In a world of heterogeneous investors, a competitive financial market has two major functions. First, it is the mechanism by which ownership of the existing supply of risky assets is distributed among investors. This is the role which is analyzed in detail by the standard Capital Asset Pricing Model (CAPM) and its many extensions. The second important market function is to aggregate the diverse information held by different investors into a single price. Most versions of the CAPM eliminate the information aggregation function by assuming that investors hold homogeneous beliefs with respect to the probability distribution of asset returns. Exceptions which deal with some aspects of the problem are Lintner , Grossman , Grossman and Stiglitz , and Figlewski [1, 3 ].