Definition
A first-half or first-quarter bet is a wager on only that part of the game, not the final score. In football or basketball, a first-half spread, total, or moneyline is graded when the second quarter ends. A first-quarter bet is graded when the first quarter ends.
For negative American odds, the win amount is:
stake * (100 / absolute odds)
At -110, a $110 stake wins $100, for a $210 total return if the bet wins.
Worked Example
A sportsbook lists:
Lakers 1st Half -2.5 (-110)
You bet $110. The Lakers lead by 4 at halftime, so the bet wins and returns $210: your $110 stake plus $100 profit.
If the Lakers lead by exactly 2 at halftime, the bet loses because -2.5 requires them to lead by 3 or more. The final game score does not matter.
Why It Matters
First-half and first-quarter markets help isolate matchups, pace, injuries, rotations, or game plans that show up early but may not hold for the full game. They are useful when your read is tied to a specific segment instead of the full result.