SoftBank Group has halted talks about an acquisition of U.S. data center operator Switch, a setback to founder Masayoshi Son¡¯s ambition to roll out Stargate artificial intelligence infrastructure, according to people familiar with the matter.

For months, Son pursued a deal of around $50 billion for Switch, convinced that direct control of the latter¡¯s network of energy-efficient data centers would help the $500 billion Stargate push to generate computing power for partner OpenAI.

But earlier this month, Son conceded that a full acquisition was off the table and scrapped a planned January announcement, the people said, asking not to be named because the matter is private. The two sides remain in active discussions about a partial investment or a partnership, they said.