This paper studies asset markets in which ambiguity averse investors face Knightian uncertainty about expected payoffs. The same investors, however, might wish to resolve their uncertainty, although not risk, by just purchasing information. In these markets, uninformed and, hence, ambiguity...

This paper analyzes costly information acquisition in asset markets with Knightian uncertainty about the asset fundamentals. In these markets, acquiring information not only reduces the expected variability of the fundamentals for a given distribution (i.e., risk). It also mitigates the...

We find that a small set of financial columnists has a causal effect on short-term aggregate stock market prices. For some journalists ("bulls") the market reaction is consistently positive, whereas for others ("bears") it is negative. Because bulls and bears are rotated exogenously in our...