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* Futures down: Dow 0.16%, S&P 500 0.18%, Nasdaq 0.51%

April 28 (Reuters) - Futures tracking the benchmark S&P

500 and the tech-heavy Nasdaq 100 indexes fell early on Tuesday

as concerns mounted that the U.S.-Iran impasse could keep oil

prices elevated for longer.

At 5:36 a.m. ET, Dow E-minis slipped 11 points, or

0.16%, S&P 500 E-minis were down 12.75 points, or 0.18%,

and Nasdaq 100 E-minis fell 141.25 points, or 0.51%.

A U.S. official said President Donald Trump was unhappy with

the latest Iranian proposal ​on resolving the conflict in the

Middle East, pouring cold water on hopes for a resolution that

had sent the S&P 500, the Nasdaq 100 and the

Nasdaq Composite to record highs in recent days.

The pullback underscores how strongly the war is shaping

market sentiment even during the busiest week of the U.S.

corporate earnings season this quarter.

Oil prices are 54% higher than pre-war levels as the crucial

shipping route through the Strait of Hormuz remains disrupted.

"The divergence between equity market optimism and the more

cautious signals from bond and oil markets reinforces the view

that geopolitical developments remain an active and important

variable in risk management," said Ameriprise Financial's Chief

Market Strategist Anthony Saglimbene.

Separately, the Wall Street Journal reported that OpenAI had

missed internal targets for weekly users and revenue.

Shares of Oracle, whose reliance on OpenAI for its

cloud computing ambitions has been under scrutiny, fell 4.6% in

the premarket session.

Chip stocks also dropped, with Nvidia ( NVDA ), AMD

and Arm Holdings down 1.2%, 3.2% and 6.8%, respectively.

Investors will parse earnings from a bunch of corporate

giants on Tuesday, including UPS, Coca-Cola and

General Motors ( GM ).

UPS was 0.7% higher, while Coca-Cola and General Motors ( GM ) rose

nearly 1% each ahead of the results.

(Reporting by Niket Nishant in Bengaluru; Editing by Devika

Syamnath)