Warren Buffett bets on Big Blue

OMAHA, Neb. - Investor Warren Buffett says he has been adding to his sizable stake in IBM (IBM) during the third quarter as shares in the tech company slide, and that his Berkshire Hathaway (BRK.A) has been spending about $500 million a week acquiring stock during recent market volatility.

Buffett appeared on CNBC Tuesday before dining with the winners of this year's auction of a private lunch. Beijing's Dalian Zeus Entertainment Co. paid $2,345,678.

Berkshire Hathaway recently disclosed a $4.5 billion investment in Phillips 66 even with energy companies being pummeled by low crude prices.

Buffett says he bases his investments on a company's prospects over the next five or ten years.

Buffett said Berkshire's $32 billion agreement to buy Precision Castparts hasn't slowed his other buying since it was announced last month.