Interest rates on short-term Treasury securities rose in Monday's auction.
The Treasury Department sold $21 billion in three-month bills at a discount rate of 2.045 percent, up from 1.950 percent last week.
An additional $19 billion was sold in six-month bills at a rate of 2.260 percent, up from 2.140 percent.
The new discount rates understate the actual return to investors -- 2.084 percent for three-month bills with a $10,000 bill selling for $9,948.88, and 2.318 percent for a six-month bill selling for $9,886.37.
In another auction, yields on three-year Treasury notes also rose. The yield was 3.090 percent, up from 2.842 percent at the last auction on Aug. 9. The notes carry a coupon interest rate of 3 percent with each $10,000 in face value selling for $9,974.40.
The Federal Reserve, meanwhile, said the average yield for one-year constant maturity Treasury bills, a popular index for making changes in adjustable rate mortgages, rose to 2.35 percent last week from 2.27 percent the previous week.