Jeffrey L. Bewkes, the chief executive of Time Warner, continued to trim what has for years been the world’s largest media company by announcing Wednesday that it would completely spin off its cable company.

The news  which was not unexpected and follows an earlier transaction in which a portion of the cable unit was spun off into a separate public company  came as Time Warner reported quarterly earnings that were largely in line with Wall Street’s expectations.

“We’ve decided that a complete structural separation of Time Warner Cable, under the right circumstances, is in the best interests of both companies’ shareholders,” Mr. Bewkes said Wednesday in a statement. “We’re working hard on an agreement with Time Warner Cable, which we expect to finalize soon.”

The company’s shares rose as high as $15.35 in premarket trading, after closing at $15.27 on Tuesday. In regular trading Wednesday, shares were down about 2 percent.