Warren Buffett, who announced he's retiring as CEO of Berkshire Hathaway, built an institution where long-term thinking, autonomy and culture guide every decision. (Photo by J. Countess/Getty Images) ...

Warren Buffett started out by identifying opportunities in undervalued companies. Later, his strategy was buying a company that would get bigger on its own. We look at that second phase of his career.

Warren Buffett is seen at The Women’s Conference in Long Beach, Calif., in October 2008. His lengthy biography by Alice Schroeder is “The Snowball: Warren Buffett and the Business of Life.” (AP file ...