 2002 (Jones and Lipson 2004). How this broadened scope of institutional ownership and trading affects the quality of equity markets, however, is an open question.

In this paper, we present a case study of underwriter trading in the aftermarket of a recent initial public offering (IPO). The lead underwriter for this issue actively repurchased approximately 15% of the issue size to cover its initial short position. Detailed audit-trail and short-covering data identify the timing, volume, and counterparties for the Lead's trades. We find that price-support objectives are important on the first two short-covering days. Subsequently, repurchases appear to be governed primarily by their profitability and market liquidity. The Lead incurs lower transaction costs than other large traders, but provides substantial liquidity to the market.

We examine product differentiation in the high-frequency trading (HFT) industry, where the “products” are secretive proprietary trading strategies. We demonstrate how principal component analysis can be used to detect underlying strategies common to multiple HFT firms and show that there are three product categories with distinct attributes. We study how HFT competition in each product category affects the market environment and present evidence that indicates how it influences the short-horizon volatility of stocks as well as the viability of trading venues. Received October 10, 2016; editorial decision September 30, 2017 by Editor Itay Goldstein.

This paper presents our investigation of the factors that determine secondary market prices of developing country syndicated loans. Trading volume in this market has almost doubled yearly from 1985 to 1988 while average market prices declined from 73% to 41% of par value during the same period. We find that loan values depend on a country's solvency rather than its liquidity and show that a country's adoption of a debt conversion program significantly decreases its loans' market prices. Furthermore, the debt moratoria by Brazil and Peru, as well as the developing-country-specific provisions made by U.S. banks, impact loan prices negatively.

Short sellers are known to have private information about security prices. Empirical evidence of short selling, however, is based on only half of short sellers’ trading activity; specifically, the opening of the position. Using disclosed large-short-position data from the Japanese stock market, we provide the first detailed evidence of covering trades and find a positive reaction to short covering that only partially reverses. Although these results are consistent with substantial transaction costs for closing large short positions, they also reveal that some short sellers are privately informed about positive future events and have timing ability in covering positions.

We study the effect of algorithmic trading (AT) on market quality between 2001 and 2011 in 42 equity markets around the world. We use an exchange colocation service that increases AT as an exogenous instrument to draw causal inferences about AT on market quality. On average, AT improves liquidity and informational efficiency but increases short-term volatility. Importantly, AT also lowers execution shortfalls for buy-side institutional investors. Our results are surprisingly consistent across markets and thus across a wide range of AT environments. We further document that the beneficial effect of AT is stronger in large stocks than in small stocks.