The Treasury Department sold $5.77 billion in three-month bills at an average discount rate of 5.010%, up from 4.995% last week. An additional $7.25 billion was sold in six-month bills at an average rate of 5.065%, down from 5.155%. The three-month rate was the highest since May 26, when the bills sold for 5.020%. The six-month rate was the lowest since April 20, when the average was 5.060%. The new discount rates understate the actual return to investors--5.143% for three-month bills, with a $10,000 bill selling for $9,873.40, and 5.271% for a six-month bill selling for $9,743.90. In a separate report, the Federal Reserve Board said the average yield for one-year Treasury bills, the most popular index for making changes in adjustable-rate mortgages, was unchanged at 5.42%.