THANKS TO whoever created an obscure piece of New York Stock Exchange red tape – officially known as Rule 7.2 – U.S. equity markets won't commemorate the start of 2022 with a holiday.
The rule stipulates that when a holiday falls on a Saturday, the market will close on the preceding Friday — unless, that is, “unusual business conditions exist, such as the ending of a monthly or yearly accounting period.” Since Dec. 31 marks the end of the month, quarter and year, that means a full session on New Year's Eve and no day off on the following Monday.
— Bloomberg Markets