When Warren Buffett, the CEO of conglomerate Berkshire Hathaway (NYSE: BRK.A)(NYSE: BRK.B), buys or sells a stock, Wall Street and investors tend to pay close attention. Since taking the reins, Buffett has created close to $670 billion in value for his shareholders (which includes himself), and he's led his company's Class A shares (BRK.A) to an almost unfathomable 20.1% average annual return. To put this performance in another context, the benchmark S&P 500 has "only" gained 30,209%, including dividends paid, since Buffett took over Berkshire Hathaway.