This would be Son’s second venture into robotics. In 2012, SoftBank acquired French company Aldebaran Robotics SA and two years later unveiled Pepper, a $1,600 humanoid promoted as the world’s first robot endowed with emotions. Son envisioned building an ecosystem of apps that would let Pepper man storefronts as well as entertain people at home. But culture clashes between the Japan parent and French engineers as well as challenges of creating artificial intelligence capable of understanding natural language has left Pepper underwhelming and with lackluster adoption limited to Japan.

“SoftBank may not have struggled as much if they bought a better robotics company” instead of Aldebaran, Takahashi said.

The shares of SoftBank rose 7.4 percent in Tokyo, buoyed by Alibaba Group Holding Ltd.’s 13 percent jump in the U.S. that boosted the value of SoftBank’s stake in the Chinese e-commerce giant to $105.6 billion.

“Typically, when Son makes a big acquisition, the markets are worried,” said Tomoaki Kawasaki, an analyst at Iwai Cosmo Securities Co. “If this deal goes through the Vision Fund, no one will fret about the impact on SoftBank’s balance sheet.”

Eoin Treacy's view

There are two reasons Google decided to sell Boston Dynamics as far as I can see. The first is that the agile robots the company produces are the equivalent of scaled up versions of remote control cars, lacking any artificial intelligence to speak of. The second is that the most obvious route to commerciality is through the military and that runs counter to Google’s culture.

By acquiring Boston Dynamics, Softbank, or the Vision Fund, will gain access to leading optics, motor, power management and engineering knowhow. The big question is where the artificial intelligence will come from to make these machines truly useful. I encountered the Pepper robot while in Japan in April and have to say it was rather disappointing that it was limited to Japanese language inputs but perhaps more interesting was that its role in the store I visited was as little more than a novelty information board.  That highlights just how much of a challenge developing artificial intelligence for practical real world applications is.

Softbank moved to a new recovery high on Friday and pulled back with much of the rest of the technology sector today. However a sustained move below the trend mean, currently near ¥8000, would be required to question medium-term scope for additional upside.  

Softbank has acquired mobile chips through ARM Holdings, robots through Boston Dynamics, bitcoin infrastructure, fitness trackers, ride sharing and machine learning through its acquisition of Fortress Investment Group. That represents a trend of concentration in the major tech themes of today with reasonable potential for commercialisation but it is also a bet that nothing else will come along in the meantime to displace them.