There is much evidence available showing that interest rates rise in response to unexpectedly large money stock (M1) announcements [3;6; 12; 14; 15; 16]. Some studies that have examined the interest rate response to monetary base announcements, however, have failed to isolate any systematic response to these surprises [4;5]. Such a finding warrants further consideration. Many believe that the monetary base is a good summary measure of monetary policy. Others argue that the monetary base is an accurate indicator of future inflation [7]. Since both a policy anticipation effect and an inflationary expectation effect have been offered to explain why money stock announcements affect interest rates, it would appear that monetary base announcements should also matter. The nonexistence of a monetary base announcement effect is especially difficult to understand since the monetary base, for a given statement week, is announced one week prior to the money stock number for that same week. This suggests the financial markets may be inefficient in processing information. An important aim of the present paper is to consider the information content of monetary base announcements. The first section of this paper argues that the monetary base may not be the pure monetary policy indicator some suggest. In particular, under a lagged reserve accounting system, many of the subsequent innovations in the base can be foretold by earlier money stock announcements. Contrary to suggestions of earlier analysis, the money stock announcements are likely to lead monetary base announcements. Also, of importance is the recognition that the monetary base includes currency and discount window borrowings. Since the Fed does not try to exercise short-term control over either of these elements of the base, their movements will not reflect policy actions. The analysis of monetary base announcements suggests that Federal Reserve announcements of discount window borrowing, however, may carry important information to financial markets, over and above the money supply announcement. While discount window borrowings are included in the monetary base, it is felt that this element alone carries important information to the financial community. The third section of this paper investigates whether or not the unexpected element of these borrowing announcements has an