Evidence on the Speed of Convergence to Market Efficiency by Tarun Chordia, Richard Roll, and Avanidhar Subrahmanyam April 11, 2004 Abstract Daily returns for stocks listed on the New York Exchange (NYSE) are not serially dependent. In contrast, order imbalances on the same stocks are highly persistent from day to day. These two empirical facts can be reconciled if sophisticated investors react to order imbalances within the trading day by engaging in countervailing trades sufficient to remove serial dependence over the daily horizon. How long does this actually take? The pattern of intra-day serial dependence, over intervals ranging from five minutes to one hour, reveals traces of efficiency-creating actions. For the actively-traded NYSE stocks in our sample, it takes longer than five minutes for astute investors to begin such activities. By thirty minutes, they are well along on their daily quest. Contacts Chordia Roll Subrahmanyam Voice: 1-404-727-1620 1-310-825-6118 1-310-825-5355 Fax: 1-404-727-5238 1-310-206-8404 1-310-206-5455 E-mail:
[email protected] [email protected] [email protected] Address: Goizueta Business School Anderson School Anderson School Emory University UCLA UCLA Atlanta, GA 30322 Los Angeles, CA 90095-1481 Los Angeles, CA 90095-1481 We are grateful to Michael Brennan, Jeff Busse, Eugene Fama, Laura Frieder, Will Goetzmann, Clifton Green, Andrew Karolyi, Pete Kyle, Francis Longstaff, Steve Ross, Ross Valkanov, Kumar Venkatraman, Ingrid Werner, and seminar participants at Bocconi University, Princeton University, Southern Methodist University, Texas A&M University, the New York Stock Exchange, the 2002 Western Finance Association Conference, and the 2002 University of Maryland Finance Conference for valuable comments and suggestions.