A fresh reading on inflation showed monthly prices rose more than expected in August, increasing the likelihood the Federal Reserve will raise interest rates next week.
A rebound to $100-a-barrel oil also complicates the picture.
Stripping out volatile food and energy prices — the way the Fed likes to scrutinize underlying inflation — the Consumer Price Index rose 0.3% month over month, compared with expectations for 0.2%. The year-over-year rate was in line with expectations for 2.4%, and down a tenth of a percentage point from July. On a headline basis, CPI rose 3.4% in August, in line with expectations, and 0.4% month over month.
"The upside surprise to core CPI in August means the Fed looks set to hike next week," said Stephen Brown, North America chief economist for Capital Economics.
Markets are now betting on a 90% chance of a rate hike at Wednesday's Fed policy meeting, according to CME FedWatch.