I mentioned that I would get around to reading Financial Armageddon while we were here; I've knocked out a little more than half and my thoughts so far are holy cow!As I was reading today I had a thought about sector weightings and when to cut back.I thought of Tom Lydon's rule of thumb about using the 200 DMA as a point to get out; for clarification I use the 200 DMA of the broad market as a catalyst to start taking defensive action.I then realized that I haven't made too many sector weight changes in the last couple of years; this does make some sense as the market has only been up a little. The two that come to mind have been with energy and emerging markets ...