An SEC filing showed that Warren Buffett's Berkshire Hathaway bought a stake in Barrick Gold in the second quarter.
Business Insider reports that Barrick Gold surged more than 10% in premarket trading Monday.
Berkshire Hathaway bought 21 million shares of the gold and copper miner.
The total stake in Barrick Gold was worth about $564 million, according to the Friday filing.
The buy comes as a bit of a surprise.