(Updates prices ahead of midday trading recess)

By Kevin Buckland

TOKYO, Nov 7 (Reuters) - Japan's Nikkei share average

fell on Friday, heading for its biggest weekly drop since early

April, as heavyweight tech stocks tracked an overnight decline

in U.S. peers on stretched valuation concerns.

The tech-heavy Nikkei slid as much as 2%, and was

last down 1.8% at 49,955.08, slipping below the psychologically

key 50,000 mark.

Startup investor SoftBank Group dropped 8.4% and

chip-testing equipment maker Advantest ( ADTTF ), a Nvidia ( NVDA )

supplier, slumped 7%, making them the Nikkei's top two

decliners in index-point terms.

The broader Topix lost 0.8% to 3,286.16.

Overnight, investors returned to selling the darlings of the

artificial intelligence-fuelled rally that carried Wall Street,

Tokyo and other global bourses to successive record peaks in

recent months. Nvidia ( NVDA ) slid 3.7% and AMD dropped 7.3%.

The Nikkei was headed for its worst week since the April

tariff shock as the share gauge pulled back from a record peak

touched on Tuesday. It was last down 4.7% for the

holiday-shortened week.

In October, the benchmark index rallied 16.6% to record its

best month in 35 years.

"Rather than a change in the way investors fundamentally

view AI stocks, there is this risk-off mood around how fast

these stocks have rallied," said Nomura Securities strategist

Fumika Shimizu.

Corporate results are also key for the market now, with

Japan's earnings season currently in full swing, she said.

The three biggest percentage decliners on the Nikkei on

Friday all posted disappointing financial results. Environmental

equipment supplier Kanadevia ( HIZOF ) tumbled 20% and

confectionary maker Ajinomoto ( AJINF ) and electronic component

manufacturer Taiyo Yuden ( TYOYF ) each shed more than 16%.

The biggest percentage gainer was also driven by corporate

results, with HR technology firm Recruit Holdings ( RCRRF )

jumping 15%.

Embattled automaker Nissan Motor ( NSANF ) got some respite

after reporting a return to operating profit. Its shares climbed

5.3%.