This paper examines the effects of idiosyncratic accounting information on a firm's cost of capital. By embedding a moral hazard problem into a multifirm asset‐pricing model, I show that moral hazard distorts the sharing of idiosyncratic risk but does not affect the sharing of systematic risk in the economy. A firm‐level improvement in idiosyncratic information reduces the firm's cost of capital even though it does not affect the implied cost of capital inferred from publicly traded shares. Moreover, an economy‐level improvement in idiosyncratic information reduces the risk premium for idiosyncratic risk but increases the risk premium for systematic risk, resulting in an ambiguous net effect on the firm's cost of capital. These results provide alternative explanations for the mixed empirical evidence on the relation between information quality and the cost of capital.

We investigate investors' voluntary disclosure decisions under uncertainty about their information endowment. In our model, an investor may receive initial evidence about a target firm. Conditional on learning the initial evidence, the investor may receive additional evidence that helps them interpret the initial evidence. The investor takes a position in the firm's stock, then voluntarily discloses some or all of their findings, and finally closes their position after the disclosure. We present two main findings. First, the investor will always disclose the initial evidence, even though the market is uncertain about whether the investor possesses such evidence. Second, the investor's disclosure strategy of the additional evidence increases stock price volatility: they disclose extreme news and withhold moderate news. Due to the withholding of the additional evidence, misleading disclosure arises as an equilibrium outcome, where the investor's report decreases (increases) price despite their news being good (bad). These results remain robust when considering the target firm's endogenous response to the investor's report.