(Updates with index/price moves, macroeconomic data, and geopolitical news from the first paragraph.)

US equity indexes rose as crude oil prices and government bond yields fluctuated.

The Nasdaq Composite rose 0.4% to 26,215.4, the S&P 500 climbed 0.5% to 7,667.3, and the Dow Jones Industrial Average advanced 0.4% to 52,963.7 after midday Wednesday.

Iranians and their Arab neighbours feared a return of war on Wednesday after the biggest exchange of fire between Tehran and Washington since July, with US forces striking Iran's southern coast and Iran firing at American bases across the region, Reuters reported. The Iran Revolutionary Guards Corps said that two oil tankers exploded after hitting a mine and are now on fire, Al Jazeera, a Middle Eastern broadcaster, reported.

The front-month US West Texas Intermediate crude oil contract added 0.6% to $90.79 per barrel, and global benchmark North Sea Brent climbed 0.9% to $95.53 per barrel. Both crude types were down by more than 0.5% earlier in the session.

Most US Treasury yields traded mixed, albeit moderately. The 10-year yield edged up by less than one basis point to 4.8% after trading slightly lower earlier in the session. The two-year yield slipped less than one basis point to 4.39%.

Meanwhile, ADP's monthly measure of private payrolls showed a 38,000 increase in August, below a 47,000 gain expected in a Bloomberg-compiled survey, following a 46,000 increase in July. Service-providing jobs climbed 48,000, with education and health services jobs up 45,000, while manufacturing sector jobs contracted 17,000.

Dell Technologies (DELL) jumped 10%, the top gainer on the S&P 500, after the company reported higher fiscal Q2 non-GAAP adjusted earnings and revenue, and raised its fiscal 2027 guidance.