The Buffett indicator (or the Buffett metric, or the Market capitalization-to-GDP ratio), is a valuation multiple used to assess how expensive or cheap the aggregate stock market is at a given point in time. It was proposed as a metric by investor Warren Buffett in 2001, who called it "probably the best single measure of where valuations stand at any given moment", and its modern form compares the capitalization of the US Wilshire 5000 index to US GDP. It is widely followed by the financial media as a valuation measure for the US market in both its absolute, and de-trended forms.