Comcast will announce the launch of the cable networks on Wednesday, a source told CNBC

Comcast is moving ahead with the evolution of its cable network channels, people familiar with the matter told CNBC on Tuesday.

The separation is expected to take about a year, and an announcement from the company could come Wednesday, the people said.

The new structure will be led by Mark Lazarus, the current chairman of the NBCUniversal media group, one of the people said. NBCUniversal Chief Financial Officer Anand Kini will serve as CFO and chief operating officer of the new business, the person said.

Comcast Chairman and CEO Brian Roberts will retain a voting position at the company, but will not serve as an executive or on the board of directors, the person said.

The spinoff will be tax-free and the share structure of the new entity will be similar to that of Comcast, according to the person.

The company announced during its quarterly earnings call in October that it is considering divesting its cable networks. Comcast President Mike Cavanagh said the company is looking to create “a new company, which is financially sound for our shareholders and combines our strong portfolio of cable networks.”

Comcast is moving forward with the decision as millions of customers switch from traditional pay TV bundles to streaming. The company has been developing NBCUniversal’s Peacock streaming platform in recent years.

Shares of Comcast rose more than 2% in after-hours trading.

Networks that are part of the spinoff include E!, Syfy, Golf Channel, USA and Oxygen, a person close to the matter said. Bravo will remain part of Comcast’s NBCUniversal as its content is heavily exposed to Peacock, one of the people said.

Cavanagh had said in October that NBCUniversal’s broadcast network NBC and Peacock would remain with Comcast.

Although cord-cutting has impacted the business, traditional TV networks remain cash cows for media businesses. Comcast reported in October that third-quarter revenue in its media division, which primarily includes television networks, rose nearly 37% to $8.23 billion, largely due to the Olympics. Excluding the Summer Games, revenue was up about 5%.

The spinoff will take about a year as the company figures out what licensing deals need to be done, and whether MSNBC and CNBC will continue to work with NBC News, two of the people said.

The spinoff was first reported by the Wall Street Journal.

— CNBC’s Julia Boorstin contributed to this article.

This is the best news. Please refresh for updates.

Disclosure: Comcast owns NBCUniversal, the parent company of CNBC.