The Viacom investment was part of Roku’s latest $45.5 million round of funding, which the company disclosed last month in an SEC filing. That bought Roku to about $200 million raised to date.
Viacom confirmed the investment in Roku, reported earlier by Re/Code, but declined to provide further comment.
Viacom joins Roku’s other big-media backers, which include 21st Century Fox, Hearst, Dish Network and U.K. satellite provider Sky. In addition, the company is backed by Fidelity and venture-capital firms Menlo Ventures, Globespan Capital Partners and Luminari Capital.
While Roku has been contemplating going public, the latest round of funding indicates that it has for now opted to raise funds from private investors instead of launching an IPO.
In 2015, Roku users streamed 5.5 billion hours of content, up 73% from the year earlier, according to the company. It said it ended last year with 9 million monthly active accounts. In January, Roku said U.S. consumers have bought about 1 million TVs based on its streaming platform launching in the segment in 2014.
This year, Roku is projected to have 25 million U.S. users, representing 15.2% of connected-TV users, according to a forecast by research firm eMarketer. Google’s Chromecast will have 30.2 million users and Apple TV will have 20.5 million users in the States, per eMarketer estimates.