NEW YORK ( TheStreet) -- Sprint ( S - Get Report) confirmed Thursday its' in discussions with Japanese firm Softbank about a possible "substantial" investment in the No. 3 U.S. telecom provider.

"Although there can be no assurances that these discussions will result in any transaction or on what terms any transaction may occur, such a transaction could involve a change of control of Sprint," explained the Overland Park, Kansas-based company in a statement.

Sprint added that it does not intend to comment further "unless and until an agreement is reached."

Investors responded positively to the announcement, pushing Sprint's shares up 18.06% to $5.95.

Early on Thursday, Reuters reported that the Japanese carrier is in talks to buy a majority stake in Sprint for more than 1 trillion yen ($12.8 billion).

Sprint, which is keen to participate in industry consolidation, was recently rumored to be considering a counter-bid for MetroPCS ( PCS), which is merging with T-Mobile USA.

MetroPCS and T-Mobile USA disclosed earlier this month details of their planned merger. The combined company will use T-Mobile's branding and have 42.5 million subscribers.

MetroPCS shares tumbled 4.65% to $11.48 on Thursday.

--Written by James Rogers in New York.

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