It looks like the prevailing explanation is that DTCC increased collateral requirements and some brokers couldn't handle that. https://www.bloomberg.com/opinio

It looks like the prevailing explanation is that DTCC increased collateral requirements and some brokers couldn't handle that. https://www.bloomberg.com/opinion/articles/2021-01-29/reddit-traders-on-robinhood-are-on-both-sides-of-gamestop https://www.bloomberg.com/opinion/articles/2021-01-29/reddit...