Actually, I think they charge an additional fee when you sell of between .01 to .03 total, which is pretty good, because ChoiceTrade adds a fee whenever you sell of like .00015 per share, but only up to $3.76, so with the $5 commission, a sell of millions of shares costs $8.76 total. Etrade's commission of $9.99 - $12.99 is already higher than that, but there are no more fees. I've bought and sold many, many millions of shares and never paid additional fees. The highest commission when I sold was $13.02.
News 
Market Data 
Discover 
