Updates after market open

By Medha Singh and Twesha Dikshit

June 1 (Reuters) - Wall Street's main indexes hovered near record highs on Monday as investors weighed Nvidia's latest artificial intelligence push against mounting skepticism that a deal to end the three-month-old U.S.-Iran war could be reached soon.

Nvidia NVDA.O rose 4% after unveiling a new chip that puts AI capabilities directly into laptops and desktop computers.

The chip is the result of a three-year partnership with Microsoft MSFT.O to "reinvent the PC" for the AI era, Nvidia CEO Jensen Huang said. Microsoft shares added 2.5%.

The S&P 500 tech index .SPLRCT gained 1.5%.

The reaction in semiconductor stocks was mixed. Qualcomm QCOM.O tumbled 6%, while PC chipmakers AMD AMD.O and Intel fell 3.1% and 4.4%, respectively. Micron MU.O rose 5.7% to $1,022, topping the $1,000 mark for the first time. Its shares have soared nearly 90% in May.

"Nvidia might expand the market, but most of its gains will come at the expense of the incumbents," said Brian Jacobsen, chief economic strategist at Annex Wealth Management.

Memory makers such as Micron stood to benefit because their chips complement the processors that go into new computers, and an AI-driven refresh cycle could lift the premium end of the PC market, he said.

The mood was somber, with oil prices climbing 5% after Tasnim news agency reported that Iran's negotiating team was stopping talks with the U.S. over attacks on Lebanon.

Nine of the 11 main S&P 500 sectors were in the red, with consumer discretionary .SPLRCD leading declines with a 2% fall.

At 09:40 a.m. the Dow Jones Industrial Average .DJI lost 177.00 points, or 0.35%, to 50,855.46, the S&P 500 .SPX rose 1.82 points, or 0.02%, to 7,581.88, and the Nasdaq Composite .IXIC gained 39.52 points, or 0.15%, to 27,012.14.

Software stocks also rebounded from the heavy selling earlier this year on AI disruption fears. ServiceNow NOW.N and IBM IBM.N rose 10.7% and 6%, respectively. The software services index .SPLRCIS advanced 3% after erasing all losses from January-end.

Cadence Design Systems CDNS.O added 3% after launching an Nvidia-powered AI agent for chip design.

Wall Street's main indexes ended May at record highs, buoyed by hopes of an eventual end to the war and blowout first-quarter earnings. Optimism around AI has helped boost U.S. equities, but concerns over the economic impact from the hostilities remain.

Investors will turn to Friday's jobs report ahead of Kevin Warsh's debut policy meeting as chairman of the U.S. Federal Reserve this month, amid fears of rising inflation linked to the Iran war that could upend the stock market rally.

"Passing the baton from one chair to the next isn't always a smooth process. If the Strait of Hormuz doesn't more fully open before the next Fed meeting, it's almost certain that the Fed's policy statement will become more hawkish," Jacobsen said.

Traders have priced in a near 70% chance of a quarter-point rate hike before the end of the year.

Broadcom AVGO.O earnings on Wednesday will also be in focus after a strong results forecast last week from AI-server maker Dell DELL.N.

Among other company movers, Taylor Morrison Home Corp TMHC.N jumped 22% after Berkshire Hathaway BRKa.N agreed to buy the homebuilder for $6.8 billion in cash.

Declining issues outnumbered advancers by a 1.65-to-1 ratio on the NYSE and by a 1.45-to-1 ratio on the Nasdaq.

The S&P 500 posted 17 new 52-week highs and 10 new lows, while the Nasdaq Composite recorded 47 new highs and 29 new lows.