Charter Communications Inc said it would buy Time Warner Cable Inc in a deal valued at $78.7 billion, as the second and third largest U.S. cable operators look to better compete with market leader Comcast Corp.

The equity portion of the deal is $55.76 billion based on Time Warner Cable's diluted shares outstanding as of March 31. The company had long-term debt of $22.64 billion, according to its latest quarterly report.

The offer values each Time Warner Cable share at about $195.71 based on Charter's closing price on May 20, the companies said in a statement on Tuesday.

The deal comes at a time when the U.S. cable-and-internet companies are looking to cut costs and gain pricing advantages through a flurry of consolidation.

Time Warner Cable's shares rose 11.6 percent to $190.50 in premarket trading, while Charter's stock was up 3.2 percent at $181.