In his Wall Street Journal article “All ‘Commodities’ Aren’t Equal,” Liam Pleven makes the simple point that the performance of broad-based commodities index exchange traded funds may vary significantly because of varying portfolio composition. The fungibility of commodities, or inaccurate advertising, may have led some investors to believe that commodity funds are fungible. They aren’t. The recent sell-off in commodities, particularly oil, drove that point home and “reinforced a painful lesson for some investors,” according to the article.