WASHINGTON | Interest rates on short-term Treasury bills fell in Monday's auction to the lowest levels on record.

The Treasury Department auctioned $28 billion in three-month bills at a discount rate of 0.050 percent, down from 0.150 percent last week. Another $28 billion in six-month bills was auctioned at a discount rate of 0.430 percent, down from 0.490 percent last week.

Both the three-month rate and the six-month rate were at all-time lows.

The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,998.74 while a six-month bill sold for $9,978.26. That would equal an annualized rate of 0.051 percent for the three-month bills and 0.437 percent for the six-month bills.

Separately, the Federal Reserve said Monday that the average yield for one-year Treasury bills, a popular index for making changes in adjustable rate mortgages, fell to 0.93 percent last week from 0.96 percent the previous week.