Warren Buffett reportedly traded millions of dollars worth of stocks that Berkshire Hathaway was buying and selling

• ProPublica reported Thursday that Warren Buffett may have violated Berkshire Hathaway's ethics policies.
• Leaked IRS data seen by ProPublica showed that Buffett sold shares in stocks that Berkshire was trading.
• Buffett has previously said that trading the same stocks as Berkshire would pose a conflict of interest.

Legendary investor Warren Buffett may have violated Berkshire Hathaway's ethics policies — which he himself wrote — by personally trading the same stocks as the conglomerate, according to a ProPublica report on Thursday.