(Sharecast News) - Asian stock markets were mixed on Monday, with small gains in Hong Kong, Sydney and Singapore met with losses in Shanghai and Mumbai and big sell-off in Seoul.

Renewed fears about lofty valuations in the tech sector and overspending on AI infrastructure hammered sentiment surrounding semiconductor stocks, with South Korean heavyweights Samsung Electronics and SK Hynix helping to drag the benchmark KOSPI index down 3.7% to its lowest since 11 August. Traders in Seoul were returning to their desks after a public holiday on Friday.

"The move highlights the uneven global risk backdrop: US assets remain supported by AI-linked earnings optimism, while Asia is more exposed to energy-import costs, FX sensitivity and semiconductor volatility," said Patrick Munnelly, partner of market strategy at Tickmill Group.

Elsewhere, the Shanghai Composite fell 0.4% and the Sensex dropped 0.8%, while the Hang Seng rose 0.3%, the S&P/ASX 200 gained 0.8% and the Strait Times Index rose 0.3%. Japan's Nikkei 225, meanwhile, was closed for a public holiday.

Markets in Sydney in particular were given a boost by the blue chip mining sector, with BHP, Fortescue and South32 tracking commodity prices higher.

Meanwhile, Taiwan's TAIEX benchmark finished flat, cutting earlier losses, as investors looked ahead to the latest quarterly earnings from chipmaking giant TSMC, which is tipped to report its sixth consecutive quarter of record profits on Thursday. The consensus forecast is for a third-quarter net profit of T$746bn, up 65% on last year.

In other news, the inflation rate in India jumped to a two-year high of 5.5% in September, according to official data, up from 4.8% in August. This was the highest since October 2024 and above the 5.4% expected by economists.

Oil prices hit a two-week high, with Brent crude and West Texas Intermediate both up 0.9% at $105.64 and $92.67 a barrel, respectively, as investors weighed up Donald Trump's declaration of an "energy ceasefire" between Russia and Ukraine against another Houthi attack on a Saudi airport over the weekend.