“…Indeed, one can be overwhelmed by trying to contend with all the different types of heterogeneity that can arise in financial markets-heterogeneity in risk attitude, in impatience, in probability assignment, in transmission of information, in network connectivity, in information processing speed, and so on. See Brown & Rogers [2], Duffie [3], Ziegler [4], and references cited therein, for overviews of some of the issues connected to heterogeneity in financial markets currently being pursued. There is also a large literature devoted to portfolio management under partial information (see, for example, Björk et al [5] and references cited therein).…”