AMSTERDAM (Reuters) - Investors and analysts are reviewing their assessments of computer chip equipment maker ASML, they said on Wednesday, after the company cut 2025 financial guidance, citing weakness in markets other than AI and delayed orders.

The position of ASML, Europe's most valuable technology company, as an essential supplier to chipmakers is not in question. But doubts have emerged over its short term sales, and, for the longer term, whether it can continue to outgrow the overall market.

Tuesday's change to guidance triggered the biggest selloff in ASML's shares in two decades.

Shares fell another 4.9% to 635.60 euros at 0840 GMT on Wednesday, down from an all-time high above 1,000 euros ($1,088) a share in July that followed a decade-long surge based on ASML's dominance of the market for lithography tools, needed to create circuitry.

After the pandemic leap in demand, ASML said some customers have delayed new plants and upgrades, including makers of the logic chips used in smartphones, PCs and other devices.

Manufacturers that make the memory chips that go into them also plan fewer expansions and are relying on existing technology for longer.

"There need to be limits to the expectations we investors put in any single company," said Nick Rossolillo of Concinnus Financial, who has owned ASML stock since 2022.

"That's especially the case for an upstream equipment supplier highly reliant on the spending plans of its manufacturing customers."

Though the company did not identify which customers were behind the guidance cut, analysts looked first at TSMC, which makes AI chips for Nvidia and smartphone chips for Apple, and is ASML's biggest customer.

"The strong sales trends at TSMC are a misleading indicator for the overall health of the semiconductor industry," said analyst Michael Roeg of Belgian investment bank Petercam Degroof.

"TSMC has been spending rather low capex numbers so far this year, and they may do so again next year because their overall (plant) utilisation is not as good as their sales numbers suggest."

Among ASML customers that make logic chips, Intel said in August it would cut capital spending by $10 billion in 2025, while Samsung has said it faces challenges at the factory it is building in Texas.

Roughly a quarter of chipmakers' spending on chipmaking tools goes to ASML, though some analysts believe that may decline in the future.

ASML's executives are expected to address analysts on a call later on Wednesday.

($1 = 0.9190 euros)