Robinhood, a trading platform favored by millennials, has locked out users from buying stocks including GameStop, Nokia, and AMC.

The news follows a Reddit community, WallStreetBets, causing the various stocks to skyrocket. Now, however, Robinhood’s move to ban users from purchasing shares in the three companies will likely drive the price down.

When platform users go to the profiles of stocks including GameStop, Nokia, and AMC, they are either met with a message that “this stock is not supported on Robinhood” or “you can close out your position in this stock, but you cannot purchase additional shares.”

As a result, Twitter users have begun calling to “boycott Robinhood.”