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 5.13%, up from 5.08% last week. Another $7 billion was sold in new six-month bills at an average discount rate of 5.22%, up from 5.13% last week. The rates were the highest since three-month bills sold for 5.20% and six-month bills averaged 5.37%, both on Sept. 29. The new discount rates understate the actual return to investors--5.27% for three-month bills, with a $10,000 bill selling for $9,870.30, and 5.44% for six-month bills selling for $9,736.10. The discount rate reflects the price discount received when government securities are purchased at less than face value.