Japan's Nikkei falls a second day as AI, chemical shares give up gains

By Rocky Swift

TOKYO, Jan 8 (Reuters) - Japan's Nikkei share average slid for a second straight day on Thursday, dragged lower by profit-taking in the artificial intelligence (AI) sector and as trade tensions heat up with China.

The Nikkei 225 Index .N225 fell 0.6% to 51,660.50 as of the midday break. The broader Topix .TOPX edged down 0.1%.

The Nikkei gauge marked a record closing high on Tuesday, with gains over recent months driven largely by optimism over AI. SoftBank Group 9984.T, a major domestic investor in AI, and chip sector heavyweights like Advantest Corp 6857.T and Tokyo Electron 8035.T have been major beneficiaries of the trend.

"The decline in certain high-priced stocks, particularly AI and semiconductor-related stocks, is weighing heavily on the index today," said Nomura Securities strategist Wataru Akiyama.

Shares in Japanese chemical manufacturers slid after China's commerce ministry said it is launching an anti-dumping probe into imports of chemicals used in chipmaking.

The probe into imports from Japan of dichlorosilane comes amid strained ties between the two countries with China also this week announcing a ban on exports of dual-use items to Japan.

Shin-Etsu Chemical 4063.T sank 3.4% while Mitsubishi Chemical 4188.T lost 0.4%.

There were 105 advancers on the Nikkei index against 118 decliners. SoftBank Group was the biggest loser, falling 4.6%, while Sumitomo Pharma 4506.T was the sharpest gainer, up 10.7%.