T-Bill Yields Hit 11-Month Low: Interest rates on short-term Treasury securities fell at auction to the lowest levels in nearly a year. The Treasury Department sold $11.4 billion in three-month bills at an average discount rate of 5.25%, down from 5.34% last week. Another $11.4 billion was sold in six-month bills at an average discount rate of 5.22%, down from 5.33%. The three-month bill rate was the lowest since 5.07% on Oct. 31. The six-month bill rate was the lowest since they averaged 5.05% on Sept. 19, 1994. The new discount rates understate the actual return to investors--5.41% for three-month bills with a $10,000 bill selling for $9,867.30 and 5.45% for a six-month bill selling for $9,736.10. 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, fell to 5.59% last week from 5.63% the previous week.