I am wondering about how Fed/government manipulate the Treasury bills. Since I read news that Fed stimulate the economy through buying bonds, which provide liquidty to market. On the other side, central bank also issue new Treasury bills to borrow money, which form huge indebtness.
I am so confused that in the first method, yields are generally lower since more demand on bond; while in the second one, this should lead to a higher yield again? Doesnt it contradict with their own behavior for regulating market?
Who could help me, and I know it's silly question.