Interest rates on short-term Treasury securities rose in auction. The Treasury Department sold $9 billion in three-month bills at a discount rate of 3.885%, up from 3.655% last week. An additional $8 billion was sold in six-month bills at a rate of 3.860%, up from 3.665%. The three-month and the six-month rates were the highest since April 16, when they sold at 4.050% and 4.060%, respectively. The new discount rates understate the actual return to investors--3.978% for three-month bills, with a $10,000 bill selling for $9,901.80, and 3.991% for a six-month bill selling for $9,804.90. The next auction of five-year notes is May 8; May 9 for nine-year, nine-month notes and May 30 for two-year notes.