This paper investigates whether there are benefits in terms of higher economic stability from incorporating stock prices into the price index targeted by the central banks. It also looks into the question of whether central banks should use stock prices as a component of the output stability index and how the index can be constructed. An optimization technique is employed to estimate weights for the various sectoral prices. The obtained weights, which depend on sectoral parameters, differ from those used in the construction of the consumer price index, CPI. Using data from the UK and the US, our analysis demonstrates that in comparison to the CPI, our measure of inflation leads to a higher output stability. Thus, in an inflation-targeting monetary policy environment, it is important to adopt a broader inflation benchmark than the CPI for the general macroeconomic stability.