I believe the idea is that they are taking access to finance from the rich and giving it to the poor. Commissions are often flat dollar amounts, so the more mon

I believe the idea is that they are taking access to finance from the rich and giving it to the poor. Commissions are often flat dollar amounts, so the more money you have, the less significant they are. Charging a percentage (which this is effectively doing) benefits small trades and hurts large ones. And I believe they still meet or beat market rates, they just find savings that they don't pass along to the traders. No doubt the Robin Hood of myth turned a profit as well.