* US stocks last down slightly
* Iran supreme leader says uranium should stay in Iran
* Stance could threaten U.S.-Iran peace talks
* Nvidia stock slips despite earnings beating forecasts (Updates to midday US eastern time)
NEW YORK/LONDON, May 21 (Reuters) - Treasury yields and oil prices rose while U.S. stocks dipped on Thursday after Reuters reported Iran's supreme leader has issued a directive that the country's near-weapons-grade uranium should not be sent abroad, a hard stance against one of the main U.S. demands.
Also weighing on U.S. stocks were shares of Nvidia, the world's biggest company by market capitalization. Nvidia was down 1.6% in choppy early trading despite the company's earnings beating Wall Street expectations.
Nvidia late on Wednesday forecast second-quarter earnings of $91 billion and announced an $80 billion share repurchase programme.
Iran Supreme Leader Ayatollah Mojtaba Khamenei's order could complicate talks on ending the U.S.-Israeli war on Iran, potentially making the conflict, which has sent energy prices soaring, drag on.
U.S. President Donald Trump has assured Israel that Iran's stockpile of highly enriched uranium will be removed and that any peace deal must include the demand, Israeli officials have told Reuters.
Investors were also watching developments in Turkey. Trading on Turkey's stock market was temporarily halted after sharp falls and the government's bonds slid after one of the country's top courts dealt the latest blow to the main political opposition party. The court's move annulled the 2023 congress of the main opposition Republican People's Party in which its current chairman, Ozgur Ozel, was elected.
The U.S.-traded iShares MSCI Turkey exchange-traded fund was last down 8.8%.
In the Treasury market, the yield on benchmark U.S. 10-year notes rose 3.9 basis points to 4.609%, from 4.57% late on Wednesday. Oil prices also were higher. U.S. crude rose 3.22% to $101.42 a barrel and Brent rose to $107.71 per barrel, up 2.54% on the day.
Stocks on Wall Street were slightly lower as investors weighed the latest news on Iran.
"When you look at the normal economic environment surrounding this market, you would expect (stocks) to be lower, but if you believe the war will come to an end soon - that we're at a temporary high on energy prices, it does push you to look more not just at the underlying earnings that have been good but also the earnings potential that comes from AI," said Rick Meckler, partner at Cherry Lane Investments.
SpaceX unveiled its IPO filing late on Wednesday, giving the market its first glimpse into how much billionaire Elon Musk is spending on AI as he bets on transforming the rocket maker into a broader AI-led business.
The Dow Jones Industrial Average fell 70.95 points, or 0.15%, to 49,936.02; the S&P 500 fell 27.51 points, or 0.37%, to 7,405.46; and the Nasdaq Composite fell 144.51 points, or 0.55%, to 26,127.03.
MSCI's gauge of stocks across the globe rose 1.62 points, or 0.15%, to 1,103.27.
The pan-European STOXX 600 index rose 0.25%.
The dollar rose to a six-week high after the Iran report.
The dollar index, which measures the greenback against a basket of currencies including the yen and the euro, rose 0.26% to 99.39, with the euro down 0.3% at $1.1592. Against the Japanese yen, the dollar strengthened 0.18% to 159.19.
Spot gold fell 0.82% to $4,506.11 an ounce. (Reporting by Caroline Valetkevitch in New York and Harry Robertson in London; Additional reporting by Gregor Stuart Hunter in Singapore; Editing by Alex Richardson, Chizu Nomiyama and Chris Reese)
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