At the conclusion of the first half, sportsbooks will almost always offer a new line for strictly the second half only.
A new point spread and total are issued and the second half is treated as just a single betting event.
Often, the second half spread will mimic the first half line if the game is going to form.
However, if one of the two teams has a substantial advantage in relation to the full-game line, oddsmakers will often try to place the spread in accordance with the current game situation and probabilities for a return to the means.
When betting a second-half point spread, total, or team total, it should be noted that if the game is tied at the end of the fourth quarter, any scoring in a subsequent overtime period(s) are added to the second half score.
Some sports bettors will use second-half wagering as a means to hedge a profit should their wagers appear ahead at halftime.
For example, a bettor that has a wager on the OVER for the full game at 215 may elect to place a wager on the UNDER if there was excess scoring in the first half.
If the final result of the scoring in the first half was 115, a bettor could comfortable come back on almost any offered number for a strong middle opportunity, possibly gaining as much as a 200 percent win for a risk as low as five percent of the total amount of the two wagers combined.