Sprint and T-Mobile said on Saturday they had called off merger talks, denting the dealmaking credentials of SoftBank CEO Masayoshi Son, who has raised close to $100 billion for his Vision Fund to invest in technology companies.

It also puts Son under pressure to find another way to turn around the carrier, the No. 4 U.S. provider which is weighed down with $38 billion in debt and is struggling to compete with Verizon Communications and AT&T.

“I feel good about this decision,” Son said of the move to call off merger talks.

“Even if it is tough for the next three or four years, on a five or ten year timescale scale it is a strategically indispensable company,” he told reporters at SoftBank’s earnings briefing on Monday.

However, when asked about the failed T-Mobile merger, Son added “the door is open” if its management rights are preserved.

SoftBank said on Sunday it would raise its stake in Sprint to under 85% from 83%, the most it can hold without triggering a tender offer for the remaining shares.

“U.S. telecoms is indispensable infrastructure and as an investing company SoftBank should have the ability to control such infrastructure,” Son said.

The Japanese tech and telecoms firm is funneling money to U.S. firms as it invests in technology companies around the world, including through its Vision Fund, as founder Son pursues his vision of a future driven by artificial intelligence, interconnected devices, and robotics.

Among the dozens of technology firms to receive investments are chipmaker Nvidia, shared-office space company WeWork and Chinese ride hailing firm Didi Chuxing.

In May, SoftBank announced it had raised over $93 billion for the Vision Fund, the world’s largest private equity fund with backers including Saudi Arabia’s sovereign wealth fund, Apple and Foxconn.

The company is finalizing conditions for investment in Uber Technologies that must be met, Son said, including pricing and negotiations with existing investors.

“I believe that Uber is a good company,” Son said, adding “whether we make an investment in Uber or not is not decided.”

SoftBank, along with other investors, is expected to purchase as much as $10 billion in Uber shares, most of them from employees and existing investors in a so-called secondary offering.

SoftBank reported on Monday a 21% rise in second-quarter operating profit as the value of its technology investments grew.

Profit for the July-September quarter rose to 395.6 billion yen ($3.5 billion) from 328.1 billion yen a year earlier. Excluding profit from the Vision Fund segment, income would have fallen 4%.

In the six months through September the Vision Fund segment posted operating income of 186.2 billion yen.

SoftBank shares closed down 2.6% in Tokyo on Monday. The benchmark Nikkei 225 index closed flat.