The ability, and indeed the obligation, to steer the money markets in order to deliver macroeconomic stability adds an important extra twist to the risk management problem: the central bank is not just price taker in the financial markets, it is a price maker too. This is one of the features that make them special as investors and lenders.
One may see it as a sort of paradox that central banks, in making policy, themselves seem to create and control much of the risk they themselves bear as investors and creditors. However, the central banks do not actually have arbitrary powers to steer the interest rates or other market prices.