Rates fall at weekly Treasury bill auction WASHINGTON (AP) - Interest rates on short-term Treasury bills fell in Monday's auction. The Treasury Department auctioned $29 billion in three-month bills at a discount rate of 0.01 percent, down from 0.015 percent last week. Another $27 billion in six-month bills was auctioned at a discount rate of 0.05 percent, down from 0.055 percent last week. The three-month rate was the lowest since these bills averaged 0.005 percent on Dec. 19. The six-month rate was the lowest since these bills averaged 0.04 percent, also on Dec. 19. The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,999.75 while a six-month bill sold for $9,997.47. That would equal an annualized rate of 0.010 percent for the three-month bills and 0.051 percent for the six-month bills. Separately, the Federal Reserve said Monday that the average yield for one-year Treasury bills, a popular index for making changes in adjustable rate mortgages, was unchanged at 0.12 percent last week, the same as the previous week.