One question that again will be important: What matters for long-term interest rates, the stock of bonds held by the central bank or the flow of bonds purchased by the central bank?

In the near future, the Federal Reserve and the ECB will reduce and then stop their bond purchases. What impact will this decision have on long-term interest rates? It will be small if what matters is the stock of bonds held by the central bank; they are not going to reduce the size of their balance sheets; It will be strong if what matters is the flow of bonds purchased by the central bank. In theory, long-term interest rates result from a stock equilibrium (between demand and supply of bonds in stock). Econometric analysis shows that it is the stock of bonds held by the central bank and not its purchases of bonds that influences the long-term interest rate.