Berkshire Hathaway has added a large chunk of Apple stock to its portfolio.
The multi-billion-dollar conglomerate, which is run by legendary investor Warren Buffett, increased its stake in Apple by 55 percent as of June 30. Apple's stock has been on a tear lately, rising about 21 percent over the past three months.
Berkshire's stake in Apple was first revealed in May. It wasn't Buffett himself who made the initial purchase, but rather one of portfolio managers.
AAPL 3-month chart