R. W. Hafer investigates several aspects of the efficient markets hypothesis: Do stock prices react only to unanticipated changes in the money stock? Are the magnitudes of these effects different across different monetary policy procedures? Do different measures of stock prices react differently to a given unexpected change in M1? Are the different stock price measures equally responsive to a given change in the discount rate? Finally, do reactions to discount rate changes vary across monetary policy procedures? Hafer’s results, based on daily data from 1977 through 1979, generally do not reject the efficient markets hypothesis. He does find, however, that the response to an unexpected increase in M1 is different from an unexpected decrease in Ml for the broader stock price measures. Hafer’s evidence also indicates that the response to discount rate changes varies across stock price measures and monetary policy procedures.