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

The Treasury Department sold $7 billion in new three-month bills at an average discount rate of 6.99%, up from 6.92% last week. Another $7 billion was sold in new six-month bills at an average discount rate of 7.06%, up from 7.03% last week. The rates were the highest since three-month bills sold for 7.23% on Jan. 13 and six-month bills averaged 7.14% on Jan. 21. The new discount rates understate the actual return to investors--7.21% for three-month bills, which sold for $9,823.30 with a face value of $10,000, and 7.42% for six-month bills, which sold for $9,643.10. The discount rate reflects the price discount received when government securities are purchased at less than face value.