Thanks, this is very helpful. Good points on where to report cost basis. I have a bunch of non-covered proceeds on my various 1099-B's, so I think proceeds will mismatch anyway from what's reported to the IRS (although I'm attaching the 1099's to the return). But I guess that's irrelevant to this discussion. I think you're right - I'll just do the Schedule C with no income, it should be pretty clear that it is for TTS with business code 523000 and the tens of thousands of trades reported on 1099s.
