To fulfill this objective, the main operating target for money market operations was switched from the uncollateralized overnight call rate to the monetary base; it was then decided that the size of the monetary base would rise at  4  In 2010–11, the ECB purchased a limited amount of long-term sovereign bonds under the Securities Markets Programme (SMP), but the equivalent amount of liquidity injected was sterilized.
This measure is aimed at improving the transmission mechanism of the monetary policy as a credit easing policy. The OMTs replaced the SMP. Furthermore, a limited amount of covered bonds were purchased in 2009–10 and 2011–12 in order to ease funding conditions for financial institutions.