Markets were sent into yet another frenzy of activity today as hundreds of thousands of Robinhood and TD Ameritrade (UPDATE: WeBull, which many RH users were migrating too, has also halted new positions in these stocks) users woke up to find these brokers were no longer allowing any further trades on GameStop ($GME), as well as other notable 'meme' stocks like AMC ($AMC), BlackBerry ($BB), and Nokia ($NOK) as well as cryptocurrency Dogecoin which also started to take off late last night (UPDATE: WeBull, which many RH users were migrating too, has also halted new positions in these stocks).