Long Term Perspective
The spread between the 6-month Treasury bill and the federal funds rate is also negative. This means that the yield on the 6-month bill tends to be lower than the fed funds rate. In the 1980s, this spread averaged -15 basis points, but averaged zero basis points in the 1990s.

Short Term Perspective
Between 2000 and 2002, the yield on the 6-month Treasury bill was 16 basis points below the federal funds rate, on average. The gap between the 6-month bill and the federal funds rate is virtually zero from July through October.