Central banks can influence the money supply by open market operations. They can increase the money supply by purchasing government securities, such as government bonds or treasury bills. This increases the liquidity in the banking system by converting the illiquid securities of commercial banks into liquid deposits at the central bank. This also causes the price of such securities to rise due to the increased demand, and interest rates to fall. These funds become available to commercial banks for lending, and by the multiplier effect from fractional-reserve banking, loans and bank deposits go up by many times the initial injection of funds into the banking system.