我知open market operation 會令ms 改變,但點解買普通bonds 就推ma?
你嘗試用monetary base而唔係money supply去諗open market operation,咁你就會明白。
Monetary base = Cash held by public + Reserves
例如政府向銀行購買政府債券,銀行擁有的Reserves就會增加,Cash held by public就不變,所以monetary base增加。
但如果Public購買一間銀行自己issue嘅bonds,Reserves就會增加,Cash held by public就會跌,所以monetary base不變。