[wocram]

This is not true, Citadel is the largest market maker and is in fact TDA's largest broker. This is abundantly clear in 606 disclosures.

TDA: https://www.tdameritrade.com/retail-en_us/resources/606_disc... from https://www.tdameritrade.com/disclosure.page

Webull: http://public.s3.com/rule606/webull/606-BULL-2019Q4.pdf from https://pic.webull.com/PDFs/Disclosure%20of%20Payment%20for%... / http://public.s3.com/rule606/webull/

Robinhood: https://cdn.robinhood.com/assets/robinhood/legal/RHS%20SEC%2... from https://robinhood.com/us/en/about/legal/

Fidelity: https://clearingcustody.fidelity.com/app/literature/item/990... from https://clearingcustody.fidelity.com/app/item/RD_13569_21696...

[hardwaresofton]

I stand corrected -- thank you for clearing this up, this completely explains it.

It does not explain why Fidelity allowed purchasing the stock however though, which means I was likely wrong about the link altogether. Thanks for pointing that out.

[EDIT] - Is it reasonable to assume that maybe TD and Fidelity have a venue that the others do not have and that's the reason? When I compare RH, WeBull, Fidelity and TD I see UBS Securities, LLC as the standout difference.

Was UBS choosing to route the orders (I guess they have none of the shorts on their books? or they properly managed their risk?) while the others didn't touch it?

[wocram]

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...