The combined entity would have “tremendous” power, Hesse said in an interview at a wireless industry conference in Orlando, Florida. He said AT&T and Verizon Wireless would hold 79 percent of the U.S. market if regulators approve the deal.

Sprint shares fell 14 percent yesterday on concern AT&T’s $39 billion takeover of T-Mobile, announced March 20, will leave the Overland Park, Kansas-based carrier a weaker No. 3 player in the U.S. The deal still needs regulatory approval. Sprint also held talks about buying T-Mobile, people with knowledge of the matter said this month.

Hesse, 57, said Sprint will file its concerns to Congress during the review. The U.S. House Judiciary Committee said yesterday it will hold a hearing on the takeover. The committee will look into possible anticompetitive impacts, said Representative Lamar Smith, a Texas Republican who heads the panel.

Hesse declined to say whether Sprint had held talks with T- Mobile. He told an audience at the wireless event that the acquisition by AT&T would consolidate too much power in the mobile-phone market.

“I have concerns it would stifle innovation,” Hesse said.

Sprint rose 11 cents to $4.47 at 4 p.m. in New York Stock Exchange composite trading.