Everyone who backed the winning trader shares the pool, in proportion to how much they staked.

The calculation

In words: your share of everything backed on the winning trader is your share of the pool. Back a fifth of the winning side and you take a fifth of the pool. The fee itself is covered in Fees on Incept. Backs on any other trader pay nothing.

Worked through with real numbers

A round attracts 10,000 XP in total. After the platform fee of 300 XP, 9,700 XP is left to share out: Trader C wins. You staked 100 XP on Trader C.
Your 100 XP came back as 970 XP, because hardly anyone else picked Trader C. Same pool, same 100 XP stake, but Trader B wins instead. Trader B had 5,000 XP on it.
Same race, same stake, very different result.

When you get paid

Automatically, shortly after the race ends and every trader’s final numbers have been confirmed. There is no claim step. Winning stakes are unlocked and winnings are added to your balance in one go. Losing stakes are taken at the same moment.

Two results that surprise people

If every back in a round was on the trader that won, there are no losing stakes to share out. Everyone receives their own stake back, minus the platform fee, so you end up a little below what you put in.This is deliberate. The fee is charged on the whole pool rather than just the losing side, so a round can never settle with nothing collected.
If every back was on a trader that lost, there is no winning side to pay. The round finishes normally, records its winner, every back pays nothing, and the whole pool goes to the fee.This is not a cancelled round and there is no refund. The race produced a clean result. The crowd simply all got it wrong.