I read that analysis when it came out. I'm not sure how accurate it is... in the end Robinhood still needs to make money since they aren't charging the typical per trade commissions.
You can probably back out what the HFTs margin is on this stuff by looking at public financials... KCG was public for a while.
You can probably back out what the HFTs margin is on this stuff by looking at public financials... KCG was public for a while.