Quote from bone:
Spreads were a great mean reversion trade (convergence) from the late 90's until about 2006. It is a directional divergence trade in a big way now. I have a mechanical trading model for the entry points, and I provide it both in chart technical study format and the custom programmed scanner format to clients. Most usually use both scanner and charts simultaneously, since we have so many different spread combinations in every market space which we have to monitor. So, pure mechanical entry. The trade position exits are rules-based by design.
For all practical intents and purposes, I suppose that we are 'gray box' traders.