Interest rates on short-term T-bills rose again.

The Treasury Department sold $6.65 billion in three-month bills at an average discount rate of 5.63%, up from 5.47% last week. Another $6.62 billion was sold in six-month bills at an average discount rate of 5.59%, up from 5.51% 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--5.81% for three-month bills with a $10,000 bill selling for $9,857.70, and 5.85% for six-month bills selling for $9,717.40. The discount rate reflects the price discount received when government securities are purchased at less than face value.