US regulators on Friday approved the $21.6 billion takeover of mobile carrier Sprint by Japan\'s SoftBank, a deal with the potential to shake up the American wireless market. Approval by the Federal Communications Commission was the last major hurdle following a hard-fought acquisition battle, and allows SoftBank to take a 78 percent stake in Sprint. SoftBank had targeted Sprint as a way to gain entry into the hot US telecom market. But the Japanese company\'s efforts ran into competition from Dish Network, which forced SoftBank to increase its offer by $1.6 billion from the original $20 billion proposal.  The deal is the largest overseas acquisition ever by a Japanese firm. Sprint stockholders will retain a 22 percent stake in the new firm. \"Today is a good day for all Americans who use mobile broadband services,\" said acting FCC chair Mignon Clyburn, who added that the deal \"would serve the public interest.\" The US regulator also approved a separate deal that allows Sprint to take full control of the wireless broadband provider Clearwire, giving it more spectrum to compete against bigger carriers such as AT&T and Verizon. Clearwire shareholders are set to vote Monday on that deal.  Clyburn said the deals would lead to increased investment in Sprint\'s and Clearwire\'s networks and would likely \"accelerate deployment of mobile broadband services and enhance competition in the mobile marketplace, promoting customer choice, innovation and lower prices.\" The SoftBank deal received clearance from US national security officials in May under the condition of appointing an independent member to the Sprint board of directors to serve as security director.The director, who must be approved by US authorities, would oversee national security matters and serve as a point of contact for US agencies.  The FCC order approving the transaction said that, \"based on the record in the proceeding, we find that any national security, law enforcement and other related concerns have been adequately addressed.\" A statement issued by Sprint and SoftBank said the deal would close \"in early July\" and the company would soon begin deploying more fourth-generation (4G) wireless networks and services. Sprint chief executive Dan Hesse welcomed the FCC approval. \"Just two years ago, the wireless industry was at the doorstep of duopoly, but with these transformative transactions, we are one step closer to a stronger Sprint, which will better serve consumers, challenge the market share leaders and drive innovation in the American economy,\" Hesse said. In the statement, SoftBank chairman and CEO Masayoshi Son said, \"The FCC\'s thoughtful review and approval of these transactions represents an important step toward creating a more competitive US wireless marketplace.\" He added that \"SoftBank\'s investment in Sprint will bring innovation and increased customer focus, which will enable us to begin creating a true competitor in a market dominated by two companies.\"