Jayant V. Ganguli

Complementarities, Multiplicity, and Supply Information

If traders can obtain private information about the payoff and the supply of a stock then there can exist (i) complementarity in information acquisition and (ii) multiple equilibria in the financial and information markets. The additional dimension of supply information increases coordination possibilities in the financial market, leading to multiple equilibria. The existence of two information sources can lead to information acquisition being complementary. The multiplicity of equilibria is suggestive of excess volatility and crashes. The different financial market equilibria imply differing patterns of cost of capital and volume of trade. (JEL: D82, D83, G14) (c) 2009 by the European Economic Association.

The Pricing Effects of Ambiguous Private Information

When private information is observed by ambiguity averse investors, asset prices may be informationally inefficient in rational expectations equilibrium. This inefficiency implies lower asset prices as uninformed investors require a premium to hold assets and higher return volatility relative to informationally efficient benchmarks. Moreover, asset returns are negatively skewed and may be leptokurtic. Inefficiency also leads to amplification in price of small changes in news, relative to informationally efficient benchmarks. Public information affects the nature of unrevealed private information and the informational inefficiency of prices. Asset prices may be lower (higher) with good (bad) public information.

Universal interactive preferences

We prove that a universal preference type space exists under much more general conditions than those postulated by Epstein and Wang (1996). To wit, it is enough that preferences can be encoded by a countable collection of continuous functionals, while the preferences themselves need not necessarily be continuous or regular, like, e.g., in the case of lexicographic preferences. The proof relies on a far-reaching generalization of a method developed by Heifetz and Samet (1998).

Common p-belief and uncertainty

This note generalizes the notion of common p-beliefs to situations of ambiguity or Knightian uncertainty. When players have multiple prior beliefs, we show that Aumanns no-agreement theorem can be approximated. We also provide conditions under which purely speculative trade does not occur in the presence of ambiguity when players preferences are complete or incomplete.