* * *  INTRODUCTION About a decade ago we saw the first signs of turbulence in global financial markets. A year later Lehman Brothers went under. We were faced with a full-blown financial crisis. Later, it was named the Great Financial Crisis.
It led to a both qualitative and quantitative change in the operations of central banks and was reflected in their balance sheets. The events forced the central banks to focus on the question what kind of credit they extended, and should extend, in providing liquidity to private banks. Later, the central banks launched large securities purchase programs.