Two mechanical betting rules that had exposed biases in previous studies were applied to National Football League games for the five consecutive seasons ending with the 2003 Super Bowl. Although bets on home teams produced only break-even results, wagers on underdogs posed a serious challenge to the efficient market hypothesis. One possible explanation is that favorites are no less “public” in the minds of bettors than IBM, GE, and the like are public in the minds of investors and may therefore be the victims of inflated expectations and point spreads.