awesome, thanks for all the info, this is great data
Also - anyone know if it's possible to get commissions down to a reasonable level on any exchanges for automated trading?
The gox rate of 0.60% is way too high for what I'm doing ( it would eat all the profit and then some from each trade ).
If I can get the commission down to 0.1% or below then I can make money.
Note that gox only charges on one side of the trade (don't remember which). So if you're trading both directions, the effective rate is half what's posted. If you do a lot of volume & can get past the critical 10000BTC/month number, you can get it down in the vicinity of 0.15%.https://mtgox.com/fee-schedule
In my experience, even at such rates, automated market making on gox is highly competitive and I wouldn't be surprised if it's negative expectancy in the long run (a lot of gung-ho people who see a small profit every day but don't account for tail risks). But if you know what you're doing, as you sound like you do, you might be able to make a small profit.
Bitfloor has better rates (including rebates for providers), but their volumes are crazy low.
I guess I should PM the exchanges and see if they'll make an exception for someone who makes the market ( provides liquidity ) exclusively and who trades frequently.
There are some exchanges out there that do this sort of deal-making. CampBX comes to mind. I think it hurts the exchange in the long run, because people are suspicious of an exchange providing special treatment to a non-disclosed set of members. I also think you'll find mtgox and the other highish-volume exchanges want to stick to what's posted. If you find out otherwise, I'd be interested to hear about it
If you want to make some money and have access to low-commission currency exchange, I would draw your attention to cross-exchange-cross-currency arb. It's hard to do (mostly because of old-world financial red tape), and that makes it much less competitive.