Advertisers for the first time must now decide whether putting content on Facebook represents a liability, tech analyst-turned-venture capitalist Gene Munster told CNBC on Wednesday.

"I don't think there's going to be some huge aversion from Instagram or Facebook. I think that those platforms are going to be around forever," Munster said in a "Squawk Box" interview. "But I do think the lift you're going to see from these policy changes can impact their advertising effectiveness."

"We've seen a couple small advertisers ... back off from the Facebook platform. But it's subtle things like that" that makes investors watch the stock, Munster added.

Munster, founder of Loup Ventures, which focuses on research and early-stage funding, said he doesn't expect Facebook's stock to fall sharply, but shares could be a "stuck in the mud" for the next six to 12 months.

Shares of Facebook have declined more than 17 percent from the close on March 16 through Tuesday's close. On March 17, The New York Times, The Observer and The Guardian reported that Cambridge Analytica had harvested data from more than 50 million Facebook users without their permission. The profile information was used for targeted political ads.

On Monday, the Federal Trade Commission confirmed that it's investigating the company's data practices.

Facebook unveiled changes Wednesday to its data and privacy tools. Among the changes: The settings will now be on a single page, rather than spread across nearly 20 different screens.

Additionally, Facebook chief Mark Zuckerberg has agreed to testify before Congress on the leak and the company's data practices.

On Tuesday, Christopher Wylie, the Cambridge Analytica whistleblower, told U.K. lawmakers that the election of Donald Trump prompted him speak out. The political analytics firm worked on the Trump presidential campaign.