Warren Buffett outperformed the S&P 500 for decades, but those days may be over. Berkshire Hathaway has basically matched the return of the S&P 500 since 2011. At current levels. Buffett thinks Berkshire has only a "tiny" chance of outperforming the S&P 500 over the long-term. Watch Berkshire Hathaway trade live. Legendary investor Warren Buffett, who has beaten the S&P 500 index for decades, has long predicted that his days of outperformance would be numbered given the growing size of his firm, Berkshire Hathaway.