(Updated to reflect US market open)

* Nasdaq down 1%, S&P slips 0.3%, Dow flat

* Brent crude up 1.9% after US-Iran peace talks appeared to

stall

* Samsung sees 19-fold increase in April-June operating

profit

By Amanda Cooper and Pete Schroeder

LONDON/WASHINGTON, July 7 (Reuters) - Global stocks fell on

Tuesday as technology shares slid despite blockbuster results

from Samsung Electronics ( SSNLF ), with investors remaining concerned

about the sustainability of the AI-driven rally, while oil

prices rose on renewed Middle East tensions.

The tech-heavy Nasdaq Composite was down 0.97% in

early trading Tuesday, while the S&P 500 slipped 0.32%. The Dow

Jones Industrial Average was flat.

Stocks took a step backwards despite Samsung Electronics ( SSNLF )

forecasting a 19-fold jump in April-June operating

profit to 89.4 trillion won ($58.4 billion), a third straight

quarter of record operating profit for the world's largest

memory-chipmaker.

Rather than reassuring investors, the results triggered

heavy selling in Samsung and rival SK Hynix shares, weighing on

South Korea's Kospi and other technology-heavy Asian

markets. Investors have increasingly questioned whether profit

growth linked to artificial intelligence can be sustained if

supply bottlenecks in key components such as memory chips ease.

"This is a record for Samsung, but rather than placate the

markets, these strong results have led to fears that the AI chip

sales boom cannot be sustained," Kathleen Brooks, research

director at XTB, said.

Further weighing on markets was a Reuters report that

Chinese startup DeepSeek was developing its own AI chip, which

could reduce its reliance on other major chipmakers to train and

run its AI models.

SK Hynix is due to join the Nasdaq this week in a $28

billion listing, one of the world's largest new share sales, as

the chipmaker seeks to capitalise on the AI boom.

In Europe, where exposure to volatile AI-linked stocks is

more limited, the STOXX 600 slipped 0.16%, as losses in

semiconductor and tech stocks offset gains in oil and gas

shares. Energy stocks got a lift from crude prices gaining on

the back of signs that U.S.-Iran peace talks were losing

momentum.

MSCI's gauge of stocks across the globe was

down 0.36%.

Adding to market concerns, Iran's Revolutionary Guards fired

at least two missiles at commercial ships transiting the Strait

of Hormuz on Monday, Axios reported, citing two U.S. officials.

The ships suffered significant damage, but there were no

casualties, the report said.

Brent crude futures rose about 1.9% to $73.37 a barrel.

NATO MEETING SET TO START IN TURKEY

U.S. President Donald Trump, who has pressed Europe to boost

defence spending and clashed with European leaders over the Iran

war and Greenland, is due to attend a NATO meeting in Turkey

beginning on Tuesday.

Trump said on Monday the U.S. would either reach a deal with

Iran or "finish the job," renewing his threat of military action

as Tehran projects defiance following the funeral of Supreme

Leader Ayatollah Ali Khamenei.

In currency markets, the dollar index, which tracks

the U.S. currency against six others, was little changed at

100.87.

The yen clawed above 40-year lows to trade a touch

stronger on the day at 161.9 to the dollar. Traders were alert

for intervention given signs of a possible shift in strategy by

Japanese authorities.

The yield on benchmark U.S. 10-year notes was up

2.4 basis points at 4.503% ahead of the release on Wednesday of

the minutes of the Federal Open Market Committee's latest

meeting. These may give investors more of a steer on how new

Federal Reserve chair Kevin Warsh is approaching monetary

policy.

(Additional reporting by Satoshi Sugiyama in Tokyo; Editing by

Mark Potter and Kevin Liffey)