Masayoshi Son, celebrated Japanese deal-maker, just negotiated himself into a corner.
Son's SoftBank Group Corp. ended talks Saturday to combine its Sprint Corp. with T-Mobile US Inc., a merger that would have united the third and fourth-largest wireless operators in the U.S.
In the end, the 60-year-old billionaire balked at the idea of giving up control over the company he sees as central to his vision of the future.