* Indexes up: Dow 0.72%, S&P 500 0.65%, Nasdaq 0.76%

* Trump declares Iran ceasefire extension

* GE Vernova ( GEV ), Boeing ( BA ) and Boston Scientific ( BSX ) rise after

results

(Updates after markets open)

By Avinash P and Niket Nishant

April 22 (Reuters) - Wall Street's main indexes edged

higher on Wednesday after U.S. President Donald Trump extended

the ceasefire with Iran, even as uncertainty remained over

whether Tehran and U.S. ally Israel would honor the truce.

Trump said the indefinite extension of the ceasefire

followed a request by Pakistani mediators. However, the U.S.

Navy's blockade of Iranian ports remained in effect, and Iran

seized two ships in the Strait of Hormuz.

The opening of the waterway, responsible for about 20% of

global oil supply, remains a major unknown for investors and has

been one of the sticking points in the negotiations.

The bullish sentiment despite the uncertainty points to a

market desperate to cling to good news, and reflects investor

belief that despite setbacks, the war will be settled at the

negotiating table instead of the battlefield.

"At some stage, this rally is going to come to a halt. But I

don't think that the majority of investors feel that way at

all," said David Morrison, senior market analyst at Trade

Nation.

At 09:50 a.m. ET, the Dow Jones Industrial Average

rose 343.83 points, or 0.72%, to 49,504.58, the S&P 500

gained 45.98 points, or 0.65%, to 7,109.99 and the Nasdaq

Composite gained 185.28 points, or 0.76%, to 24,445.24.

Risks of an inflation flare-up remain, with oil prices near

the $100-a-barrel mark. This lifted the benchmark's energy

sector 1.2% higher.

"It's possible that we see a continuation of negative

headlines, ultimatums and deadlines for negotiations, but that

doesn't mean that stocks will react meaningfully to each one,

since markets already priced-in the worst of the conflict during

the lows made back in March," said Rick Gardner, chief

investment officer, RGA Investments.

Information technology stocks were the biggest boosts on the

Nasdaq Composite and the S&P 500, with the sector

adding 0.6%.

The Philadelphia SE Semiconductor Index hit a fresh

peak and was on track for its 16th straight day of gains -- its

longest streak ever.

Seagate ( STX ) jumped 2.2% after Barclays upgraded the data

storage firm's rating to "overweight".

EARNINGS LIFT SENTIMENT

A strong run of earnings so far has reassured Wall Street

about the health of the U.S. consumer, the growth engine of the

economy.

S&P 500 EPS estimates for 2026 and 2027 have risen by 4%

since late January, according to data from Goldman Sachs.

GE Vernova ( GEV ) advanced 13.3% after the power equipment

maker raised its annual revenue forecast. Medical device maker

Boston Scientific's ( BSX ) shares were up 8.2% after

first-quarter results.

Shares of planemaker Boeing ( BA ) rose 1.6% after a

smaller-than-expected quarterly loss, and were among the biggest

boosts on the Dow.

United Airlines, however, declined 3.7% after

forecasting second-quarter and full-year profits below Wall

Street estimates as higher jet fuel prices squeeze margins and

cloud its near-term outlook.

EV giant Tesla, chipmaker Texas Instruments ( TXN )

and Southwest Airlines ( LUV ) will report after markets close.

Adobe was 3.2% higher after it unveiled a share

repurchase program worth up to $25 billion.

Robinhood gained 2.9% after the retail trading

platform's venture fund invested $75 million in ChatGPT maker

OpenAI.

Advancing issues outnumbered decliners by a 3.06-to-1 ratio

on the NYSE and by a 2.63-to-1 ratio on the Nasdaq.

The S&P 500 posted 26 new 52-week highs and one new low

while the Nasdaq Composite recorded 79 new highs and 26 new

lows.

(Reporting by Niket Nishant and Avinash P in Bengaluru; Editing

by Devika Syamnath)