A Simple Model of Capital Market Equilibrium with Incomplete Information

TLDR: The model financial economics encompasses finance, micro-investment theory and much of the economics of uncertainty as mentioned in this paper, and it has had a direct and significant influence on practice, as is evident from its influence on other branches of economics including public finance, industrial organization and monetary theory.

Abstract: THE SPHERE of model financial economics encompasses finance, micro investment theory and much of the economics of uncertainty. As is evident from its influence on other branches of economics including public finance, industrial organization and monetary theory, the boundaries of this sphere are both permeable and flexible. The complex interactions of time and uncertainty guarantee intellectual challenge and intrinsic excitement to the study of financial economics. Indeed, the mathematics of the subject contain some of the most interesting applications of probability and optimization theory. But for all its mathematical refinement, the research has nevertheless had a direct and significant influence on practice. ’ It was not always thus. Thirty years ago, finance theory was little more than a collection of anecdotes, rules of thumb, and manipulations of accounting data with an almost exclusive focus on corporate financial management. There is no need in this meeting of the guild to recount the subsequent evolution from this conceptual potpourri to a rigorous economic theory subjected to systematic empirical examination? Nor is there a need on this occasion to document the wide-ranging impact of the research on finance practice.2 I simply note that the conjoining of intrinsic intellectual interest with extrinsic application is a prevailing theme of research in financial economics. The later stages of this successful evolution have however been marked by a substantial accumulation of empirical anomalies; discoveries of theoretical inconsistencies; and a well-founded concern about the statistical power of many of the test methodologies.3 Finance thus finds itself today in the seemingly-paradoxical position of having more questions and empirical puzzles than at the start of its