Tournaments
Overlay in poker
Definition
The shortfall when a tournament's guaranteed prize pool is larger than the buy-ins collected; the room pays the difference.
When a tournament has a guaranteed prize pool (GTD) and too few players register, the room adds the missing money. The overlay is extra value for the players, because the prize pool is bigger than the buy-ins.
Players look for overlays: an event with a large overlay has a positive expected value for everyone in the field.
Example
A $10,000 guarantee with only $8,000 in buy-ins has a $2,000 overlay.