Canada’s Barrick Gold Corp. (ABX) has agreed to acquire its London-listed rival Randgold Resources Ltd. (GOLD) in a share-for-share merger.

In a statement, Barrick said the two companies will combine to create the world’s leading producer of gold. The combined firm will have a market value of $18.3 billion. Under the terms of the deal, Randgold shareholders will receive 6.1280 new Barrick shares in return for each Randgold share. Barrick shareholders will own about 66.6 percent of the newly formed company, leaving Randgold shareholders with about 33.4 percent ownership. (See also: How to Invest in Gold: An Investors Guide)

If all goes to plan and the merger wins approval from both regulators and shareholders, the New Barrick Group is expected to start trading on the New York Stock Exchange and the Toronto Stock Exchange in the first quarter of 2019. Randgold’s long-term chief executive Mark Bristow will serve as CEO of the new company, while Barrick’s John Thornton will become the executive chairman.

Shares in both companies rose slightly in pre-market trading.

“The combination of Barrick and Randgold will create a new champion for value creation in the gold mining industry, bringing together the world’s largest collection of Tier One Gold Assets, with a proven management team that has consistently delivered among the best shareholder returns in the gold sector over the past decade,” said Thornton, Barrick’s executive chairman.

The merger comes at a difficult time for the two companies. Both have lost about a third of their market capitalizations over the past year as Barrick was criticized for its strategy and Randgold was impacted by several operational issues, including a strike at one of its biggest mines.

Bristow, the new CEO of the combined Barrick and Randgold, sought to reassure investors that the merger will turn both companies into a more efficient and profitable entity. 

“Our industry has been criticized for its short-term focus, undisciplined growth and poor returns on invested capital,” he said. “The merged company will be very different. Its goal will be to deliver sector leading returns, and in order to achieve this, we will need to take a very critical view of our asset base and how we run our business, and be prepared to make tough decisions.” (See also: 8 Reasons To Own Gold.)