Interest rates on $208 million of Denver International Airport bonds eased this week after rising as high as 12 percent.

The airport's auction-rate bonds reset Wednesday at rates of between 3.99 percent and 7.75 percent, said Margaret Danuser, Denver's debt administrator. Last week, rates rocketed to between 3.5 percent and 12 percent because of turmoil in the nation's financial markets. Rates had averaged between 2 percent and 2.5 percent most of the summer. The spike boosted DIA's interest payments by at least $200,000, according to estimates by the Rocky Mountain News.

The bonds - a fraction of the city's $5 billion of debt - are sold to investors every week in four separate pieces. Last week, there weren't enough buyers for one $52 million piece, meaning the rate on those bonds reverted to the maximum 12 percent level.

"We saw significant improvement this week, but we're still not where we'd like to be," Danuser said. "The market tone is not much better, and probably even worse, this week than last. But we expect that these rates will rachet downward."

The city hopes to convert the $208 million in bonds to variable-rate debt in coming months.