Tastytrade also restricted trade in the same manner. They send a mail to all customers and made it very clear that it was Apex Clearing who forced their hand. It is very unlikely that something different happened at Robinhood.

No, I'm granting that as the parent's premise. And what liability reasons would Robinhood have to disallow buying an NYSE listed stock with 100% cash?

They've already been sued by retail investors who have lost their cash in the past and courts have already shown themselves to be somewhat partial to "the gamified interface just made me spend $1k I could barely afford because it was so fun!" arguments that RH is liable.

This is a much bigger deal, some (not hedge fund!) people are going to lose a crapton of money on it, and people are probably going to sue them once that happens.

You can see this discussed elsewhere in the thread.

> for liability reasons

For trying to get some positive media coverage, after being constantly bashed and blamed by them for the uneducated retail trader boom.