I have a very basic question on the somewhat cryptic Open Market Operations. So, from what I understand, say the Fed wants to reduce interest rates (increase monetary base). It will firs buy a bond by writing a cheque to the security holder, the cheque is deposited in a commerical bank, which then deposits this in the central bank. The reserve account of the central bank is credited, and the commercial bank is then able to use these "excess reserves" to create fresh loans- injecting money in the economy. I guess my question is: when the issuer of the bond (say the government) has to pay back to the security holder (central bank), wont it decrease money supply then?