First-half and second-half markets

Each half carries its own spread, total and moneyline, settling only on the points scored inside that half. First-half markets are posted before the event; second-half markets are usually posted at the interval, repriced from scratch with the first-half result already known. They settle independently of the full-game bet and of each other.

A half is a shorter sample, so its line is a fraction of the full-game number — but not a clean half, because the two halves are not statistically the same object. Second halves contain the clock management, the substitutions and the garbage time, so the market prices them as a different kind of period rather than a repeat of the first.

Overtime attribution varies and matters. In basketball an overtime period normally counts toward second-half and full-game bets; in several sports it does not count toward the second half at all, and in others the second-half market is explicitly regulation only. The rule is per book and per sport.

Here is the catch. The most common mistake is treating a half line as arithmetic on the full line and betting the difference. The second-half number posted at the interval is a fresh price with a fresh margin, built from the live game rather than subtracted from the pre-game total.

What to do with it. State what the second half alone has to do, ignore the first half entirely, and confirm the overtime rule before placing.