Most home stadiums/arenas of major-sport teams in the U.S. are sponsored by large publicly traded companies. Using NFL data we find that stock returns to the sponsoring firms are affected by the outcomes of games played in their stadiums. Wins in Monday night games generate next-day abnormal returns 50 basis points higher than losses. The effect is 80 basis points in the post-season and when the game outcome is unexpected. This does not revert over the next few days. Outcomes of NFL games could serve as a reasonably exogenous instrument for investor sentiment.