The Treasury Department auctioned $30 billion in three-month bills at a discount rate of 0.050 percent, down from 0.055 percent last week. Another $25 billion in six-month bills was auctioned at a discount rate of 0.075 percent, unchanged from last week.
The three-month rate was the lowest since these bills averaged 0.040 percent two weeks ago on Aug. 5.
The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,998.74 while a six-month bill sold for $9,996.21. That would equal an annualized rate of 0.051 percent for the three-month bills and 0.076 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 to adjustable-rate mortgages, was 0.12 percent last week. That's unchanged from the previous week.