OMAHA, Neb. (AP) — Investors might question Warren Buffett's long-standing aversion to tech stocks after his Berkshire Hathaway bought 9.8 million shares of Apple.

Buffett has always avoided technology companies because he said it was too hard to pick which ones would prevail long term, although he made an exception to that rule to buy a major IBM stake in 2011.

Buffett was also reported to be considering joining a bid to acquire Yahoo. But Buffett told CNBC Monday he would only act as a potential financing partner for Quicken Loans founder Dan Gilbert's bid.

Berkshire revealed the new Apple investment Monday in a filing with the Securities and Exchange Commission detailing a number of changes to its $129 billion portfolio.

The new investment might have been made by Berkshire's two other investment managers.