it s really a casino atmosphere there. reporter: but companies like amc and gamestop saw their stocks shoot back up, with amateur investors buying again after platforms like robinhood lifted restrictions. this man jumped right in. it s a really, really weird time we re living in. i had never thought i would invest in stocks casually like that, but i saw the opportunity, downloaded the app on my phone, and did it. reporter: the newcomers going online to talk on reddit and trade on apps like robinhood. they ve spent weeks buying up shares in c ges the s.e.c. will probably look at two things. one, to what extent do platforms have some sort of obligation to warn or to educate new investors about the risks of investing in these types of stocks? and two, does this type of