Not necessarily: a firm's fundamental value increases with uncertainty about average future profitability, and this uncertainty was unusually high in the late 1990s. After calibrating a stock valuation model that takes this uncertainty into account, we compute the level of uncertainty that is needed to match the observed Nasdaq valuations at their peak. The uncertainty we obtain seems plausible because it matches not only the high level but also the high volatility of Nasdaq stock prices. In general, we argue that the level and volatility of stock prices are positively linked through firm-specific uncertainty about average future profitability.

The use of stock-based compensation as a solution to agency problems between shareholders and managers has increased dramatically since the early 1990s. We show that in a dynamic rational expectations model with asymmetric information, stock-based compensation not only induces managers to exert costly effort, but also induces them to conceal bad news about future growth options and to choose suboptimal investment policies to support the pretense. This leads to a severe overvaluation and a subsequent crash in the stock price. Our model produces many predictions that are consistent with the empirical evidence and are relevant to understanding the current crisis.