"GameStop and AMC trading restricted by TD Ameritrade, Schwab, Robinhood others "
https://www.msn.com/en-us/money/personalfinance/gamestop-and...
"Some users are experiencing issues with trading platforms Vanguard, TD Ameritrade, and Charles Schwab due to heavy volume"
https://www.businessinsider.in/tech/news/some-users-are-expe...
Not to mention that the market is made up of all platforms and several of them were downright prohibiting GME buying. Some are listed in the article. Robinhood alone has more than 13 million users.