NEW YORK: US stocks fell on Wednesday ahead of a quarterly report from Nvidia, Wall Street's centre-piece event of the week that could shatter or add fresh fuel to a rally driven by optimism around artificial intelligence.

Shares of the dominant seller of AI processors, due to report after the closing bell, dipped 2.1%, trimming their gain so far this year to 154%.

Following several blowout quarterly reports, Nvidia is viewed as the biggest winner so far from AI technology. Its latest results follow concerns about increases in already-hefty spending by Microsoft, Alphabet and other major players in the race to dominate emerging AI technology.

"It's been the poster child for the AI boom and it's really led the charge, so it would be hard for the market to move on in spite of a disappointment from Nvidia," warned Keith Buchanan, senior portfolio manager at GLOBALT Investments in Atlanta.

"Nobody has their arms around how long Nvidia can continue to surprise on the upside, but, naturally, it can't last forever," Buchanan added.

Options pricing shows traders anticipate a move of around 9.8% in Nvidia's shares on Thursday, a day after it reports its results, data from analytics firm ORATS showed.

Other chip stocks also dipped, with Broadcom and Advanced Micro Devices each losing more than 2%.

Google-owner Alphabet, Microsoft and Amazon each lost about 1%.

The S&P 500 declined 0.60% to end the session at 5,592.18 points.

The Nasdaq declined 1.12% to 17,556.03 points, while the Dow Jones Industrial Average declined 0.39% to 41,091.42 points.

Of the 11 S&P 500 sector indexes, eight declined, led lower by information technology, down 1.3%, followed by a 1.05% loss in consumer discretionary.

Investors widely expect the US Federal Reserve will lower interest rates at its September meeting after Fed chair Jerome Powell's support for imminent policy adjustment last week sparked broad-based market gains.

The CME Group's FedWatch Tool currently sees a 64% chance of a 25-basis point reduction and a 37% chance of a 50-bps cut.

The Personal Consumption Expenditure report for July, due on Friday, may provide further insight into the central bank's likely rate-cut trajectory.

Super Micro Computer tumbled 19% after the AI server maker said it would delay the filing of its annual report for the fiscal year ended June 30, a day after Hindenburg Research disclosed a short position in the company.

The market value of billionaire Warren Buffett's Berkshire Hathaway surpassed US$1 trillion for the first time. Its class B stock rose about 0.9%.

Declining stocks outnumbered rising ones within the S&P 500 by a 1.3-to-one ratio.

Volume on US exchanges was relatively light, with 9.9 billion shares traded, compared to an average of 11.7 billion shares over the previous 20 sessions.

 - Reuters