Instead of building out its own streaming service the way rivals Walt Disney, NBC Universal and AT&T's WarnerMedia are doing, Viacom is acquiring one.

The company, whose networks include MTV, VH1 and Comedy Central, agreed to purchase Pluto TV, the free TV streaming service, for $340 million in cash.

Pluto, which was founded in 2013, streams more than 100 channels and is ad-supported. The service boasts more than 12 million monthly active users.

Viacom said the acquisition will not only expand its presence in next-generation distribution platforms, but will also grow its advanced advertising business. It can do this by adding "billions of high-quality addressable advertising impressions" and bringing in an audience that is young, gender-balanced and hard to reach, the company said in a statement.

"As the video marketplace continues to segment, we see an opportunity to support the ecosystem in creating products at a broad range of price points, including free," Viacom President and CEO Bob Bakish said in a statement. "To that end, we see significant white space in the ad-supported streaming market and are excited to work with the talented Pluto TV team, and a broad range of Viacom partners, to accelerate its growth in the U.S. and all over the world."

The deal also could help Viacom acquire and retain consumers for its current subscription products, like the children-focused Noggin and Comedy Central Now, and serve as a new distribution outlet for Viacom Digital Studios.

Pluto TV stands to benefit by beefing up its library with content from Viacom. But the company added that its current programming will remain in the pay-TV ecosystem on its networks.

Tom Ryan, Pluto TV CEO and co-founder, will continue to serve as CEO of the company, which will operate as an independent subsidiary of Viacom after the transaction closes. The deal is expected to close in the first quarter of 2019.