Shadow banking may help drive the day-to-day financial system, but it is a concept looking for a hard-and-fast definition.

Despite coming under intense scrutiny following the financial crisis, there have been disparate characterizations of what the shadow banking sector truly entails — with size estimates ranging from $10 to $60 trillion. At the same time, major regulatory efforts have either been enacted or are in the works to help reduce the size of this important sector, with no agreed-upon way to measure their effectiveness.

The purpose of the Deloitte Shadow Banking Index is to define and quantify the sector over time, including its components. This ongoing effort is designed to more closely measure size, importance, effect of market, and impact of regulatory actions, as well as a way to assess the potential impact of shadow banking on regulated markets.

What is shadow banking really? We started by including a multitude of nonbanking entities and activities and then applied specific criteria. For example, we posit that money market mutual funds (MMMFs) are part of shadow banking as they possess the “money-like” attributes of bank deposits. But they do not have bank-like insurance, nor can they access a central bank for liquidity support.

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