I think Kasey is right.
As to the question of larger spreads. I worked for Knight before they got into trouble.  Robinhood does only stock trading and there is not much spread payments coming form  it these days. Its so small these days, its not worth a lot.  No matter what its not enough to give away trades. 
And these firms pay somewhat the same to all companies.<p>Robinhood is a fascinating scheme of some sorts in my opinion. They will have to raise money from new VC investors to make commission payments. They need to be raising more money. This app will continue as long as they raise money and the VC money feed continues. For the sake of its employees, I hope the feed continues.<p>&quot;so I am &quot;out&quot;. ( Shark Tank :))