US STOCKS-S&P 500 inches lower as Middle East tensions outweigh tech gains

Updates for market open

By Avinash P and Purvi Agarwal

Aug 17 (Reuters) - The S&P 500 was muted on Monday as markets weighed tensions between the U.S. and Iran, while the report of a strong revenue forecast from AI lab Anthropic lifted some technology stocks.

Tehran will escalate tensions in the Strait of Hormuz and the wider region if diplomacy with the United States fails, a senior Iranian official told Reuters, pointing to an Iranian policy shift relying on offense rather than defense.

Brent crude futures LCOc1 gained about 0.4%, with the S&P 500 energy index .SPNY 0.2% higher.

"(Investors) were telling themselves wars always come to an end. I don't think anyone was pricing in the fact that this could still be going as we approach the end of the summer," said David Morrison, senior market analyst at Trade Nation.

Meanwhile, Reuters reported on Friday that Anthropic, which is preparing for its IPO, forecast 2028 revenue of roughly $190 billion to $200 billion, according to two people familiar with the company's financials.

Chipmakers took the lead, with Micron Technology MU.O and Sandisk SNDK.O rising 4.5% and 6.7%, respectively.

Technology stocks on the S&P 500 .SPLRCT rose 0.1%, limiting broader declines and keeping the tech-heavy Nasdaq flat.

Markets will keep a close eye next week on results from chipmaker Nvidia NVDA.O, the most valuable company in the world, for signs on whether the tech-driven momentum can last. Its shares rose 0.2% in early trading.

Danni Hewson, head of financial analysis at AJ Bell, said more clarity on AI investments and the source of returns was allaying immediate fears of a "potential AI boom then bust".

At 09:40 a.m. ET, the Dow Jones Industrial Average .DJI fell 164.46 points, or 0.31%, to 53,567.95, the S&P 500 .SPX lost 10.71 points, or 0.14%, to 7,775.01, and the Nasdaq Composite .IXIC shed 2.43 points, or 0.01%, to 26,726.73.

Declines in UnitedHealth UNH.N and McDonald's MCD.N weighed on the Dow.

Concerns over the payoff from AI investments have battered chip stocks recently, but robust quarterly results and forecasts signaling resilient demand have brought the tech-heavy Nasdaq .IXIC closer to record highs.

The S&P 500 .SPX closed at a record peak on Thursday after a batch of soft inflation data helped traders dial back the odds of an interest-rate hike by the U.S. Federal Reserve at its September meeting.

Traders are pricing in a nearly 31% chance the Fed will raise rates by 25 basis points next month, sharply lower than the near-even chances of a hike versus a hold a week ago, according to CME's FedWatch tool.

Still, Wells Fargo Investment Institute changed its Fed call and expects a 25-basis-point increase to rates this year, versus no change anticipated earlier.

Quarterly results from retail bellwether Walmart WMT.O and home improvement retailer Home Depot HD.N, among the few names left to report in the current earnings season, will be watched this week.

In other movers, U.S.-listed shares of Vista VISTAA.MX, VIST.N gained 5.3% after Peter Thiel bought a 1% stake in the Latin American oil company.

Declining issues outnumbered advancers by a 1.55-to-1 ratio on the NYSE and by a 1.43-to-1 ratio on the Nasdaq.

The S&P 500 posted eight new 52-week highs and no new lows, while the Nasdaq Composite recorded 29 new highs and 34 new lows.

(Reporting by Avinash P and Purvi Agarwal in Bengaluru; Editing by Pooja Desai)

((Avinash.P@thomsonreuters.com;))