Sharp money comes from professional bettors, syndicates, or sophisticated bettors who bet based on analysis, not narrative. The betting volume is lower but the average bet size is much larger. Sharp money moves lines because sportsbooks respect it and adjust to reduce their liability against informed bettors.
The key indicator of sharp money is line movement against the public betting percentage. When 70% of bets are on Team A but the line moves toward Team B, that is sharp money on Team B. The sportsbook is adjusting the line to incentivize more bets on Team A, which is where the public is already betting. This tells you that the larger, more informed bets are on Team B.
Reverse line movement is the most reliable sharp money signal. When the public is heavily on one side and the line moves the other direction, sharp money is on the less popular side. This happens because the sportsbook knows that the sharp money is more likely to be correct than the public money, so it adjusts the line to balance liability.
The practical application is to track both the betting percentage and the line movement for every game. If they align (public bets on Team A and line moves toward Team A), that is standard movement. If they diverge (public bets on Team A but line moves toward Team B), that is sharp money. The divergence is the signal. It does not guarantee a winner, but it tells you where the informed money is positioned, which is the most useful information available before a game.