We examine empirically whether financial asset prices may be admitted into the ECB interest rate rule. A correctly specified monetary policy rule implying that the ECB reacts to stock prices movements must include some measure of the gap between actual stock prices and fundamental values. We develop an original methodology to measure such a deviation, and we employed it as argument in an augmented interest rate rule. The empirical evidence suggests the following description of the European central banker: he significantly reacts to financial asset prices, by raising (lowering) the ECB main interest rate when stock prices are over(under)-evaluated; he is partisan of a wait-and-see policy, reacting only when the price gap is quite important; and he seems rather little conservative, believing that asset prices are driven mainly by nonfundamental factors.
