The major stock exchanges in the United States observe the following nine holidays:
New Year's Day
Martin Luther King, Jr. Day (third Monday in January)
President's Day (third Monday in February)
Memorial Day (last Monday in May)
Labor Day (first Monday in September)
If the holiday falls on a Saturday, the markets will close on the Friday preceding the holiday unless the Friday is the end of a monthly or annual accounting period. If the holiday falls on a Sunday, the markets will close on the Monday following the holiday.