Cablevision Systems Corp has agreed to be purchased by European telecommunications company Altice for $17.7 billion, including debt, a source familiar with the matter told Reuters ahead of an official announcement. Shares of Cablevision, which is controlled by New York’s Dolan family, jumped 16 percent to $33.12 after the bell on Wednesday. Altice will pay $34.90 per share for Cablevision, CNBC said, citing sources.