Definition
Sharp money refers to bets placed by professional or highly sophisticated bettors whose wagers cause books to move lines. Sharps bet large volume, exploit mispriced lines quickly, and are identified by their ability to consistently beat closing prices. Books respect sharp action and adjust rather than taking the other side of a sharp's position. "Steam moves" occur when sharp syndicates hit the same side simultaneously across multiple books, causing rapid coordinated line movement. Public money rarely moves lines; sharp money always does.
Worked Example
Game opens Patriots −3 (−110). 70% of bets are on Patriots, but line moves to Patriots −2. Reverse line movement — line moved opposite to public bet percentage. This signals sharp money bet the Giants +3 side, outweighing the larger volume of public Patriots action. Books respected the sharp positions. Bettors who follow steam: take Giants +3 before it moves further to +2 or +1.5.
Why It Matters
Reverse line movement and steam detection identify where sharp money is pointing. Following sharp action doesn't guarantee wins, but it tracks with positive CLV significantly more often than fading it.