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

The Treasury Department sold $6.8 billion in new three-month bills at an average discount rate of 5.58%, up from 5.44% last week. Another $6.8 billion was sold in new six-month bills at an average discount rate of 5.59%, up from 5.43% last week. The rates were the highest since Dec. 29, when three-month bills and six-month bills both averaged 5.68%.The new discount rates understate the actual return to investors--5.74% for three-month bills with a $10,000 bill selling for $9,859.00 and 5.83% 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.