Stocks making the biggest moves after hours: Facebook, Ollie's Bargain Outlet & Viacom

Mark Zuckerberg, CEO of Facebook.
Jaap Arriens | NurPhoto | Getty Images
Mark Zuckerberg, CEO of Facebook.

Check out the companies making headlines after the bell:

Shares of Facebook gained nearly 3 percent post-market. The social media company announced a slew of new privacy measures on Wednesday afternoon that restrict third-party access to personal user data. The new measures come after a series of criticisms regarding the company's handling of personal user data and the millions of users whose data was used by Cambridge Analytica without permission.

Ollie's Bargain Outlet stock fell more than 4 percent after hours. The retail chain reported earnings and revenues that beat Wall Street estimates, but mixed guidance sent shares falling. Same-store sale guidance for the upcoming year was weaker than analysts expected and other 2018 guidance was mixed.

Viacom shares rose 1.3 percent in extended trading amid fights over leadership with CBS. Viacom rejected CBS' lowball bid, sources say, and is now planning a counter offer.