The Federal Reserve in the U.S. requires banks to keep a certain amount of money in reserves. Over the years, they have reduced these requirements, which has led to concerns about stability in the financial markets. However, despite these reductions, the impact on overnight markets has been minimal due to banks using other methods to manage their reserves. Retail sweep programs have been used to avoid reserve regulations, but they are seen as inefficient and costly. Some countries have adopted operating procedures without explicit reserve requirements as a potential solution.