Investing to boost crude output rewards oil majors with glut, slim profits

(Reuters) - The world's largest oil companies invested billions of dollars to boost crude production and their success has turned around and bit them -- and their shareholders. Oil majors Exxon Mobil Corp , Chevron Corp and Royal Dutch Shell all reported earnings on Thursday and Friday that showed key units significantly underperformed, particularly refining and chemicals. Investor discontent with weak returns, previously concentrated on smaller shale companies or oil services firms, has..