Interest rates on T-bills increased sharply.

The Treasury Department sold $6.61 billion in three-month bills at an average discount rate of 5.47% in this week’s auction, up from 5.40% last week. An additional $6.63 billion was sold in six-month bills at an average discount rate of 5.51%, up from 5.41% last week. The rates were the highest since Feb. 17, when three-month bills sold for 5.66% and six-month bills averaged 5.70%. The new discount rates understate the actual return to investors--5.64% for three-month bills and 5.76% for six-month bills.