The degree of potential moral hazard created will depend on the instrument chosen. Policy actions that work through the overall market rather than through individual firms create a lower probability of distorting risk taking. Thus, a first resort in managing a crisis is to use open market operations to make sure aggregate liquidity is adequate. Adequate liquidity has two aspects: First, we must meet any extra demands for liquidity that might arise from a flight to safety; if such demands are not satisfied, financial markets will tighten at exactly the wrong moment. This was, for example, an important consideration after the stock market crash of 1987, when demand for liquid deposits raised the demand for reserves held at the Fed; and again after 9/11, when the loss of life and destruction of infrastructure impeded the flow of credit and liquidity.
Second, we must determine whether the stance of monetary policy should be adjusted to counteract the effects on the economy of tighter credit supplies and other knock-on effects of financial instability...
Other policy instruments that can be used to deal with financial instability--discount window lending, moral suasion aimed at convincing private parties to keep credit flowing, actions to keep open or slowly wind down troubled institutions--are, in my judgment, more likely than open market operations or monetary policy adjustments to have undesirable and distortionary effects. Hence, they should be, and are, used only after a finding that broader instruments, like open market operations, are unlikely to prevent significant economic disruption.