The answer may surprise you.
CME Bitcoin Futures close at 4:00 pm Central Time on the last Friday of every month. This is one hour earlier than the close of regular futures contracts on other exchanges.
The reason for this is that CME Bitcoin Futures are based on the Bitcoin Reference Rate (BRR), which is calculated by Bitstamp, GDAX, Kraken, and itBit at 4:00 pm GMT on the last Friday of every month.
As such, CME Bitcoin Futures close one hour earlier in order to align with the BRR calculation.
So, if you’re trading CME Bitcoin Futures, be sure to take this into account when planning your trades. And, as always, make sure to do your own research and consult with a financial advisor before making any investment decisions.