Glossary

What is the opening line in sports betting?

Last updated 2026-07-04

The opening line is the first price a sportsbook posts for a game, before public and sharp money begin shaping it. Openers are the linemaker's raw opinion at low limits, and the gap between open and close records everything the market learned in between.

Books open early markets at reduced limits precisely because openers are their most vulnerable numbers: early sharp bets are information the book pays a small price to collect. As money arrives and limits rise, the line hardens toward its efficient close.

Open-to-close movement is the market's paper trail. A team that opened +150 and closed +120 attracted meaningful money; measuring your own bets against that path is the basis of closing line value. Which books post openers first, and who copies whom, is itself a market-structure question worth studying.

The Daily Line Movement Report measures each day's open-to-close moves as its core metric: each book's first and last pre-game capture defines its open and close for the day.

Compute it with the API

curl "https://api.theoddsapi.com/historical/odds?sport_key=basketball_wnba" \
  -H "x-api-key: YOUR_API_KEY"

The earliest snapshot per book per event is its observed opener; the latest pre-game snapshot is its close. Business tier. Free key in minutes.