This thesis investigates the role of information uncertainty in determining the stock price performance and managers' equity nancing decisions. The previous literature documents the experimental evidence of significant impact of information uncertainty on investors' preference and decision making. The first empirical examines the interaction effect between information uncertainty and underreaction anomaly in UK stock market. The empirical evidence is consistent with behavioral finance theory that stocks with higher information uncertainty have greater abnormal adjusted returns, especially following bad news. Chapter 4 further tests the role of information uncertainty in cross-sectional stock returns within 30 global stock markets. The evidence confirms my conjecture that both growth options and information asymmetry are attributes to the information uncertainty. The empirical findings show that stocks with higher information uncertainty have lower future stock returns after controlling for information asymmetry and other characteristics of market and firm. Chapter 5 reports a positive correlation between information uncertainty and probability of equity issuance among industry firms in US market. The evidence shows that information uncertainty does not only affect the stock price performance, but also have in uence in managers' equity financing decisions. Overall, our empirical work contributes to the literature with conclusive evidence that information uncertainty amplifies the extent of stock mispricing, which is consistent with behavioral nance and is in contrast to predictions of neoclassic finance theory.