Short-term T-bill rates mixed in sale

The Treasury Department auctioned $15 billion in three-month bills at a discount rate of 4.79%, up from 4.685% last week. An additional $14 billion in six-month bills was auctioned at a discount rate of 4.81%, the same as last week.

The new discount rates understate the actual return to investors -- 4.93% for three-month bills, with a $10,000 bill selling for $9,878.92, and 5.012% for a six-month bill selling for $9,756.83.

Separately, the Federal Reserve said the average yield for one-year Treasury bills, a popular index for making changes in adjustable-rate mortgages, edged down to 4.94% last week from 4.95% the previous week.