Altice NV, Patrick Drahi’s European cable operator, reached an agreement to buy Cablevision Systems Corp., according to people with knowledge of the matter, accelerating the company’s expansion in the U.S.

The agreement will be announced on Thursday, said the people, who asked not to be named before it is public. It values Cablevision, a cable TV and Internet service provider, at $34.90 a share, according to one of the people, a 22 percent premium over the target’s closing price of $28.54 on Wednesday in New York. Including debt, the deal will value Cablevision at $17.7 billion, the person said.

Adding Cablevision, a top-five U.S. cable provider, vaults Altice into the ranks of major pay-TV players in the market. The company agreed in May to buy majority control of St. Louis-based Suddenlink Communications in a $9.1 billion deal that marked the first U.S. foray by the French-Israeli billionaire Drahi.

Big changes in viewing habits are driving consolidation among pay-TV providers and spurring entertainment companies, their programming suppliers, to consider moves of their own. Cable and satellite TV in the U.S. suffered the largest subscriber losses ever in the second quarter, in part because of the popularity of web TV services like Netflix Inc. That’s threatening the industry’s two sources of revenue: ads and subscriber fees.

Cablevision, based in Bethpage, New York, advanced as much as 16 percent to $33.12 in extended trading on Wednesday. The shares were little changed in regular trading in New York. The company owns money-losing New York-area newspaper Newsday and TV station News 12, and Altice has committed to funding them, according to a person familiar with the matter.

Cablevision had 2.68 million video subscribers as of the second quarter, according to data compiled by Bloomberg Intelligence, while Suddenlink has about 1.14 million. The Wall Street Journal reported on Drahi’s talks with Cablevision earlier Wednesday, citing unidentified people.

Cablevision is controlled by the Dolan family, which holds about 72 percent of the voting power through Class B shares that have 10 votes each. The family also controls AMC Networks Inc. and Madison Square Garden Co., spinoffs from Cablevision.

The company was founded in 1973 by Charles Dolan, one of the pioneers of the cable TV industry. He started HBO before selling it to what was then called Time-Life. The 88-year-old billionaire is chairman of Cablevision, which is run by his 60-year-old son James, the chief executive officer.