Masayoshi Son loves a dramatic deal. His next transaction could be the most riveting yet.

The Japanese billionaire’s stake in SoftBank Group Corp. has crept up to more than a third, according to an analysis by Bloomberg News. While this has less to do with him buying additional shares and more with buybacks and cancellations reducing the total float, the effect is the same — concentrating control in the hands of SoftBank’s founder. That’s helped reignite rumors that Son is planning to take the $78 billion company private in what could be the world’s largest management buyout of all time.

It’s been clear for years that being public has lost some of the charm for Son. Every quarter he’s forced to give metrics he doesn’t believe capture the value of his firm. "We are an investment company, we’re not engaged in operations,” he said in August 2020, explaining the decision to stop reporting operating profit. "Net sales, net income, operating income don’t really make sense at all.”