By Sherry Qin

Asian stocks ended mostly lower, with South Korea, one of the region's biggest beneficiaries of the global artificial-intelligence boom, leading losses on concerns over the sustainability of spending in AI infrastructure.

After triggering two circuit breakers last week, South Korea's Kospi suffered another heavy selloff on Thursday, ending 7.9% lower as chip giants Samsung Electronics and SK Hynix tumbled 9.1% and 15%, respectively.

The losses followed weakness overnight on Wall Street, where most AI infrastructure stocks lost ground after a report said that Meta plans to build a cloud business to sell excess computing power.

Meta's reported move posed a question for Asia's AI infrastructure builders: "What if hyperscalers are building more compute than they can use profitably?" said Charu Chanana, chief investment strategist at Saxo Markets.

The fortunes of Asia's semiconductor companies are closely tied to Big Tech's AI spending, and any sign of slowing investment could hurt investor sentiment.

"Hyperscalers may now be preparing for a world where they have to monetize excess capacity rather than just keep building at any price," Chanana added.

As the AI trade gets more crowded, with numerous investors and hedge funds pouring money into the same hyperscaler and infrastructure builders stocks, the positioning becomes increasingly fragile.

The latest selloff raises the question "whether this year's AI-driven equity surge has run too far, too fast," Tickmill Group analyst Patrick Munnelly said in a note.

Japan's Nikkei Stock Average closed 2.5% lower as Kioxia tumbled 13.5% and Tokyo Electron dropped 7.4%. China's Shanghai Composite Index lost 2.0%, while the tech-heavy Chinext Index gave up 5.7%.

Hong Kong's Hang Seng Index bucked the trend, ending 0.8% higher as investors returned from a holiday. Heavyweight Chinese internet stocks, including Alibaba and JD.com, reversed some of their recent weakness to lead gains.

While equity markets were weighed by renewed AI jitters, oil prices continued to fall as traffic through the Strait of Hormuz recovered, prompting several banks to cut their oil-price forecasts.

"Expectations of normalized flows quickly pushed crude prices back to pre-conflict levels, reviving the oversupply narrative," OCBC strategists said.

OCBC lowered its third-quarter forecast for Brent crude oil to $75 a barrel from $85 a barrel, while UBS said it expects Brent crude to average $84 a barrel this year, down $9 from its earlier forecast.

Front-month WTI crude oil futures were 0.55% lower at $68.20 a barrel, while Brent crude oil futures were down 0.6% at $71.12 a barrel.

Write to Sherry Qin at sherry.qin@wsj.com