Testing Market Efficiency in the Major League Baseball Over-Under Betting Market

Abstract

This article tests market efficiency in the over-under betting market for Major League Baseball using data from the 1996 through 2000 seasons. It is shown that a simple betting strategy based on streaks was profitable for the 1997 season but was not profitable for any of the other years studied. The 1997 season involved expansion, realignment, and the introduction of interleague play to Major League Baseball. These changes in the league’s structure may have created uncertainty in player and team performance, which allowed this strategy to be profitable. The article argues, however, that the over-under betting market for baseball is efficient because the profitability of this strategy was eliminated in the following years.