US equity indexes fell in midday trading on Monday as oil prices and Treasury yields climbed after US President Donald Trump rejected Iran's settlement proposal.

Trump expects US negotiators to engage in more talks with Iran this week, and said that over 20 million barrels transited the Strait of Hormuz over the weekend, Axios reported Sunday, citing a conversation with the president.

The Nasdaq Composite fell 0.6% to 26,896.3. The Dow Jones Industrial Average fell 0.5% to 51,576, while the S&P 500 declined by 0.5% to 7,701.6. Communication services and consumer discretionary sectors led decliners, while the energy sector led the gainers.

The US West Texas Intermediate crude oil contract rose 2.3% to $94.53 per barrel.

The majority of US Treasury yields rose intraday, with the 10-year yield edging up 6.6 basis points to 5.247% and the 30-year rate 6.3 basis points to 5.565%.

In economic news, the Dallas Fed's monthly manufacturing index declined to 9.8 in September from 11.6 in the month prior, compared with Bloomberg-survey expectations for a larger decrease to 7.8.

The reading for the company outlook fell to 8.7 from 19.2 in August.

In company news, Nvidia's (NVDA) board approved an additional $150 billion under its existing share repurchase program, increasing the total remaining authorization to $235 billion, the company said Monday, adding that it expects to carry out the share buybacks under the remaining program through fiscal 2028. Nvidia shares were up 3%.