Futures liquidation is said to be an accounting entry.
There is a special clearing account for futures, which is opened in a futures company, and a tripartite custody agreement is signed between the bank account and the futures account. The margin account is such a futures account. Because the money deposited in the futures account does not belong to the bank, it cannot be included in the bank deposit, but the money has not actually bought futures, so it is accounted for by the deposit account.