Investor Warren Buffett says his company bought about $10.7 billion of IBM stock this year, giving him a stake of more than 5 percent stake in the technology company.

Buffett revealed the new investment during an interview on CNBC Monday. Buffett’s company, Berkshire Hathaway Inc., will file a full quarterly update on its U.S.stock portfolio Monday afternoon.

Buffett said executives at IBM were unaware of the purchases, and that he’d never spoken to the company’s chief executive officer, Sam Palmisano.

“They’ve done an incredible job” in laying out a roadmap for the future, Buffett said on CNBC.

The new stake in the company marks a massive change for Buffett, who has famously eschewed tech stocks despite a long, close friendship with Microsoft co-founder Bill Gates, who sits on Berkshire’s board.  Buffett said he’d gained added insight on IBM in reviewing the company’s regulatory filings, and said he’d been “hit between the eyes” by the advantages the company enjoys in finding and keeping clients.

“It’s a company that helps IT departments do their job better,” Buffett said on CNBC. “It is a big deal for a big company to change auditors, change law firms,” or for IT departments to move away from using IBM, he said. “There is a lot of continuity to it.”

Berkshire bought about 64 million shares since March, or about 5.5 percent of IBM. Buffett says he believes IBM has a sound plan for the future. IBM shares rose $1.78 to $189.16 in pre-market trading after jumping as high as $190.55 earlier.

Buffett said Berkshire paid an average of about $170 per share for the IBM stock.

Berkshire’s investments are closely watched in the market because of Buffett’s successful record. Buffett has said that Berkshire has been buying aggressively during the recent market turmoil.

Buffett, who put $5 billion into Bank of America earlier this year, comes up whenever there is talk of a large European bank needing to raise capital, particularly in the current environment of write downs on sovereign debt.

But he told CNBC that he would need to understand European banks better before investing in them, and that he has not yet seen an investment opportunity there in which he wants to take part.

The “Oracle of Omaha” and Berkshire Hathaway chief executive said he expects Europe’s economy to show improvement 10 years from now, but getting there will be difficult.