By Trevor Hunnicutt and Jonathan Stempel
NEW YORK (Reuters) - Warren Buffett, the billionaire chairman of Berkshire Hathaway Inc (N:BRKa), on Thursday said the conglomerate has bought back its own stock for the first time since 2012 and has added a "little" to its already huge stake in Apple Inc (O:AAPL).
Buffett also said investors are better off owning a basket of stocks than 30-year bonds and other fixed-income securities as a strong U.S. economy bolsters corporate profits despite higher costs from tariffs, which have also affected Berkshire.
"I don't know when to buy stocks, but I know whether to buy stocks," Buffett, celebrating his 88th birthday, said on CNBC television.
"Business is good across the board," he added. "It was good two years ago, it keeps getting better."
Berkshire has more than 90 businesses in the insurance, energy, food and retail, industrial, railroad and other sectors, and invests in companies such as Apple, Wells Fargo & Co (N:WFC), Bank of America Corp (N:BAC) and Coca-Cola Co (N:KO).
A buy-back policy announced on July 17 gave Buffett, who has gone 2-1/2 years since a major acquisition, a new way to deploy Berkshire's $111.1 billion of cash and equivalents.
Berkshire said the policy would free Buffett and Vice Chairman Charlie Munger to repurchase stock when the price was below Berkshire's "intrinsic value," a determination that would be made "conservatively."
Berkshire's old policy forbade buybacks unless the price exceeded 1.2 times book value per share. The Omaha, Nebraska-based company recently traded at around a 1.45 times multiple.
Buffett said "we've bought back a little" stock since the change, and that he and Munger need "a big enough discount" to ensure that long-term shareholders are better off.
Berkshire has also bought "just a little" more Apple stock since June 30, he said, when it had a 252 million share stake now worth more than $56 billion.
Buffett is also a happy Apple customer.
He said he uses his iPad "a lot," and that the iPhone is "enormously underpriced" even when it costs $1,000, given how indispensable it has become for so many people.
Buffett was speaking from the Smith & Wollensky steak house in Manhattan, where he planned to eat lunch with the person who in June agreed to pay $3,300,100 at an annual charity auction.
Proceeds benefit the Glide Foundation, a San Francisco charity that serves people who are poor, homeless or battling substance abuse. The winning bid was the third-highest in 19 years of auctions, which have raised $29.6 million.