Short-term T-bill rates fall in sale

The Treasury Department auctioned $20 billion in three-month bills at a discount rate of 3.43%, down from 3.55% last week. An additional $19 billion in six-month bills was auctioned at 3.625%, down from 3.78% last week.

The rates understate the actual return to investors -- 3.518% for three-month bills, with a $10,000 bill selling for $9,913.30, and 3.754% for a six-month bill selling for $9,816.74.

Separately, the Federal Reserve said the average yield for one-year Treasury bills, a popular index for making changes in adjustable-rate mortgages, fell to 3.72% last week from 3.93% the previous week.