here James @JGenThree · 11m Replying to @rockstar_stocks and @AntonioTheMexi - Securities can't be "borrowed" more than once - Some securities won't be able to be used as collateral - Short/naked options selling or buying won't be possible: HF will need to have the shares when buying puts or selling calls.
and
Replying to @AntonioTheMexi for all those asking this allows banks to force automatic margin calls. hedgies are done