Six-month T-bill yields rose to a six-month high.

The Treasury Department said rates on six-month bills rose to 9.04%, up from 8.79% at last week’s auction and the highest since Nov. 5, 1984, when they averaged 9.07%. Yields on three-month bills rose to 8.64%, up from 8.48% last week and the highest since March 4, when they averaged 8.73%. A total of $14 billion in securities was sold, divided equally between the two maturities. The new discount rates understate the actual return to investors--8.96% for three-month bills and 9.60% for six-month bills.