Comcast is laying the groundwork to divest nearly four million subscribers as part of its efforts to appease antitrust regulators scrutinizing the proposed acquisition of Time Warner Cable.
In one likely situation, Charter Communications, which had been trying to acquire Time Warner Cable, would become both a buyer and partner to Comcast.
In the first part of a proposed deal, Charter would buy about 1.4 million subscribers from Comcast, according to people briefed on the matter.
At the same time, Charter would swap some subscribers with Comcast, including those in the Los Angeles area. Comcast is buying Time Warner Cable’s roughly 1.8 million subscribers in the Los Angeles area, and gaining Charter’s subscribers in the area would complete its footprint there.
Comcast would also spin off a new public company with about 2.5 million subscribers, these people said. Charter would have a minority stake in this new company, and the rights to acquire more control over time.
But Charter would not have any operational control over the new company, these people said. Nor would Charter contribute any subscribers to the new company, which would have its own management team.
Together, the sale of subscribers and a spinoff is expected to deliver $18 billion to $20 billion to Comcast, cash that  it could use to buy back shares and pay down the debt it will take on to complete the deal for Time Warner Cable.
The deals have not been finalized and could still fall apart. Comcast and Charter were in discussions about a joint bid for Time Warner Cable in January, but negotiations between the two companies fell apart. And since Comcast and Time Warner Cable agreed on the sale, Charter has come out against the deal.
Comcast is also in talks with other interested buyers, including Cox Communications and private equity firms, these people said. The deals involving Charter, however, are the most likely to succeed at this point, they said.
The Financial Times reported on Friday that Comcast and Time Warner Cable were having negotiations with Charter. Earlier on Tuesday, Bloomberg News reported details on a possible swap and spinoff.
