• by Fern Siegel , July 1, 2011

Expected since spring, AMC Networks has officially spun off from Cablevision, now a separate public company trading on Nasdaq. Formerly Rainbow Media Holdings, AMC Networks changed its name as part of its corporate restructuring.

The renamed AMC Networks took its name from the division that houses the Emmy-winning dramas "Mad Men" and "Breaking Bad"; it picked up 15% in ad revenue gains in the first quarter of 2011.

Overall AMC Networks revenue -- including subscriber fees -- rose 10% to $272.9 million in Q1.

As part of the spinoff, Cablevision Class A and B stockholders will receive one share of AMC Networks common stock for every four shares of Cablevision they hold. Cablevision is expected to focus on its cable-systems business; last year it spun off Madison Square Garden Co., owner of the New York arena and the New York Knicks.

Josh Sapan will serve as president, CEO of AMC Networks while Charles Dolan becomes executive chairman of the newly public company, while continuing his role as chairman of Cablevision. He stated: "As a separate public company, AMC Networks has the opportunity to further showcase each of its programming services and provide value to investors, distributors and advertisers."

The new AMC Networks include AMC, WE tv, IFC, Sundance Channel and AMC/Sundance Global, plus IFC Entertainment, an independent film business.

As part of the spinoff, AMC Networks refinanced $2.43 billion of new funded debt.

AMC stock dipped this morning on its first day of trading on Nasdaq, to $39.32. It closed yesterday at $43.50.