What the contract terms say
The crypto contract terms define the value that settles each contract as:
“the spot price of one <cryptocurrency> in U.S. dollars at <time>, according to a simple average of the CF <cryptocurrency> <index> for the 60 seconds prior to <time>”
The source is a CF Benchmarks index, and the same template covers each crypto series. Revisions to the index made after expiration do not count.
The last print is not the result
In the final minute, the price you watch and the price that settles can disagree. A contract asking whether Bitcoin will be above a strike can settle YES even though the last print was below the strike, if the price spent most of the final minute above it. The reverse happens too.
The index publishes about once a second, so the window holds about 60 values, and the settlement value is their simple average.
Part of the answer is already fixed
Once the final minute starts, every second that passes locks in part of the average. With 30 seconds gone, half of the settlement value is already decided, and only the other half can still move. Put as a formula, with f the fraction of the window already elapsed:
expected settlement = f × average so far + (1 − f) × current priceThat is why a late spike moves the settlement value far less than it moves the last print. A price that jumps in the last five seconds shifts the average by only a twelfth of the jump.
Prices can be finer than a cent
The contract allows prices in steps of $0.001. In practice, prices away from the ends of the range trade in whole cents, and tenths of a cent appear near the ends, above 90 cents and below 10 cents.