Extensive-form market games typically have a large number of noncompetitive equilibria. In this paper, we argue that the complexity of noncompetitive behavior provides a justification for competitive equilibrium in the sense that if rational agents have an aversion to complexity (at the margin),...

The authors describe a model of general equilibrium with incomplete markets in which firms can innovate by issuing arbitrary, costly securities. When short sales are prohibited, firms behave competitively and equilibrium is efficient. When short sales are allowed, these classical properties may...

A complex financial system comprises both financial markets and financial intermediaries. We distinguish financial intermediaries according to whether they issue complete contingent contracts or incomplete contracts. Intermediaries such as banks that issue incomplete contracts, e.g., demand...

The authors characterize the symmetric equilibria of an investment game with a pure informational externality. When the period length is very short, the game ends very quickly; with positive probability, an informational cascade (herding) causes an investment collapse. As the period length...