Japanese mobile carrier Softbank shares soared 10 percent in Tokyo trade on Tuesday as investors piled back into a stock that has been pounded since news of its $20 billion takeover of Sprint Nextel emerged. Just before 10:00 am (0100 GMT) the shares were 10.05 percent higher at 2,496 yen ($31.69). The ambitious cross-ocean marriage would see Softbank acquire 70 percent of Sprint Nextel, the third-biggest US mobile firm behind AT&T and Verizon Wireless, by the middle of next year. Investors dumped the shares on Friday as Softbank confirmed it was in talks with Sprint, Concerns about how it would finance the purchase and the strategy behind the monster deal pushed Softbank stock down 17 percent and then another 5.3 percent on Monday before the deal was confirmed. Tuesday\'s spike may be largely driven by bargain hunters looking to pick up the embattled stock on the cheap. \"Now that the deal is official, some share buyback momentum is likely,\" said a senior strategist at a Japanese brokerage. Chief executive Masayoshi Son, a well-known tech entrepreneur and Japan\'s second-richest man, acknowledged on Monday that his firm was jumping into the US mobile market where it has no foothold or experience, and taking over a heavily indebted firm that lost $2.89 billion last year. Moody\'s and Standard & Poor\'s both put Softbank\'s credit rating under review for a possible downgrade, saying it would heap pressure on an already debt-heavy balance sheet. The agreement catapults Softbank, little known outside Japan, to third spot globally among cellular firms after China Mobile and Verizon. While the deal has raised eyebrows among some analysts and investors, Credit Suisse analyst Hitoshi Hayakawa said it may prove to be an astute move. \"This has the potential to transform the Softbank Group into a behemoth straddling Japan, the US, and Asia,\" he told Dow Jones Newswires. \"This opening for industry realignment on a historic scale presents a excellent opportunity to invest.\"