Another cable company merger was announced today, but it won't be completed unless the government allows Comcast to buy Time Warner Cable (TWC).

Charter Communications plans to buy Bright House Networks for $10.4 billion, but the deal is contingent on Comcast's big merger. That's because Charter itself has a stake in Comcast/TWC; Charter stands to gain 1.4 million subscribers from Time Warner Cable in exchange for $7.3 billion. Comcast would also divest itself of 2.5 million subscribers with the spinoff of a new cable company called GreatLand Connections.

If the Comcast/TWC and Charter/Bright House mergers go through, Charter would end up as the second biggest cable operator in the US behind Comcast.

But all these deals could now be stopped if the Federal Communications Commission or Department of Justice blocks Comcast's purchase of Time Warner Cable. The Charter/Bright House merger "is subject to several conditions, including Charter shareholder approval, the expiration of Time Warner Cable's right of first offer for Bright House, the close of Charter's previously announced transactions with Comcast and regulatory approval," the merger announcement says.

Charter today is the fourth largest cable operator in the country (behind Comcast, TWC, and Cox) with 5.1 million Internet subscribers and 4.3 million pay-TV subscribers. Bright House is the sixth largest cable company with 2.5 million customers who subscribe to one or more of its services in Florida, Alabama, Indiana, Michigan, and California, according to the Charter/Bright House merger announcement.

(Bright House is owned by the Advance/Newhouse Partnership, which is part of Advance Publications. Advance Publications owns Condé Nast, which owns Ars Technica.)

Though Advance/Newhouse would give up control of Bright House, it would end up owning 26.3 percent of Charter (or "New Charter," as the announcement calls it). Charter would retain control of the other 73.7 percent.

The government's review of Comcast/Time Warner Cable is expected to last through the middle of this year.