Comcast Corp. said yesterday it would buy Time Warner Cable Inc for $45.2 billion in an all-stock deal that combines the two largest US cable operators.

The friendly takeover comes as a surprise after months of public pursuit of Time Warner Cable by smaller rival Charter Communications Inc., and immediately raised questions as to whether it would pass regulatory scrutiny.

Comcast will pay $158.82 per share, which is roughly what Time Warner Cable demanded from Charter.

The combined company would divest three million subscribers, about a quarter of Time Warner’s 12 million customers. Together with Comcast’s 22 million video subscribers, the roughly 30 million total would represent just under 30 per cent of the US pay television video market.

The new cable giant would tower over its closest video competitor, DirecTV, which has about 20 million video customers.

If successful, the deal will be the second time in little more than a year that Comcast has helped reshape the US media landscape after its $17 billion acquisition of NBC Universal was completed in 2013.

The proposed combination, which would give roughly 23 per cent of the merged company to Time Warner Cable shareholders, is subject to regulatory approval and the two companies expect to close the deal by the end of the year.