In a heated debate, Facebook shareholders argue whether social media has peaked

  • An investor and an analyst took polar opposite positions on Facebook.
  • Facebook shares have dropped 11 percent this week.

Investment manager Ross Gerber thinks Facebook is in deep trouble after the Cambridge Analytica data leak.

On CNBC's "Closing Bell," Gerber argued that "social media has peaked" and predicted that "daily active users in the North American region in Facebook will decline in this quarter, and will continue to decline, and the fact that they have Instagram is the only thing that's saving them right now."

Ian Winer, an analyst at Wedbush Securities, strongly disagreed, saying "the fundamental business, the fact that 2 billion people use this service, where else are advertisers going to go?"

The debate got heated when Gerber accused Cambridge Analytica of being responsible for deaths in Kenya. Later on Twitter, he referenced a BBC article about the firm boasting about influencing last year's Kenyan elections. The elections were marred by violent protests.

Facebook shares have plunged 11 percent this week, following revelations on Friday that Cambridge Analytics misused the data of over 50 million users.