US regulators have given final approval for the takeover by Japanese firm SoftBank of American mobile carrier Sprint Nextel, the Wall Street Journal said. The $21.6 billion deal gives Softbank a 78 percent stake in the US carrier and will mean a capital injection of billions of dollars into the company, the newspaper said Wednesday, quoting sources familiar with the deal. The deal had been expected early this month but required the final approval of the Federal Communications Commission (FCC), the US telecoms regulator. The commission voted unanimously in favour of the deal, the newspaper said. SoftBank\'s Tokyo-listed shares were down 0.86 percent to 5,750 yen in afternoon trading on Thursday. No other official statements have been issued and the spokesmen for Sprint, America\'s number three carrier, and the FCC have refused to comment. The report said the FCC also green-lighted Sprint\'s bid to buy out the rest of Clearwire, a heavily indebted carrier that owns valuable spectrum seen as crucial to creating a company with the clout to compete with Verizon and AT&T. Sprint was already the majority shareholder in Clearwire. Clearwire has indicated its support for the deal, but it must still be approved by its shareholders. The deal faced its biggest challenge from Dish Network, which made bids for both Sprint and Clearwire, but was forced to drop its tenders.