Warren Buffett has revealed that his investment company, Berkshire Hathaway, has bought a $1 billion stake in Apple.

In a regulatory filing, Berkshire Hathaway disclosed a holding of 9.81 million shares in Apple.

Warren Buffett, who has traditionally shied away from tech stocks, is known for buying “value stocks”, so it is being seen as significant for Apple.

Apple’s shares have fallen almost 30% over the past year but rose on May 16 and closed the trading session 3.7% higher at $93.88.

Slowing iPhone sales have led investors to question whether the company can maintain Apple’s huge profit levels.

Last week Apple temporarily lost its place as the world’s most valuable company after a fall in shares pushed its total market value below that of Google parent Alphabet.

Warren Buffett did not make the actual investment himself, meaning the order would have been placed by his stock-picking team Todd Combs and Ted Weschler, the Wall Street Journal reports. The paper says they are willing to invest in areas that Warren Buffett himself wouldn’t.

They are each thought to manage a $9 billion portfolio and usually make the smaller investments, while Warren Buffett makes the big bets.

The Apple holding makes Berkshire Hathaway the 56th largest shareholder.

Apple is not Berkshire Hathaway’s only technology investment. It is also the biggest shareholder in IBM and increased its holding in the first quarter.

However, Warren Buffett admitted at Berkshire’s annual meeting last month that his investment firm had been slow to get involved the new tech industry. He has always said he would not invest in companies he doesn’t understand.

On May 16, Warren Buffett also told CNBC that he would consider helping Dan Gilbert, chairman of Quicken Loans, finance a bid for Yahoo.