[In this article we study the effects of transaction costs on asset prices. We assume an overlapping generations economy with a riskless, liquid bond, and many risky stocks carrying proportional transaction costs. We obtain stock prices and turnover in closed form. Surprisingly, a stock's price may increase in transaction costs, and a more frequently traded stock may be less adversely affected by an increase in transaction costs. Calculations based on the "marginal" investor overestimate the effects of transaction costs. For realistic parameter values, transaction costs have very small effects on stock prices but large effects on turnover.]

We examine empirically how the supply and maturity structure of government debt affect bond yields and expected returns. We organize our investigation around a term-structure model in which risk-averse arbitrageurs absorb shocks to the demand and supply for bonds of different maturities. These shocks affect the term structure because they alter the price of duration risk. Consistent with the model, we find that the maturity-weighted-debt-to-GDP ratio is positively related to bond yields and future returns, controlling for the short rate. Moreover, these effects are stronger for longer-maturity bonds and following periods when arbitrageurs have lost money.

[We propose a theory of momentum and reversal based on flows between investment funds. Flows are triggered by changes in fund managers' efficiency, which investors either observe directly or infer from past performance. Momentum arises if flows exhibit inertia, and because rational prices underreact to expected future flows. Reversal arises because flows push prices away from fundamental values. Besides momentum and reversal, flows generate comovement, lead-lag effects, and amplification, with these being larger for high idiosyncratic risk assets. A calibration of our model using evidence on mutual fund returns and flows generates sizeable Sharpe ratios for momentum and value strategies.]

[We analyze how asymmetric information and imperfect competition affect liquidity and asset prices. Our model has three periods: Agents are identical in the first, become heterogeneous and trade in the second, and consume asset payoffs in the third. We show that asymmetric information in the second period raises ex ante expected asset returns in the first, comparing both to the case where all private signals are made public and to that where private signals are not observed. Imperfect competition can instead lower expected returns. Each imperfection can move common measures of illiquidity in opposite directions.]

[We study market efficiency in an infinite-horizon model with a monopolistic insider. The insider can trade with competitive market makers and noise traders, and observes privately the expected growth rate of asset dividends. In the absence of the insider, this information would be reflected in prices only after a long series of dividend observations. Thus, the insider's information is "long-lived." Surprisingly, however, the monopolistic insider chooses to reveal her information very quickly, within a time converging to zero as the market approaches continuous trading. Although the market converges to strong-form efficiency, the insider's profits do not converge to zero.]

[We propose a clientele-based model of the yield curve and optimal maturity structure of government debt. Clienteles are generations of agents at different lifecycle stages in an overlapping-generations economy. An optimal maturity structure exists in the absence of distortionary taxes and induces efficient intergenerational risksharing. If agents are more risk-averse than log, then an increase in the long-horizon clientele raises the price and optimal supply of long-term bonds—effects that we also confirm empirically in a panel of OECD countries. Moreover, under the optimal maturity structure, catering to clienteles is limited and long-term bonds earn negative expected excess returns.]

In this article we study the effects of transaction costs on asset prices. We assume an overlapping generations economy with a riskless, liquid bond, and many risky stocks carrying proportional transaction costs. We obtain stock prices and turnover in closed form. Surprisingly, a stock's price may increase in transaction costs, and a more frequently traded stock may be less adversely affected by an increase in transaction costs. Calculations based on the “marginal” investor overestimate the effects of transaction costs. For realistic parameter values, transaction costs have very small effects on stock prices but large effects on turnover.

We examine empirically how the supply and maturity structure of government debt affect bond yields and expected returns. We organize our investigation around a term-structure model in which risk-averse arbitrageurs absorb shocks to the demand and supply for bonds of different maturities. These shocks affect the term structure because they alter the price of duration risk. Consistent with the model, we find that the maturity-weighted-debt-to-GDP ratio is positively related to bond yields and future returns, controlling for the short rate. Moreover, these effects are stronger for longer-maturity bonds and following periods when arbitrageurs have lost money.

We propose a theory of momentum and reversal based on flows between investment funds. Flows are triggered by changes in fund managers' efficiency, which investors either observe directly or infer from past performance. Momentum arises if flows exhibit inertia, and because rational prices underreact to expected future flows. Reversal arises because flows push prices away from fundamental values. Besides momentum and reversal, flows generate comovement, lead-lag effects, and amplification, with these being larger for high idiosyncratic risk assets. A calibration of our model using evidence on mutual fund returns and flows generates sizeable Sharpe ratios for momentum and value strategies.

We propose a clientele-based model of the yield curve and optimal maturity structure of government debt. Clienteles are generations of agents at different lifecycle stages in an overlapping-generations economy. An optimal maturity structure exists in the absence of distortionary taxes and induces efficient intergenerational risksharing. If agents are more risk-averse than log, then an increase in the long-horizon clientele raises the price and optimal supply of long-term bonds—effects that we also confirm empirically in a panel of OECD countries. Moreover, under the optimal maturity structure, catering to clienteles is limited and long-term bonds earn negative expected excess returns.