Japan's Nikkei falls as tech shares drag; Astellas surges

By Satoshi Sugiyama

TOKYO, Feb 5 (Reuters) - Japan's Nikkei share average fell on Thursday, dragged lower by technology stocks on lingering valuation concerns, joining a wider Asian markets slump on concerns about the exploding costs of AI investment.

The benchmark Nikkei 225 Index .N225 slid 0.9% to close at 53,818.04. The broader, less tech-heavy Topix .TOPX declined a more muted 0.1% to 3,652.41.

SoftBank Group 9984.T tumbled 7% after its affiliated chip design firm Arm Holdings O9Ty.F missed analysts' expectations on licensing revenues.

"Chip-related stocks are expected to be soft as concerns mount in the U.S. over rich valuations and AI investment," said Takayuki Miyajima, senior economist at Sony Financial Group.

"But in Japan, selective buying tied to earnings is likely to continue."

Semiconductor-related stocks fell in early Tokyo trading, with chip-maker Rohm 6963.T down 9.1% to become the worst percentage loser on the Nikkei, while sector supplier Advantest 6857.T dropped 4.8% and chipmaking device company Disco 6146.T sank 4.4%.

There were 137 advancers on the Nikkei index against 88 decliners - evidence of the outsized influence of a handful of heavyweight tech names.

The pharmaceuticals sector IPHAM.T was the top performer among the Tokyo Stock Exchange's 33 industry groups, led by Astellas Pharma's 4503.T 10% surge after the company lifted its net profit forecast for this fiscal year by nearly five times.