(CNN) - CBS and Viacom are merging to become ViacomCBS Inc., they announced Tuesday.
The long-awaited deal between the two media giants puts some of the biggest brands in entertainment back under one corporate banner.
Those brands include CBS' broadcast network, the streaming service CBS All Access, movie studio Paramount and cable networks like Showtime, MTV, Nickelodeon, BET and Comedy Central.
The all-stock merger creates a company with more than $28 billion in revenue.
Bob Bakish, the current CEO of Viacom, will become CEO of the new company. Joe Ianniello, acting chief executive of CBS, will become chairman and CEO of CBS.
"Today marks an important day for CBS and Viacom, as we unite our complementary assets and capabilities and become one of only a few companies with the breadth and depth of content and reach to shape the future of our industry," Bakish said in a statement on Tuesday.
The merger is a reunion for CBS and Viacom. The two companies used to be one, but split in 2006. Shari Redstone, the president of CBS's parent company National Amusements, has been trying for years to reunite the two. Her efforts were initially stymied by former CBS chief Les Moonves, who left his role last September amid a flurry of sexual misconduct allegations against him.
"I am really excited to see these two great companies come together so that they can realize the incredible power of their combined assets," Redstone said in a statement on Tuesday. "My father once said 'content is king,' and never has that been more true than today."
The deal comes during a volatile period in the media industry. Multiple other companies have done similar deals in an attempt to gain scale and combat challenges from digital-native rivals. Disney bought much of what was once 21st Century Fox, for instance, and AT&T purchased Time Warner — now WarnerMedia — including CNN. Disney, WarnerMedia and other legacy media companies are also debuting new streaming services in the coming months in part to compete with Netflix and Amazon.
The merger of CBS and Viacom will "create the second largest player in US TV advertising" and the improved scale of the companies could create a stronger negotiating position with third parties, according to research firm Moffett Nathanson.
"CBS's and Paramount's production asset will quickly move up the ranks to challenge the big boys of Disney, Comcast, AT&T and Netflix and will be an attractive home for creative talent," Moffett Nathanson analysts said in a note to clients on Friday.
The announcement comes after weeks of media reports and rumors regarding negotiations between CBS and Viacom. The companies' stocks both jumped when the merger talks were reported in late May.