If strength in stocks rotates from one sector to another over time, why can’t we invest in sector X while it’s strong, sector Y when it’s strong and so forth? The answer is that sector strength changes unpredictably, and concentrating in a given sector when that sector is already overpriced is risky. When sanity breaks out, we don’t want to be in overpriced investments poised for a tumble. The best that investors can do (in all types of markets) is to take advantage of bargain prices and practice patience. Based on history, this approach is more apt to work to our advantage than trying to jump from sector to sector in pursuit of sometimes fleeting—and always unpredictable—changes in investor sentiment.