Despite rocky action, the S&P 500 has rallied 1.5% in the fourth quarter. A number of industry groups have done much better than that. But many others have fared much worse. The strongest is the Diversified Operations group, which jumped 28% through Friday. Conglomerates such as Berkshire Hathaway (BRKB), 3M (MMM) and DuPont (DD) are a few of the top-performing stocks in the group.