Warren Buffett's Berkshire Hathaway Inc. increased its stake in Wells Fargo & Co., building equity holdings amid a markets decline that the billionaire investor said provided an opportunity for buying stocks "on sale."

Buffett's firm added 9.7 million shares of the biggest U.S. home lender in the three months ended June 30, boosting the holding by 2.8%, Omaha, Nebraska-based Berkshire said this week in a filing that listed its U.S. stockholdings. Berkshire accelerated purchases on Aug. 8 as the Standard & Poor's 500 Index plunged 6.7%, its steepest decline since December 2008.

"I like buying on sale," Buffett, Berkshire's chief executive officer and head of investments, said in a television interview with Charlie Rose to be broadcast on PBS. "Last Monday, we spent more money in the stock market buying than any day this year."

Buffett, 80, is spending on stocks and takeovers as near- record low interest rates limit returns in fixed income. Banks, facing tighter regulation, can "still be plenty profitable," Buffett said last month. San Francisco-based Wells Fargo, which counts Berkshire as its biggest shareholder, fell 12% in the three months ended June 30 and has slipped 11% in the current quarter.

The increase in the Wells Fargo stake cost Berkshire about $277 million, assuming purchases came at the bank's average trading price for the second quarter of $28.53 a share.

"It looks to me that he couldn't resist topping up," said Thomas Russo, a partner at Berkshire investor Gardner Russo & Gardner. "Stay tuned. If he liked it at the quarter's end, and he has as much cash as he had, there's no reason to think he might not have liked it more in the early half of August."

Wells Fargo rose 89 cents, or 3.7%, to $25.02 Monday in New York Stock Exchange composite trading, valuing Berkshire's stake at $8.8 billion. Wells Fargo, led by Chief Executive Officer John Stumpf, has slid 19% since Dec. 31, better than the 25% decline in the KBW Bank Index. Berkshire Class A shares have fallen 9.8 percent this year.

Berkshire also increased holdings in MasterCard Inc. by 88%.

Subscribe Now

Access to authoritative analysis and perspective and our data-driven report series.

14-Day Free Trial

No credit card required. Complete access to articles, breaking news and industry data.