SoftBank Group Corp reported a quarterly loss on Monday, as its Vision Fund unit took a US$10 billion hit from a decline in the value of its portfolio companies and as China's regulatory crackdown on tech firms weighed.

The Japanese tech conglomerate will buy back up to nearly 15 per cent of its shares, it said, spending a trillion yen (S$12.14 billion) in the process, and adding to the 2.5 trillion yen record buyback it completed in May.

While chief executive Masayoshi Son has likened SoftBank to a goose laying "golden eggs", Monday's results underscore the extent its investment business is reliant on the initial public offering market, which has slowed, and China, where valuations continued to drag on its portfolio.

"We are in the middle of a blizzard," he told a presentation, adding he was "not proud" of the Vision Fund's performance in the quarter. Yet he said the company was making steady steps to double the numbers of "golden eggs" compared to last years.

The SoftBank Vision Fund is a venture capital fund founded in 2017 that is part of the SoftBank Group. With over US$100 billion in capital, it is the world's largest technology-focused investment fund. In 2019, SoftBank Vision Fund 2 was founded. The total fair value of both funds as Mar 31, 2021 was US$154 billion.

The group's largest asset, Chinese e-commerce firm Alibaba , saw its valuation fall by around a third in the second quarter. Its stake in Chinese ride-hailer Didi, acquired for US$12 billion, was valued at US$7.5 billion.

Another notable hit was online retailer Coupang, which gave up a third of its value.

Redex Research analyst Kirk Boodry said: "The strategy of let's create the perception of enhanced value by taking things public hasn't really worked this year."

Bright spots for the Vision Fund include its India portfolio with ride-hailer Ola and logistics firm Delhivery targeting listings.

"The pipeline is very robust," Navneet Govil, Vision Fund's chief financial officer, told Reuters in an interview.

The planned listing of South-east Asian ride-hailer Grab via a merger with a special-purpose acquisition company (SPAC) will provide further valuation upside, he said.

The group's net loss is 397 billion yen, compared to a profit of 628 billion yen a year earlier. Vision Fund's investment loss totalled 1.167 trillion yen.

SoftBank has been trimming stakes in companies like ride-hailer Uber Technologies and food delivery firm DoorDash following the expiry of lock-up periods. The group has returned US$9.8 billion to investors and is currently focusing on investing through its second Vision Fund that has US$40 billion in committed capital.

The second fund had invested US$33.5 billion in 157 startups at the end of the quarter. Eight of those firms have already listed.

SoftBank shares, which have lost around a quarter this year, closed down 0.77 per cent at 6,161 yen ahead of earnings on Monday.

Son says change in the net asset value (NAV) of SoftBank's holdings is a better judge of performance than profit. Its NAV was 15,450 yen per share on July 1, according to the conglomerate's calculations, when its share price was 7,775 yen. -Reuters