TOKYO — A former Google executive and Silicon Valley star was on course to be the next chief executive of SoftBank of Japan, one of the world’s most prominent technology conglomerates. Now he is leaving, in an abrupt shakeout that shows cracks in SoftBank’s global ambitions.
When the executive, Nikesh Arora, was poached two years ago from a coveted role as Google’s head of business operations, the hire was widely considered a coup for SoftBank. Its billionaire founder and chief executive, Masayoshi Son, crowned Mr. Arora heir apparent.
Mr. Arora was vaunted for his deal-making prowess and seen as an international executive who would help transform SoftBank with a flurry of investments. One of Mr. Son’s most cherished ambitions was to turn SoftBank, a Japanese business with some notable overseas names like the American carrier Sprint, into a truly global enterprise.
The honeymoon did not last.
Investors have criticized Mr. Arora recently for his record of managing SoftBank’s overseas deals. Investments in start-ups like DramaFever and Housing.com, these shareholders have said, appear to have soured as the companies have faltered.
And the carefully orchestrated succession plan — or what appeared to be — has collapsed. Mr. Son decided he was not ready to give up the reins soon.
Mr. Son, 58, said in a statement that he still wanted to “work on a few more crazy ideas” at SoftBank. Mr. Son cited differences over when Mr. Arora would take over as chief executive as the reason he had agreed to step down. Mr. Arora, who was born in India, holds the titles of president and chief operating officer.
“This will require me to be C.E.O. for at least another five to 10 years — this is not a time frame for me to keep Nikesh waiting for the top job,” Mr. Son said.
Mr. Arora, 48, also presented the parting as amicable. “Masa and I are still in love with each other,” he posted on Twitter. “I will support everyone I invested in, and they know that.”
Mr. Arora’s legacy — good or bad — will ultimately be determined by his investment record.
SoftBank’s strategy is centered on acquiring other companies, from established businesses to tiny start-ups. Shortly before Mr. Arora arrived, SoftBank bought Sprint for $21.6 billion, a major expansion of Mr. Son’s empire overseas. The Japanese conglomerate also made a fortune when its early investment in the Chinese e-commerce company Alibaba slowly swelled to billions of dollars in value.
After joining SoftBank, Mr. Arora was put in charge of picking takeover targets around the world. His mandate was to diversify a company that, despite the Sprint acquisition and others, still makes about 70 percent of its operating profits in its home market. It owns a major mobile phone network and a controlling interest in Yahoo Japan, among other domestic assets.
Mr. Arora struck more than a dozen deals, placing bets on technology, telecommunications and media companies in India, Indonesia and Singapore, among other countries. SoftBank paid $1 billion for a stake in the Korean e-commerce company Coupang. It plowed $250 million into WME-IMG, the giant American media and sports agency. India has been a particular focus, and Mr. Arora led investments into businesses like Snapdeal and OYO Rooms, which aspire to be its Amazon and Airbnb.
Recently, SoftBank has been selling assets and raising cash, a pattern that has been a prelude to big, strategic deals. On Tuesday it sealed an agreement to sell its majority stake in Supercell, the developer of “Clash of Clans” and other mobile games, to China’s Tencent Holdings for about $8.6 billion. It also recently sold about $10 billion of shares in Alibaba.
Expectations for Mr. Arora had been high. Besides his Google pedigree, he had been unusually well paid.
In his first six months at SoftBank, Mr. Arora earned 16.6 billion yen, or $159 million at current exchange rates, including a signing bonus, according to company disclosures. That made him one of the best compensated executives in the world during that period, and one of the highest paid executives in Japan, a country known for relatively low pay at the upper echelon.
He earned about 8 billion yen last year. Mr. Arora made a huge personal financial commitment to SoftBank in 2015, buying 60 billion yen of the company’s shares.
But some of his bets haven’t panned out. DramaFever, a Korean video site, shed traffic months after SoftBank invested in the business, prompting the Japanese company to find buyers for some of its stake.
This year, SoftBank has defended Mr. Arora against criticism from a group of mostly anonymous international shareholders, who laid out their case against Mr. Arora in a letter to the company’s board in April. They said a number of start-ups he backed have fizzled. They also questioned his decision to remain an adviser to an American investment firm, Silver Lake, that could potentially compete with SoftBank for deals.
“Mr. Arora’s investment strategy as the C.E.O. of SIMI appears to be nothing more than throwing a dart at a dart board,” a lawyer representing the investors wrote in the letter, referring to SoftBank’s internet and media operations as SIMI. “How many more millions of dollars of shareholder value must be wasted before the board realizes something must be done?”
A representative for Silver Lake declined to comment. Advisers like Mr. Arora generally receive limited insight into the private equity firm’s deliberations and spend only a few hours a month with Silver Lake.
SoftBank said on Monday that an internal panel set up to investigate the investors’ claims had found no evidence of conflict of interest or other misconduct. Still, the episode may have shaken Mr. Son’s trust in Mr. Arora, soured Mr. Arora on SoftBank, or both.
“Clean chit from board after through review. Time for me to move on,” Mr. Arora said in another tweet on Tuesday.
And it was always an open question whether Mr. Son would readily give up control.
Mr. Arora was one of only a small number of non-Japanese to have attained a top management position at a major Japanese company. He faced fewer bureaucratic and cultural obstacles than most, in part because SoftBank’s power structure is simple. SoftBanks starts and ends with Mr. Son, who founded the company in the 1980s and runs it with unquestioned authority.
“I feel my work is not done,” Mr. Son said in a statement on Tuesday.
An earlier version of this article referred incorrectly to the Chinese company Alibaba’s main line of business. It is e-commerce, not search.