Comcast will announce a deal to acquire Time Warner Cable in an all-stock deal worth more than $44 billion that will unite the biggest and second largest cable television operators in the country, according to people briefed on the matter.

The surprise merger - expected to be announced Thursday - is likely to bring to an end a protracted takeover battle that a smaller cable rival, Charter Communications, has been waging for Time Warner Cable, and will be the second major deal for Comcast in recent years to radically reshape the U.S. media landscape.

Time Warner Cable shareholders will receive 2.875 shares of newly issued Comcast common stock for each of their shares. Based on Comcast's closing price of $55.24 Wednesday, that values each Time Warner Cable share at about $158.82 each.

The combination of the two is certain to attract antitrust scrutiny by regulators.

David Faber of CNBC earlier reported the deal.

Charter had been courting Time Warner Cable for months. Last month, Charter had offered to acquire the company for $132.50 a share - roughly around the market price of Time Warner Cable at the time.

The board of Time Warner Cable unanimously rejected that proposal, calling it "grossly inadequate."

A deal by Comcast would come four years after the cable giant agreed to acquire NBC Universal from General Electric in a transaction that valued NBC Universal at $30 billion.

Morgan Stanley, Allen & Co. and Citigroup had been advising Time Warner Cable on its defense from Charter, with Paul, Weiss, Rifkind, Wharton & Garrison providing legal advice. Comcast is being advised by JPMorgan Chase, among others.