(Updates to US market open, changes dateline, byline)

* Trump unhappy with latest Iranian proposal, official

says

* Tech stocks slip on AI spending boom concerns

* UAE sets date for leaving OPEC, OPEC+

By Rodrigo Campos

NEW YORK, April 28 (Reuters) - Stocks fell and oil

prices rose on Tuesday as investors assessed the stalemate in

the Iran conflict and news the United Arab Emirates was cutting

ties with OPEC, while concerns the AI boom was losing momentum

weighed on equity markets.

U.S. bond prices also slid, with yields up on concern over

the effect of high energy prices on inflation.

U.S. President Donald Trump is unhappy with the latest

Iranian proposal ​on resolving the two-month war, a U.S.

official said, dampening hopes for resolution of a conflict that

has disrupted energy supplies, fuelled inflation, and killed

‌thousands. The two-month-long conflict is at an impasse and

energy and other supplies are still failing to cross through the

critical Strait of Hormuz.

The UAE said on Tuesday it was quitting OPEC and OPEC+,

dealing a blow to the oil exporting groups and their de facto

leader Saudi Arabia, at a time when the Middle East conflict has

caused a historic energy shock. Oil prices briefly pared gains

on the news, but Brent was last hovering near a three-week high

while WTI broke through $100 per barrel for the first time since

April 13.

"The UAE leaving shows how tough it can be to keep a cartel

together during tough times," said Brian Jacobsen, chief

economic strategist at Annex Wealth Management. "The UAE is

OPEC's third largest producer and the quota it has is well below

its capacity."

He said even if the immediate reaction was muted,

"longer-term it gives OPEC a lot less sway over the markets."

U.S. crude was up 3.57% at $99.76 a barrel and Brent

rose to $111.03 per barrel, up 2.59% on the day.

EARNINGS SEASON AND AI IN FOCUS

The tech-focused Nasdaq Composite fell more than 1% as

investors questioned whether the so-far-unstoppable artificial

intelligence boom can continue to deliver meaningful returns for

investors. The Wall Street Journal reported that AI heavyweight

OpenAI had missed internal targets for weekly users and revenue,

raising concerns over the ChatGPT parent's ability to support

its massive spending on data centers.

"That's putting pressure on the Nasdaq and on the S&P

because tech and communication services make up about 40% of the

benchmark," said Art Hogan, chief ​market strategist at B. Riley

Wealth.

"If OpenAI is seeing some degradation, that will shuffle the

deck a bit in terms of what the leadership looks like."

The Dow Jones Industrial Average fell 29.19 points,

or 0.06%, to 49,138.60, the S&P 500 fell 50.97 points, or

0.71%, to 7,122.94 and the Nasdaq Composite fell 302.74

points, or 1.22%, to 24,584.36.

Tech stocks related to OpenAI, such as Oracle and

CoreWeave ( CRWV ), fell over 4% each.

MSCI's gauge of stocks across the globe fell

8.04 points, or 0.75%, to 1,066.96.

The pan-European STOXX 600 index fell 0.57%, the

emerging market stocks gauge was down 0.88% at

1,615.58 and MSCI's broadest index of Asia-Pacific shares

outside Japan closed lower by 0.78%. Japan's

Nikkei index fell 1% after hitting a record high on

Monday.

Investors are also focusing this week on earnings from U.S.

tech giants Microsoft ( MSFT ), Alphabet, Amazon ( AMZN )

, Meta Platforms ( META ) and Apple ( AAPL ) that will

further test the AI-driven rally.

Higher oil prices continued to weigh on inflation

expectations. The 2-year Treasury note yield, which

typically moves in step with interest rate expectations for the

Federal Reserve, rose 3.9 basis points to 3.844%, from 3.805%

late on Monday.

The yield on benchmark U.S. 10-year notes rose 3

basis points to 4.366%, from 4.336% late on Monday, while the

30-year bond yield rose 2.2 basis points to 4.9636%

from 4.942%.

Elsewhere, the dollar index - which measures the

greenback against a basket of currencies including the yen and

the euro - climbed 0.4%. The British pound fell 0.5% against the

dollar and the euro dipped 0.35% .

The dollar has been one of the few safe-haven assets during the

Iran conflict, although it has given up many of its March gains

in the last few weeks.

"The twists and turns of U.S.-Iran peace negotiations

continue to buffet markets," Nick Rees, head of macro research

at Monex Europe, said, adding doubts over the progress of peace

talks had pushed the dollar higher.

BANK OF JAPAN SPLIT ON RATES

The BOJ left short-term rates unchanged on Tuesday at 0.75%,

in the first of several central bank meetings this week that

could provide evidence of the conflict's economic impact.

The yen initially strengthened on the view that a

rate hike was now in play, but was last around 0.2% lower at

159.74 per dollar. A breach beyond the 160-per-dollar threshold

has markets on alert that Tokyo might step in to support the

currency.

The U.S. Federal Reserve, the Bank of England and the European

Central Bank are due to announce decisions later this week.

All are expected to keep rates unchanged but market

attention will be on comments from policymakers on pricing

pressure.

(Reporting by Rodrigo Campos in New York; Editing by Emelia

Sithole-Matarise)