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

US equity indexes fell, while both government bond yields and crude oil rose after midday Thursday.

The Dow Jones Industrial Average declined 0.7% to 53,971.2, with the S&P 500 down 0.3% to 7,703.1 and the Nasdaq Composite lower by 0.2% to 26,308.7.

Among companies with a market capitalization of more than $200 billion, four of the top five belonged to either the semiconductor or the semiconductor equipment and materials industries. Arm (ARM) was the biggest outperformer in this category.

Energy was the sole gainer in midday trading.

Iran has made a concerted diplomatic push with Gulf states, warning them explicitly that Tehran will hit their oil, power and water plants unless they convince President Donald Trump to end US strikes on Iran, Reuters reported Thursday.

Iran and Oman are close to finalizing a proposed framework for commercial shipping through the Strait of Hormuz, Tehran's deputy foreign minister said, according to a CNN report Thursday. However, the agreement would not automatically reopen the waterway, he warned, according to the news report. The deal would give Tehran control over ships entering the Gulf through the Strait of Hormuz, a senior Iranian source and two regional officials told Reuters on Wednesday.

The front-month US West Texas Intermediate crude oil contract climbed 1.9% to $76.61 a barrel, and global benchmark North Sea Brent jumped 2.2% to $81.20 a barrel.

US Treasury yields rose, with the 10-year yield up 3.1 basis points to 4.65% and the two-year higher by 4.8 basis points to 4.23%.