We study market efficiency in an infinite-horizon model with a monopolistic insider. The insider can trade with a competitive market maker 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. The insider chooses, however, to reveal the 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 model asset management as a continuum between active and passive: managers can deviate from benchmark indices to exploit noise trader–induced distortions, but agency frictions constrain these deviations. Because constraints force managers to buy assets that they underweight when these assets appreciate, overvalued assets have high volatility, and the risk-return relationship becomes inverted. Distortions are more severe for overvalued assets than for undervalued ones because trading against the former entails more risk and tighter constraints. We provide empirical evidence supporting our model’s main mechanisms. Using the data, we infer the constraints’ tightness and compute a measure of effective arbitrage capital.

We develop a model in which financially constrained arbitrageurs exploit price discrepancies across segmented markets. We show that the dynamics of arbitrage capital are self‐correcting: following a shock that depletes capital, returns increase, which allows capital to be gradually replenished. Spreads increase more for trades with volatile fundamentals or more time to convergence. Arbitrageurs cut their positions more in those trades, except when volatility concerns the hedgeable component. Financial constraints yield a positive cross‐sectional relationship between spreads/returns and betas with respect to arbitrage capital. Diversification of arbitrageurs across markets induces contagion, but generally lowers arbitrageurs' risk and price volatility.

We propose a model in which assets with identical cash flows can trade at different prices. Infinitely lived agents can establish long positions in a search spot market, or short positions by first borrowing an asset in a search repo market. We show that short‐sellers can endogenously concentrate in one asset because of search externalities and the constraint that they must deliver the asset they borrowed. That asset enjoys greater liquidity, a higher lending fee (“specialness”), and trades at a premium consistent with no‐arbitrage. We derive closed‐form solutions for small frictions, and provide a calibration generating realistic on‐the‐run premia.

We develop a two-country model in which currency and bond markets are populated by different investor clienteles, and segmentation is partly overcome by arbitrageurs with limited capital. Risk premia in our model are time-varying, connected across markets, and consistent with the empirical violations of uncovered interest parity and expectations hypothesis. Through risk premia, large-scale bond purchases lower domestic and foreign bond yields and depreciate the currency, and short-rate cuts lower foreign yields, with smaller effects than bond purchases. Currency returns are disconnected from long-maturity bond returns, and yet the currency market is instrumental in transmitting bond demand shocks across countries.

We study how passive investing affects asset prices. Flows into passive funds disproportionately raise the stock prices of the economy’s largest firms, especially those large firms in high demand by noise traders. Because of this effect, the aggregate market can rise even when flows are entirely due to investors switching from active to passive funds. Intuitively, passive flows increase the idiosyncratic risk of large firms in high demand, which discourages investors from correcting the flows’ effects on prices. Consistent with our theory, prices and idiosyncratic volatilities of the largest S&P500 firms rise the most following flows into that index.

We propose a simple model of the sovereign-bank diabolic loop, and establish four results. First, the diabolic loop can be avoided by restricting banks' domestic sovereign exposures relative to their equity. Second, equity requirements can be lowered if banks only hold senior domestic sovereign debt. Third, such requirements shrink even further if banks only hold the senior tranche of an internationally diversified sovereign portfolio--known as ESBies in the euro-area context. Finally, ESBies generate more safe assets than domestic debt tranching alone; and, insofar as the diabolic loop is defused, the junior tranche generated by the securitization is itself risk-free.