Line movement

Line movement is the record of how a sportsbook's price on an outcome shifts from the moment a market opens to the moment it closes. Books adjust prices in response to the volume and direction of money wagered, new information such as injuries or lineup changes, and their own desire to manage risk exposure across a market.

This differs from overround, which is the margin built into a price at any single moment; line movement instead describes how that price, margin included, changes over the life of the market. A key driver of movement is sharp money, wagers from bettors a book has identified as historically accurate, which sportsbooks often weight more heavily than the sheer number of public bets when deciding whether to move a line, since a lopsided bet count does not necessarily mean lopsided financial risk to the book.

Bettors track line movement to infer where informed money is going and to time their own bets ahead of an anticipated shift, and the price just before an event begins, the closing line, is the reference point for closing line value. A common pitfall is assuming all movement reflects new information about the event; some movement is simply a book managing its own inventory and balancing exposure across both sides of a bet, not a signal about who is right.