Quarter and period markets

The same three markets applied to a quarter, a period or an inning, settling strictly on the scoring inside that segment. The numbers are small, the lines are short, and the derivation from the full-game number is automatic. Everything before the segment starts and everything after it ends is irrelevant to settlement.

Segment markets exist because the segment is a natural unit and because the book can generate them at no modelling cost from the game total. The shorter the segment, the larger the share of its outcome that is simple variance, which is why margins on them run wider than on the market they were derived from.

Segments are not scaled copies of the game. A basketball fourth quarter contains deliberate fouling in close games and empty benches in blowouts, which pushes its scoring to two separate clusters rather than one — a shape the game total does not have and a quarter total cannot express.

Here is the catch. Overtime is the standard settlement trap. Fourth-quarter and final-period bets almost always settle on regulation only, while the game and second-half markets include overtime, so a game that goes to an extra period settles those markets differently from one another.

What to do with it. Confirm the overtime rule for the exact segment, and check whether the segment's scoring pattern actually resembles the game's before treating the line as a scaled-down total.