Move over, Howard Stern. There's a new king of all media.

Google's (NASDAQ:GOOG) (NASDAQ:GOOGL) YouTube could be worth as much as $550B, investment firm MoffetNathanson said on Monday, as the video-sharing platform became the largest aggregator of TV content in the U.S. last month.

“This ranking, which measures total TV viewing across both linear and streaming platforms, underscores YouTube’s dominance in capturing audience engagement, surpassing traditional broadcast (and cable) giants like Disney, Fox, Paramount, and NBCU, as well as streaming leader Netflix,” analyst Michael Nathanson wrote in a note to clients. “For this and several other reasons, we crown YouTube the 'New King of All Media.'”  

By last year, YouTube had become the second-largest media company by revenue, at $54.2B, behind only Walt Disney (DIS), Nathanson said. However, that's expected to flip-flop this year, with YouTube continuing to see boosts in engagement, and thus, revenue. 

And based on public competitors, a standalone version of YouTube could be worth anywhere between $475B and $550B, or roughly one-third of Alphabet's current valuation, Nathanson explained. He has a Buy rating and $210 price target on Alphabet.

Delving a bit deeper, Nathanson said that YouTube could become “the central aggregator for all things professional video,” and go after the $85B consumer pay TV market, as well as the roughly $30B streaming market in the U.S.

“On monetization, when comparing YouTube’s massive TV screen engagement to its estimated TV revenue, it remains significantly under-monetized relative to its scaled reach and differentiated offering,” Nathanson added. “This signals a substantial runway for improving its monetization strategy.”

Google shares were lower in midday trading on Monday.