U.S. big banks help provide short-term dollar money during times of need, like the end of the month or when the U.S. government has more money. They do this by moving money around within their own bank groups. They also reduce the extra money they keep at the Federal Reserve to help out. In 2019, there was a sudden increase in the need for short-term money, but the big banks were able to handle it with help from the Federal Reserve.