TOKYO -- Concerns over SoftBank Group CEO Masayoshi Son's ambitious bets on technology companies are deepening after he led nearly $30 billion worth of investments in startups in the past year alone. 

SoftBank has scaled back its planned investment in co-working space startup WeWork to $2 billion after holding talks to inject as much as $16 billion, the Financial Times reported on Tuesday, citing the recent tech stock rout and concerns among investors in its $100 billion Vision Fund. It marked the first clear sign of pushback against Son's dealmaking since the fund was launched two years ago. 

Analysts say the group is unlikely to slow down its investments, given Son's strong belief in the information revolution over the long term. He has said the "synergy group strategy" of investing in the world's leading companies in artificial intelligence and other key areas will enable SoftBank to grow for 300 years. 

But some say questions over the hefty premiums, given for private tech companies like U.S. ride-hailing giant Uber Technologies and Chinese video-sharing app operator Bytedance, will multiply if tech stocks continue to face turbulence.

The recent turmoil in stock markets has already hit SoftBank's own stock price, which is closely tied to the performance of its investments. Shares have declined more than 30% from last year's peak in September, giving the company a market capitalization of around 8.4 trillion yen ($77 billion). 

"Son has a track record of reading trends in technology," said one person familiar with Son's strategy. "But does he understand the management and underlying technology of every company that he is investing in now? I am skeptical." 

SoftBank and the Vision Fund led a $30.9 billion fund-raising in tech companies in 2018, according to data compiled by the Nikkei Asian Review. This figure, which only includes deals worth $100 million or more, is slightly more than the $29.7 billion in proceeds raised by companies that were listed on the New York Stock Exchange last year. The NYSE was the second-largest exchange by IPO proceeds last year, trailing Hong Kong's $35.4 billion, according to Ernst & Young. 

SoftBank Group CEO Masayoshi Son stands in front of a panel showing the companies he has invested in, during a news conference in Tokyo on Nov. 5.   © Reuters

The flurry of deals cemented SoftBank's position as the world's largest tech investor, despite setting up the Vision Fund only two years ago. More than 40% of SoftBank's investments came during the last three months of 2018, despite questions surrounding its ties to Saudi Arabia after a journalist was murdered at the Saudi consulate in Istanbul in early October. 

Throughout the year, SoftBank was most active in the transportation sector, investing in companies like Uber, General Motors' self-driving car unit GM Cruise Holdings, and car sharing startup Getaround. But the group also made big bets in fields such as real estate and expanded geographically. Among the biggest deals in recent months were a $1.1 billion funding round for View, a U.S. window glass maker, and another $1.1 billion for Indonesian e-commerce company Tokopedia. 

But the scaled-down investment in WeWork is a sign that potential conflicts of interest between government-backed funds in Saudi Arabia and Abu Dhabi, the largest investors in the Vision Fund, may limit the scope of Son's investments. SoftBank itself, not the Vision Fund, is participating in the latest WeWork deal, according to reports. SoftBank and WeWork both declined to comment. 

On the positive side, SoftBank raised some $23 billion from the initial public offering of its mobile unit, SoftBank Corp., in December. While the subsequent fall of the stock has dented the group's reputation, it gave SoftBank financial flexibility to continue making investments even if outside investors decide not to participate. 

Some analysts also expect 2019 to be the first year when key companies under its portfolio will go public and generate major returns for the group and its investors. 

Uber and Didi Chuxing, two high-profile investments, "are likely to IPO and generate significant value for the fund," said Sanford C. Bernstein analyst Chris Lane. "We also expect the Vision Fund to close and deploy nearly 75% of its capital by the end of the year." 

The performance of the fund is crucial for SoftBank's future. Son has been steering the group away from the traditional telecoms business, listing its domestic mobile arm and pursuing a merger between majority-owned U.S. mobile carrier Sprint and its rival T-Mobile. The latter deal, if approved by regulators, is expected to lower SoftBank's stake in the combined entity to about 27%. 

SoftBank itself accounts for roughly a third of the total investment in the Vision Fund, an unusual scheme for a venture capital fund that ties the group's earnings closely with the value of its portfolio companies. Thanks to a largely strong performance in tech stocks for the first nine months of the year, the Vision Fund accounted for more than 40% of the group's operating profit for the March-September period. 

Son, who started SoftBank as a personal computer software distributor, is known for making a handful of wildly successful investments that have outshone his failures. The most prominent is a $20 million investment in Alibaba in 2000, a stake that ballooned to roughly $60 billion in value when the Chinese e-commerce company went public in 2014.