Warren Buffett's Berkshire Hathaway was an aggressive buyer of stocks in last year's fourth quarter, nearly quadrupling its stake in Apple and increasing its stake sevenfold in the four biggest U.S. airlines.
In a regulatory filing, Berkshire reported owning 57.4 million shares of Apple as of Dec. 31, which would now be worth $7.74 billion, up from just from 15.2 million shares in the iPhone maker three months earlier.
It also disclosed new stakes in satellite radio company Sirius XM and seed company Monsanto, which is being bought by Germany's Bayer.
Though it is unclear who make which investments, the filing appears to reflect much of the $12 billion of stock that Buffett said he had bought between the Nov. 8 Presidential election and the end of January.
Larger Berkshire investments such as Wells Fargo, Coca-Cola and International Business Machines are normally Buffett's, but the 86-year-old billionaire has given his deputies Todd Combs and Ted Weschler more to invest over the years.
Berkshire's initial investment in Apple got attention last year, given Buffett's usual aversion to technology companies — apart from IBM — which he considers outside his zone of competence.
The new, larger stake makes Berkshire one of Apple's 10 biggest investors.
"I'm stunned to see the size of that Apple position," said Thomas Russo, who oversees $11 billion of assets, including 12 percent in Berkshire, at Gardner Russo & Gardner in Lancaster, Pennsylvania.
Berkshire did not respond to a request for comment.
The Omaha, Nebraska-based conglomerate also owns roughly 90 companies such as the BNSF railroad, Geico car insurance and Dairy Queen ice cream.
Its Class A shares closed on Tuesday up $2,078.95 at $250,419, a record high closing price and less than 0.2 percentage points below its all-time high on Dec. 14.