A lot of meme stocks already had their 15 minutes, Tastytrade founder says

Tom Sosnoff, founder and co-CEO of trading platform Tastytrade, joins CNBC's 'Squawk Box' to discuss tumbling meme stocks. Sosnoff explains why he thinks meme stocks are "pretty much untradeable" right now because of the high capital requirements from the online brokerage firms that helped the shares take off.