T-Mobile US said on Wednesday it officially completed the $23 billion merger with Sprint, solidifying its position as the No.3 wireless providers in the United States.

The deal comes after a long legal battle between multiple state attorneys general which argued that a merger between T-Mobile and Sprint would be anticompetitive. The combined company will now operate under the T-Mobile name and will trade on the NASDAQ as "TMUS."

The deal also enables T-Mobile and Sprint to join their high-band and low-band spectrum that could allow a faster roll-out of national 5G.

Sprint acknowledged risks in an SEC filing, saying that its internal controls over financial reporting could negatively impact the combined company.

A US federal judge approved the deal, which was originally valued at $26 billion, in February, rejecting a claim by a group of states that the proposed transaction would violate antitrust laws and raise prices.

The deal closed without a final decision from the California Public Utilities Commission. The CPUC issued a proposed decision in March to approve the merger of T-Mobile and Sprint with conditions and the final decision is slated to come on April 16.

T-Mobile and Sprint agreed to abide by any provisions set forth by the California commission.

Also, on Wednesday, a federal judge in Washington gave court approval to the Justice Department's decision to approve the merger. The department had given its approval to the deal in July on condition the combined wireless company sell off assets to Dish Network, making the latter the fourth-largest provider in the US wireless space.

The Federal Communications Commission signed off on the deal in October. FCC Chairman Ajit Pai applauded the decision and said that it would boost the US position in the race to 5G.

T-Mobile's long-time Chief Executive John Legere is stepping down from his position effective immediately as part of the deal.

Legere was originally set to leave at the end of April, with Mike Sievert, T-Mobile's president, as his successor. Legere, who helped launched the company's notable "Un-carrier" strategy, will serve on T-Mobile's board of directors.

T-Mobile shares rose 2.34 percent on the announcement.