Stock-market trading is increasingly dominated by sophisticated professionals, as opposed to individual investors. Will this trend ultimately lead to greater market efficiency? I consider two complicating factors. The first is crowding—the fact that, for a wide range of “unanchored” strategies, an arbitrageur cannot know how many of his peers are simultaneously entering the same trade. The second is leverage—when an arbitrageur chooses a privately optimal leverage ratio, he may create a fire-sale externality that raises the likelihood of a severe crash. In some cases, capital regulation may be helpful in dealing with the latter problem.

Stock‐market trading is increasingly dominated by sophisticated professionals, as opposed to individual investors. Will this trend ultimately lead to greater market efficiency? I consider two complicating factors. The first is crowding—the fact that, for a wide range of “unanchored” strategies, an arbitrageur cannot know how many of his peers are simultaneously entering the same trade. The second is leverage—when an arbitrageur chooses a privately optimal leverage ratio, he may create a fire‐sale externality that raises the likelihood of a severe crash. In some cases, capital regulation may be helpful in dealing with the latter problem.

This paper asks how well different organizational structures perform in terms of generating information about investment projects and allocating capital to these projects. A decentralized approach‐with small, single‐manager firms‐is most likely to be attractive when information about projects is “soft” and cannot be credibly transmitted. In contrast, large hierarchies perform better when information can be costlessly “hardened” and passed along inside the firm. The model can be used to think about the consequences of consolidation in the banking industry, particularly the documented tendency for mergers to lead to declines in small‐business lending.

This article examines the role of corporate headquarters in allocating scarce resources to competing projects in an internal capital market. Unlike a bank, headquarters has control rights that enable it to engage in “winner‐picking”—the practice of actively shifting funds from one project to another. By doing a good job in the winner‐picking dimension, headquarters can create value even when it cannot help at all to relax overall firm‐wide credit constraints. The model implies that internal capital markets may sometimes function more efficiently when headquarters oversees a small and focused set of projects.

This article examines the role of corporate headquarters in allocating scarce resources to competing projects in an internal capital market. Unlike a bank, headquarters has control rights that enable it to engage in “winner-picking”—the practice of actively shifting funds from one project to another. By doing a good job in the winner-picking dimension, headquarters can create value even when it cannot help at all to relax overall firm-wide credit constraints. The model implies that internal capital markets may sometimes function more efficiently when headquarters oversees a small and focused set of projects.

This article examines the role of corporate headquarters in allocating scare resources to competing projects in an internal capital market. Unlike a bank, headquarters has control rights that enable it to engage in 'winner-picking'–the practice of actively shifting funds from one project to another. By doing a good job in the winner-picking dimension, headquarters can create value even when it cannot help at all to relax overall firmwide credit constraints. The model implies that internal capital markets may sometimes function more efficiently when headquarters oversees a small and focused set of projects.

We study supply‐and‐demand effects in the U.S. Treasury bill market by comparing the returns on T‐bills to the policy rate on the Federal Reserve's reverse repurchase (RRP) facility. We develop and test a simple model where the RRP‐bill spread is policed both by heterogeneously elastic money funds and by corporate treasurers who derive collateral benefits from holding T‐bills. In response to shifts in T‐bill supply, money funds act as front‐line arbitrageurs. However, when T‐bills become extremely scarce, less elastic corporate treasurers become the marginal investors and supply shifts have a larger effect on T‐bill rates.

We develop a model of monetary policy with two key features: the central bank has private information about its long‐run target rate and is averse to bond market volatility. In this setting, the central bank gradually impounds changes in its target into the policy rate. Such gradualism represents an attempt to not spook the bond market. However, this effort is partially undone in equilibrium, as markets rationally react more to a given move when the central bank moves more gradually. This time‐consistency problem means that society would be better off if the central bank cared less about the bond market.

We model a market populated by two groups of boundedly rational agents: “newswatchers” and “momentum traders.” Each newswatcher observes some private information, but fails to extract other newswatchers' information from prices. If information diffuses gradually across the population, prices underreact in the short run. The underreaction means that the momentum traders can profit by trend‐chasing. However, if they can only implement simple (i.e., univariate) strategies, their attempts at arbitrage must inevitably lead to overreaction at long horizons. In addition to providing a unified account of under‐ and overreactions, the model generates several other distinctive implications.