Softbank Corp.'s Masayoshi Son has a history of picking winners. Investors say his latest choice may not be a repeat performance.
Son's $20 million investment in Alibaba Group Holding Ltd. may now be worth as much as $10 billion, and his $1.2 million purchase of a stake in Yahoo Japan Corp. is worth $7 billion.
Those past successes hasn't convinced investors that Son's strategy of entering the U.S. mobile phone market by buying Sprint Nextel Corp. makes sense. Softbank shares plunged the most on record, wiping $1.3 billion from Son's net worth, after it was first reported to be in acquisition talks last Thursday. Shareholders are concerned the $34 billion company may be saddled with debt or dilute earnings by issuing new shares to fund multiple acquisitions announced in the past month.