The crowd of companies in this section [Manufacturing, Service and Retailing Operations] sells products ranging from lollipops to jet airplanes. Some of these businesses, measured by earnings on unleveraged net tangible assets, enjoy terrific economics, producing profits that run from 25% after-tax to far more than 100%. Others generate good returns in the area of 12% to 20%. A few, however, have very poor returns, a result of some serious mistakes I made in my job of capital allocation. I was not misled: I simply was wrong in my evaluation of the economic dynamics of the company or the industry in which it operated.
—Warren Buffett, Letter to Shareholders 2013