The problems with a second phase of quantitative easing, go back to asking why the first phase hasn't worked to prevent the economy from sliding back. So far the Fed has engaged in buying $1.7 trillion in bonds in that first phase. This shows the limitations of this approach. A lot of money was injected into banks. And the banks have $1 trillion on their books that is not being used for lending. The reason being its hard to find borrowers, as borrowers are cautious and concerned about the economic future. The Quantitative Easing in this second phase is supported by the reasoning that deflation risks remain. But this raises another question, what level of quantitiative easing would work, and would such enormous levels itself cause bigger problems.