What happened

Shares of Canadian miner Northern Dynasty Minerals (NAK -1.97%) have been on a roller-coaster ride since May. The owner of the Pebble Mine project in Alaska saw it shares fall more than 30% today, bringing shares back to the levels of early May, after having soared almost 300% through late July.

Why the sudden plunge? Look to the Trump administration's opposition to the Pebble Mine project. 

heavy equipment shoveling from an open pit mine

Image source: Getty Images.

So what

Shares jumped as the mine owner struck an optimistic tone on July 24, when the U.S. Army Corps of Engineers, after two years, released the final version of an environmental impact statement on the copper, gold, and molybdenum project. Ron Thiessen, president and CEO, said at the time, "We're ecstatic to reach this major milestone in the advancement of the Pebble Project." Thiessen said it gave the company the potential to be one of the most significant American metals producers. 

But Bloomberg reported this past weekend that the Trump administration may be seeking to block the project.

Now what

The proposed mine, which is known to have deposits of copper, gold, and other minerals, is in a sensitive location, as it drains into Bristol Bay, which houses a productive wild salmon fishery. The president's son, Donald Trump Jr., wrote on Twitter, "The headwaters of Bristol Bay and the surrounding fishery are too unique and fragile to take any chances with," signaling his opposition to the project. 

Northern Dynasty responded to the reports of Trump opposition, saying that the project "can be done without harm to the Bristol Bay fishery." Investors are now reacting to the uncertainty. But that shouldn't be too much of a surprise, when major decisions on the business are out of the company's control.