Shares of BHP Group Ltd. /zigman2/quotes/208108397/composite BHP -0.35% /zigman2/quotes/201448516/delayed AU:BHP +0.47% took a 3.1% hit in morning trading Monday, after the Australia-based mining giant said it has initiated a review of its petroleum business, which could include a sale. The company confirmed, in "response to press speculation," that was in talks to sell the business to Woodside Petroleum Ltd. /zigman2/quotes/206334215/composite WOPEY -1.67% /zigman2/quotes/203437212/delayed AU:WPL -1.76% , followed by a distribution of Woodside shares to BHP shareholders. Woodside's U.S.-listed shares sank 5.2% in Monday morning trading. "While discussions between the parties are currently progressing, no agreement has been reached on any such transaction," BHP said in a statement. "A further announcement will be made as and when appropriate." BHP's stock has gained 15.4% year to date, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.40% has advanced 18.4%.