Berkshire halved its stake in Apple in the second quarter, holding $84.2 billion in the company's stock, down from the $174.3 billion it owned at the start of the year. The sale could cost Berkshire somewhere in the range of $15 billion in taxes this year.

Despite the selloff, Buffett has assured investors and followers that he's in it for the long haul with Apple and some of his other major holdings.

"Unless something really extraordinary happens, we will own Apple, and American Express, and Coca-Cola when Greg takes over this place," he said during a question-and-answer session at the annual Berkshire shareholder conference in May, referring to Greg Abel, his handpicked successor.