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

US equity indexes declined as an Iran-backed militia group's attack on Saudi Arabian energy sites pushed crude oil prices higher.

The Nasdaq Composite declined 0.2% to 26,455.1, the S&P 500 retreated 0.4% to 7,688.2, and the Dow Jones Industrial Average dropped 1.1% to 52,839.5 after midday Tuesday.

Energy and utilities were among a trio of gainers intraday. Healthcare and financials led decliners.

Yemen's Tehran-backed Houthis attacked energy facilities and cities in US ally Saudi Arabia on Tuesday, wounding more than 70 people and underscoring the risk of the Iran conflict escalating into a wider regional war, Reuters reported. Saudi Arabia said the attacks stopped operations at several energy facilities in the kingdom's south, Bloomberg reported, while noting a pick-up in buying by China, the world's largest importer.

The front-month US West Texas Intermediate crude oil contract climbed 0.7% to $92.11 per barrel, and global benchmark North Sea Brent advanced 0.3% to $97.27 per barrel, off session highs of more than 1% each.

"As we ponder a prolonged conflict, our expectations increasingly shift to a slower recovery in Middle East oil supply," Peter Taylor, head of commodity strategy at Macquarie, said in a note. "In this environment, we would anticipate deficits persisting through [year-end 2026], with the market approximately balanced in 2027."

US Treasury yields rose, with the two-year up 1.5 basis points to 4.39% and the 10-year higher by 1.4 basis points to 4.80%.

Gold futures fell 1.1% to $4,428.1.

In company news, Intel (INTC) is expected to raise personal computer central processing unit prices by another 10% in early October, Digitimes reported, citing supply chain sources. Intel shares jumped 9%, among the top gainers on the S&P 500 and the Nasdaq.

Palantir Technologies (PLTR) and Nebius Group (NBIS) agreed on a strategic partnership that will give Palantir commercial customers access to Nebius' artificial intelligence-native compute infrastructure and cloud platform, the companies said Tuesday. Nebius surged 10%, among the biggest Nasdaq outperformers.

Novartis (NVS) sank 13% after the company said its phase 3 Harbor study evaluating delpacibart etedesiran in patients with myotonic dystrophy type 1 failed to meet its primary endpoint of video hand opening time.

Canadian tariffs announced after trade talks with the US collapsed last month took effect on Tuesday and range from 15% to 50%, impacting hundreds of US products, including dairy, agricultural equipment, paper, household appliances and electronics.