(Updates with index/price moves, macroeconomic data, and geopolitical news from the first paragraph.)
US equity indexes fell amid concerns that surging crude oil prices and higher government bond yields risk undermining consumer and corporate investment.
The Nasdaq Composite fell 0.5% to 27,405.7, the S&P 500 declined 0.3% to 7,781.4, and the Dow Jones Industrial Average slid 0.2% to 51,075.9 after midday Thursday.
Tankers are facing a higher risk of attacks and intimidation as they try to get critical shipments through the Strait of Hormuz after Iran issued new warnings that it would block routes that it has not authorized, sources told Reuters.
Tropical Storm Isaias continues to strengthen ahead of landfall on the northern Gulf Coast by this weekend, CNN reported. The storm rapidly intensified into the Atlantic season's first hurricane on Wednesday night, the news report added.
Chevron (CVX) has begun shut-in procedures for production at four Gulf of America facilities and is evacuating workers as Isaias approaches, the company said.
Front-month US West Texas Intermediate crude oil contract surged 4.8% to $92.48 per barrel, and global benchmark Brent soared 5.2% to $105.42 per barrel.
US initial jobless claims fell sequentially to 197,000 in the week ended Oct. 3 from an upwardly revised 199,000, compared with expectations for 200,000 in a Bloomberg-compiled survey. The four-week moving average fell to 198,000 after decreasing to 200,500 in the previous week, marking a fifth straight weekly decline.
Most Treasury yields rose, with the two-year up 2.5 basis points to 4.79%. The 10- and 30-year yields traded close to their highest levels since 2002.
The probability of the Federal Reserve keeping interest rates unchanged in October stood at 81% on Thursday, according to the CME's FedWatch tool, following the release of its September meeting minutes Wednesday. However, the market sees a 70% likelihood that the Fed will raise its target rate by 25 basis points in December and assigns a 45% probability of another move higher of the same magnitude in March to bring inflation back to its 2% target.