When CME bitcoin futures expire, the holder of the contract is obliged to deliver the underlying asset, cash-settled in US dollars, to the exchange on the specified delivery date. The settlement price is calculated using a price index, with the final settlement price being published by 4:00 p.m.
London time on the last trading day. If the delivery date falls on a weekend or holiday, then delivery and settlement take place on the next business day.
When futures contracts expire, there is often a scramble to buy or sell the underlying asset in order to avoid having to make or take delivery. This can result in volatile prices as participants rush to square their positions.
For bitcoin futures, this effect may be amplified by the fact that there is no centralized market for bitcoin and so prices can vary widely between exchanges.
The expiration of CME bitcoin futures may also have an impact on the price of bitcoin itself as holders of expiring contracts may attempt to buy or sell bitcoin in order to avoid having to make or take delivery. This could lead to volatility in the spot market as well as the futures market.