BP crisis highlights issues with commodity-stock investing, says Threadneedle

Gold and oil have been high-profile news for very different reasons in recent months. Aside from a recent price lull, the precious metal has been attracting huge inflows as a safe haven from market turmoil. Meanwhile, just as BP appeared to have finally stemmed the Gulf of Mexico leak, another explosion -- this time in Dalian, China -- caused another oil spill, though admittedly of far smaller proportions. One thing these oil crises have shown is the difference between buying commod…