A portfolio with the greatest possible diversification benefits can be built by owning about two companies from each of these classifications. Here's an example. I've selected companies with low-ish price-to-earnings (P/E) ratios and high-ish returns on equity (ROE) relative to the industry averages. That combination of factors has historically produced better-than-average returns:
GICS Company P/E ROE
Energy Hess (NYSE: HES) 17 20%
Materials DuPont (NYSE: DD) 15 29%
Industrials Gehl (Nasdaq: GEHL) 9 10%
Consumer Discretionary Vector Group (NYSE: VGR) 15 75%