In an unusual and personal announcement, Mr. Buffett said the resignation followed revelations that Mr. Sokol had purchased roughly $10 million in shares of a chemicals company that Berkshire recently agreed to buy at the suggestion of Mr. Sokol, Lubrizol Corp.
Mr. Buffett said Mr. Sokol, 54 years old, had bought 96,060 shares in January, before Berkshire reached a $9 billion deal to acquire the company. Berkshire's purchase price of $135 per share meant that Mr. Sokol's stake rose $3 million in value.
Mr. Buffett said he and Mr. Sokol didn't feel the Lubrizol purchases were "in any way unlawful."
The SEC is reviewing the Berkshire press release and considering whether to launch an investigation, a person familiar with the matter said Wednesday.