After-hours pricing in foreign equity markets of multiple-listed U.S. securities appeared to be efficient in predicting New York prices in the weeks immediately following the October 1987 crash, but relatively uninformative in succeeding months. By contrast, daily changes in New York prices...

A standard macroeconomic specification is that the aggregate economy is directed by a single, smart representative agent using optimal decision rules. This paper explores an alternative conjecture--that the dynamic behavior of markets is often better interpreted as the interactions of many...