Saturday, March 20, 2010

Greenspan, Mankiw, Leverage and Classical Banking

In his comments on Alan Greenspan's paper The Crisis, presented at the spring meeting of the Brookings Papers on Economic Activity, Greg Mankiw posts very stimulating and new thoughts on the links between the Modigliani-Miller theorem, leverage, and the “narrow banking” proposal.


“Indeed, I think it is possible to imagine a bank with almost no leverage at all. Suppose we were to require banks to hold 100 percent reserves against demand deposits. And suppose that all bank loans had to be financed 100 percent with bank capital. A bank would, in essence, be a marriage of a super-safe money market mutual fund with an unlevered finance company. (This system is, I believe, similar to what is sometimes called “narrow banking.”) It seems to me that a banking system operating under such strict regulations could well perform the crucial economic function of financial intermediation. No leverage would be required.

One thing such a system would do is forgo the “maturity transformation” function of the current financial system. That is, many banks and other intermediaries now borrow short and lend long. The issue I am wrestling with is whether this maturity transformation is a crucial feature of a successful financial system. The resulting maturity mismatch seems to be a central element of banking panics and financial crises. The open question in my mind is what value it has and whether the benefits of our current highly leveraged financial system exceed the all-too-obvious costs.”

Read the whole post here.

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