The term was coined in 1997–99 by Deutsche Bank analyst Dr. Edward Yardeni commenting on a report on the July 1997 Humphrey-Hawkins testimony by the then-Fed Chair, Alan Greenspan on equity valuations. In 2014, Yardeni noted that the predictive power of the Fed model stopped working almost as soon as he noted the relationship. The term was never formally endorsed by the Fed, however, Greenspan made further references to the relationship. In December 2020, the Fed Chair Jerome Powell, invoked the relationship to justify stock market valuations that were approaching levels not seen since the 1999–2000 Dot-com bubble or the 1929 market bubble, due to exceptional monetary looseness by the Fed.