The idea is that if you create a synthetic currency by buying or selling various portions of other currencies, to create a synthetic that matches the characteristics of your trading system better than any one currency could. For example if you have a mean reversion trading system, you create a synthetic currency that has stronger mean-reversion tendencies in the timeframe you want to trade than an individual currency would. An example of someone experimenting with this idea can be found here: http://www.forexfactory.com/showthread.php?t=262827 I suppose you could try this with stocks as well as currencies. I'm hoping some members of the ET community will comment on the theoritical validity, or lack thereof, of this approach. Are there any glaring flaws you see in the idea? Has anyone else experimented with it?