(Reuters) -Newmont ( NEM ) said on Monday Tom Palmer will retire by the end of the year, in an unexpected move after spending more than a decade with the world's largest gold miner.

Rival Barrick Mining also announced the sudden resignation of Mark Bristow as CEO earlier in the day. Bristow had led the Canadian miner for nearly seven years after its merger with Randgold Resources.

Both Newmont ( NEM ) and Barrick face a period of significant industry transformation amid these leadership shifts.

Palmer will step down on December 31 and serve as a strategic adviser until his retirement in March next year.

He had joined Newmont ( NEM ) in 2014 and became the chief operating officer in 2016 before being appointed as CEO in 2019.

During his tenure, Newmont ( NEM ) completed transformative deals, including the Goldcorp acquisition, the Nevada Gold Mines joint venture, and the $17 billion acquisition of Australian mining company Newcrest to create a top-tier global portfolio.

Earlier this year, Karyn Ovelmen also announced her decision to step down as the chief financial officer of Newmont ( NEM ), after just over two years at the company. Insider Peter Wexler was named as interim CFO.

Palmer will be succeeded by insider Natascha Viljoen, effective January 1, 2026.

Viljoen, who joined the gold miner as chief operating officer in 2023, brings more than 30 years of global mining experience, including senior roles at Anglo American, BHP, and Lonmin, and as CEO of Anglo American Platinum.

At Newmont ( NEM ), she has focused on operations, portfolio integration, and talent development, emphasizing safety, operational excellence and sustainability.