What happens to the money supply when the fed sells treasuries?

When the Federal Reserve sells treasuries, it decreases the money supply in the economy. This occurs because the buyers of the treasuries pay for them using their bank reserves, which reduces the amount of reserves in the banking system. As a result, banks have less capacity to create loans, leading to a contraction in overall money supply. This action is typically part of a strategy to combat inflation or cool down an overheated economy.