The Treasury Department sold $6.3 billion in new three-month bills at an average discount rate of 5.20%, down from 5.25% last week. Another $6.3 billion was sold in new six-month bills at an average discount rate of 5.37%, down from last week's 5.39%. The rates were the lowest since Aug. 15, when three-month bills sold for 5.16% and six-month bills averaged 5.34%. The new discount rates understate the actual return to investors--5.34% for three-month bills and 5.60% for six-month bills. The discount rate reflects the price discount received when government securities are purchased at less than face value.