It's sort of in the middle. They have plenty of retail customers for sure, but they also have hedge fund and proprietary trader accounts. I doubt you would find a single hedge fund among Etrade customers.
> On what basis are you calling it most expensive though? It's much cheaper than any other brokerage I know when you look at fees holistically.
It's much cheaper than most retail brokerages. It's more expensive than firms that cater to professionals; for the most part those firms don't put their pricing on their website because they're individually negotiated with each customer. Some example firms: all the big banks, Apex Clearing, eRoom Securities, TJM Institutional Services. For the banks you're probably looking at a minimum $20 million account size just for them to accept you as a customer. The smaller players require $1-$5 million for decent rates, but might accept smaller account sizes.