Losch Management - Client Letters - September 2005: "Bill Gates
During the week of September 5 to September 9, Bill Gates purchased 260 shares of Berkshire Class A stock. This brings his total holdings to 3,540 shares, with a total value of $296 Million."
He must have read the article about Berkshire's intrinsic value being way higher than current stock price. Either that or he lost a bet with Warren.