Bernanke and gertler (2001) reach a different conclusion. They allow fundamental shocks such as a technology innovation that raises productivity and profits to also be a source of movement in stock prices. They assume that the central bank cannot tell whether an increase in stock prices is driven by a bubble shock or a fundamental shock. Since both types of shocks ultimately affect real output and inflation . they conclude that the central bank can do just as well by responding only to those goal variable. They find no significant additional benefit to responding directly to stock prices.