Co-head and managing director of BMO's metals and mining group Jason Neal will take over as CEO at TMAC from February 15.
Last year, the company celebrated its first gold pour at the Hope Bay project in Canada but also struggled with commissioning the plant there.
Neal led TMAC's 2015 IPO in his 21 years with BMO.
His current employer maintained TMAC's target price at C$9 (US$7.25) - lower than the current $10.54/share - following the announcement.
TMAC chairman Terry MacGibbon said the existing relationship was important in Neal getting the job.
"I have known and worked closely with Jason over the past 15 years and have great respect for his team building, management and analytical skills and am most excited about Jason bringing his energy, strategic thinking and discipline to TMAC as we continue to grow the company," he said.
"Jason will have overall responsibility for our strategic planning, vision, growth, leadership and ensuring that we effectively carry out strategic plans approved by the board."
TMAC struggled with consistency from its plant at Hope Bay in 2017, although managed to improve recoveries from an average of 64% in the September quarter to 72% in the December quarter.
