Interest rates highest in decade at weekly Treasury auction

Interest rates on short-term U.S. Treasury bills rose in Monday's auction to their highest levels in a decade.

The Treasury Department auctioned $48 billion in three-month bills at a discount rate of 1.945 percent, up from 1.940 percent last week. Another $42 billion in six-month bills was auctioned at a discount rate of 2.100 percent, up from 2.085 percent last week.

The three-month rate was the highest since those bills averaged 2.050 percent on June 16, 2008, before the onset of the financial crisis. The six-month rate was the highest since it averaged 2.135 percent on June 30, 2008.

The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,951.83 while a six-month bill sold for $9,894.83. That would equal an annualized rate of 1.982 percent for the three-month bills and 2.152 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, stood at 2.34 percent on Friday, unchanged from the beginning of last week on July 2.