US equity indexes ground higher amid a slump in crude oil prices as investors parsed ongoing talks to end the war against Iran and as tech mega-cap names consolidated.

The Dow Jones Industrial Average traded up 0.4% to 50,644.28 on Wednesday. The Nasdaq Composite edged up less than 0.1% to 26,674.74, and the S&P 500 climbed less than 0.1% to 7,520.36. Both the Nasdaq and the S&P 500 were declining earlier in the day.

Consumer discretionary, consumer staples, and communication services topped the gainers at the close. Energy and financials led the decliners. Among the stocks with a market capitalization of more than $200 billion, seven of the ten worst performers were technology companies, led by Qualcomm (QCOM) and Arm (ARM).

The memorandum of understanding being negotiated between Tehran and Washington will call for US forces to withdraw from Iran's vicinity and lift the blockade of Iranian ports in return for reopening the Strait of Hormuz to pre-war levels, CNN reported, citing Iranian state television. The US denied claims that maritime traffic through the Strait of Hormuz could return to normal within a month of the Iran deal, Bloomberg reported.

During an ongoing Cabinet meeting on Wednesday, President Donald Trump said he won't be rushed into a deal, warning that Iran's efforts to outlast him won't work because he doesn't "care about the midterms," CNN reported.

"Iran is very much intent; they want very much to make a deal. So far, they haven't gotten there ... We're not satisfied with it, but we will be. Either that, or we'll have to just finish the job," Trump said, without elaborating, according to a report from Reuters. "The deal has got to be perfect," he added, insisting that no single country would have control over Hormuz.

West Texas Intermediate crude oil futures sank 4.8% to $89.35, and Brent crude futures slumped 4.7% to $94.91.

Most US Treasury yields fell, with the 10-year down one basis point to 4.48%. The two-year slipped 1.5 basis points to 4.04%.

In economic news, Redbook US same-store sales jumped 9% from a year earlier in the week ended May 23 after an 8.1% gain in the prior week. "Demand for a wide variety of summer, home and garden, and seasonal apparel products was the main focus for most consumers," Redbook said.

The Dallas Federal Reserve's monthly general business services index improved to minus 7.7 in May from minus 9.9 in April, versus the minus 6.0 anticipated.

The Richmond Fed's monthly manufacturing index rose to 13 in May from 3 in April, more than the 4 estimate in a Bloomberg-compiled survey.

In company news, Boston Scientific (BSX) shares sank 12%, the worst performer on the S&P 500, after Chief Executive Mike Mahoney said at an industry conference that this year has been "a bit more of a challenge" than anticipated. Stifel adjusted its price target on Boston Scientific shares to $75 from $85 while maintaining its buy rating, a move mirrored by Goldman Sachs.

Zscaler (ZS) stock plunged 32%, the steepest decline in the Nasdaq, after the company issued a fiscal Q4 revenue outlook that missed analysts' expectations. Zscaler stock remains in the penalty box until further evidence of traction emerges in the security operations business, new sales leader roles are filled, and the operating structure improves, Morgan Stanley said in a research report.

In precious metals, gold futures dropped 1.1% to $4,452.1, and silver futures slumped 2.3% to $74.87.