I've used both Neovest "First Alert" (major bugs!) and Tradestation 6 for pair and merger spread charts...I'm looking for a new platform now. Anybody have experience with good charting/analysis software for creating spread charts?
Qcharts is pretty good. Can give some problems if you have a lot of spread charts up that include more than one math operator. I've had dozens of them open at once with no problem when displaying them as ratios (one divided by the other). And it's cheap, $80 a month I think. I've also used FirstAlert and I think Qcharts does better spreadcharts, and is way better than AT Financial.
After much trial and error with many programs (including those mentioned here), I use Sierra charts with IB data for all ratios/spreads and have constructed well over 300 custom ratio charts. Has been very reliable and easy to customize (through Sierra's worksheet application). Amazing this software doesn't cost more.