Information and Heterogeneous Beliefs: Cost of Capital, Trading Volume, and Investor Welfare

In an incomplete market setting with heterogeneous prior beliefs, we show that public information can have a substantial impact on the ex ante cost of capital, trading volume, and investor welfare. In a model with exponential utility investors and an asset with a normally distributed dividend, the Pareto efficient public information system is the system which enjoys the maximum ex ante cost of capital, and the maximum expected abnormal trading volume. The public information system facilitates improved dynamic trading opportunities based on heterogeneously updated posterior beliefs in order to take advantage of the disagreements and the differences in confidence among investors. This leads to a higher growth in the investors' certainty equivalents and, thus, a higher equilibrium interest rate, whereas the ex ante risk premium on the risky asset is unaffected by the informativeness of the public information system. In an effectively complete market setting, in which investors do not need to trade dynamically in order to take full advantage of their differences in beliefs, the ex ante cost of capital and the investor welfare are both higher than in the incomplete market setting, but they are independent of the informativeness of the public information system, and there is no information-contingent trade.