Because Apple is the largest company by market value, its moves can ripple through the broader market, including the technology-laden Nasdaq index. Berkshire is, however, scheduled to release its first-quarter earnings report during the gathering.
"It is an unbelievable company", Buffett said, according to CNBC. It's always a colorful event, with CEO Warren Buffett putting on a show that is doubtless the most fun among major USA companies' investor events.
Berkshire Hathaway Inc. operates as a holding company.The firm is worth $477.10 billion.
His endorsement helped lift Apple stock to a record high during trading on Friday.
The Apple purchase, costing between $11 billion and $14billion, adds to the nearly 170 million shares that Buffett-run Berkshire Hathaway owned at the end of 2017, when it was already his biggest shareholding.
Quarterly earnings per share rose 30% to $2.73, ahead of analyst projections of $2.67.
Berkshire had $116 billion in cash at the end of a year ago, so has plenty of spare money to make big investments.
There's no denying the fact that Apple is still leading the tech world, having sold 52.2 million iPhones and achieved profit of $13.8 billion at the start of the year.
The billionaire investor recently sold out of an unsuccessful investment in International Business Machines (IBM), at the same time he was buying Apple.
With about 5.07 billion shares, Apple stock would need to hit 197.24 to claim a $1 trillion market cap.
There may also be another reason for the investment: Berkshire's cash pile of $116 billion. Of the 45 stocks listed on the company's year-end 13F form, 27 are down so far in 2018. While the trade tensions have rattled investors, many market watchers think the two sides will eventually come to a deal that doesn't disrupt trade much.