GLOBAL MARKETS-US, world equities flutter amid doubts over Iran peace talks as ceasefire expiration looms

(Updates to US market open)

* Markets optimistic over possible Iran-US talks, but ceasefire remains fragile

* Fed nominee Warsh attends Senate Banking Committee hearing

* US retail sales data breezes past analyst expectations

By Stephen Culp

NEW YORK, April 21 (Reuters) - Wall Street stocks turned mostly lower, while global equities dipped as optimism over peace talks faded and the U.S.-Iran ceasefire expiration loomed.

Two of the three major U.S. stock indexes slipped, while gold dropped and U.S. crude advanced. The U.S. military said it had seized a tanker linked to Iran in international waters in an apparent action to enforce a blockade as the clock ticked toward the ceasefire's expiry. Washington expressed confidence that peace talks with Iran would proceed in Pakistan. But Pakistan is awaiting a formal confirmation from Iran that it will send a delegation to Islamabad for a second round of peace talks.

"It's become very clear that the Trump administration is looking for an off-ramp and will negotiate in a manner that they can claim a win," said Oliver Pursche, senior vice president at Wealthspire Advisors in New York. "U.S. investors and global investors are holding their breath, but leaning to a positive outcome when it comes to Iran."

EYES ON AI Amazon said on Monday it will invest up to $25 billion in Anthropic, reviving the fervor over artificial intelligence-related stocks.

As the first-quarter reporting season heats up, investors will scrutinize AI stocks for signs that massive expenditures on the nascent technology are starting to pay off. Analysts expect aggregate year-on-year tech earnings growth of 46.4%, according to LSEG data. A report from the Commerce Department showed U.S. retail sales were more robust than analysts expected in March, but much of the upside surprise was driven by a 15.5% surge in gasoline station receipts due to price spikes related to the U.S.-Israeli war with Iran.

Kevin Warsh, U.S. President Donald Trump's pick to succeed Jerome Powell as Federal Reserve chair, appeared before the Senate Banking Committee in the next step toward confirmation. In his opening statement, the former Fed governor pledged to make interest rate decisions "strictly independent" of politics. The Dow Jones Industrial Average fell 34.99 points, or 0.07%, to 49,407.09, the S&P 500 lost 10.22 points, or 0.15%, to 7,098.71 and the Nasdaq Composite rose 13.90 points, or 0.05%, to 24,415.85.

EUROPEAN SHARES DIP, GLOBAL STOCKS RISE

European shares were lower amid restrained risk appetite ahead of the ceasefire deadline. MSCI's gauge of stocks across the globe fell 1.61 points, or 0.15%, to 1,070.38. The pan-European STOXX 600 index fell 0.77%, while Europe's broad FTSEurofirst 300 index fell 19.99 points, or 0.81%. Emerging market stocks rose 14.66 points, or 0.92%, to 1,615.04. MSCI's broadest index of Asia-Pacific shares outside Japan closed higher by 1.04%, to 826.86, while Japan's Nikkei rose 524.28 points, or 0.89%, to 59,349.17. The U.S. dollar edged higher on optimism over Iran war negotiations, and after retail sales data signaled economic strength. The dollar index, which measures the greenback against a basket of currencies including the yen and the euro, rose 0.19% to 98.26, with the euro down 0.25% at $1.1757. Against the Japanese yen, the dollar strengthened 0.33% to 159.31. The yield on benchmark U.S. 10-year notes rose 4.2 basis points to 4.292%, from 4.25% late on Monday. The 30-year bond yield rose 2.2 basis points to 4.903% from 4.881% late on Monday. The 2-year note yield, which typically moves in step with interest rate expectations for the Federal Reserve, rose 5.9 basis points to 3.775%, from 3.716% late on Monday.

Oil prices reversed an earlier dip as traffic in the Strait of Hormuz remained halted. U.S. crude rose 3.16% to $92.44 a barrel and Brent rose to $97.02 per barrel, up 1.64%.

Gold prices dropped as the dollar firmed, as investors looked to tentative U.S.-Iran talks and Warsh's Senate confirmation hearing. Spot gold fell 1.4% to $4,752.02 an ounce.

(Reporting by Stephen Culp; Additional reporting by Amanda Cooper in London and Gregor Stuart Hunter in Tokyo; Editing by Rod Nickel)