I'm not sure but I remember reading iHub posts stating that Ameritrade routes through AUTO. Have you checked out Interactive Brokers? I like them a lot - low commissions (usually $1 - $2.75 or so, more often $1), nice interface, and they let you route through ARCA if you choose. Only downside is that often on stocks moving from the Greys to the Pinks or reactivating after long dormancy, they aren't in IB's database until you contact them through their online help ticket system. They've gotten a lot faster at getting the desired ticker into the database within 1 or 2 days. It used to take 3 or 4 days. Once it's in the database you can trade it. It's very, very rare that they won't allow you to trade whatever you want to trade. I use MyTrack and Scottrade for my backups. Scottrade's got a great, free news alert system. But as we all know, in other areas they suck big time. LOL.
