This paper considers the Arbitrage Pricing Theory when investors have incomplete information on the parameters generating asset returns. Each asset in the economy may have a different amount of information available on it. Bayesian investors use their prior beliefs in conjunction with the total available information to assign an expected return and a set of factor betas to each asset. The assigned expected returns are shown to be linear in their associated factor betas. However, the factor betas and prices of assets differ from those under complete information. Specifically, risky assets with high (low) information are priced relatively higher (lower). On the other hand, factor betas of high (low) information assets are relatively lower (higher). The analysis has econometric implications for testing the APT. In this paper's framework, maximum likelihood estimates of factor betas, which are based on normality assumptions, are too high (low) for high (low) information assets. In addition, sequentially increasing the sample size by adding new securities to a factor analysis procedure can result in the detection of apparent additional priced factors when they do not really exist.

This paper develops an equilibrium factor pricing theory when investors have heterogeneous beliefs about asset payoffs generated by the Ross linear factor model. Investors receive private information about the unknown parameters of the payoff process. They use this private information and equilibrium prices to predict asset payoffs. The paper develops a closed form price function for a noisy rational expectations equilibrium and relates it to the general solution. Even though we allow for a large number of investors, diversity of beliefs and parameter uncertainty both persist in equilibrium. We show that investors' beliefs about expected payoffs are approximately linear in the asset's betas, thus establishing the APT. As investors prefer to hold high information assets in equilibrium, the relative weight of these assets in the APT pricing bound is higher. The reverse is true for low information assets.

We investigate how ownership structure influences operating performance and implied agency costs. Our sample includes over 42,000 U.K. private and public firms. We document several new results of considerable economic significance relating to i) horizontal agency costs arising from unequal ownership within private firms, ii) amplification of agency costs from joint presence within the same firm of horizontal agency problems and vertical agency problems arising from separation of ownership and control, iii) mitigation in agency costs wrought by a second large shareholder, iv) impact of complex ownership structures, and v) agency cost differences between public firms and comparable private firms.

We study the dynamics of cash-and-carry arbitrage using the U.S. crude oil market. Sizable arbitrage-related inventory movements occur at the New York Mercantile Exchange (NYMEX) futures contract delivery point but not at other storage locations, where instead, operational factors explain most inventory changes. We add to the theory-of-storage literature by introducing two new features. First, due to arbitrageurs contracting ahead, inventories respond to not only contemporaneous but also lagged futures spreads. Second, storage-capacity limits can impede cash-and-carry arbitrage, leading to the persistence of unexploited arbitrage opportunities. Our findings suggest that arbitrage-induced inventory movements are, on average, price stabilizing.