The Billings-based company operates the only platinum and palladium mines in the U.S., deep beneath southern Montana's rugged Beartooth Mountains.
Buoyed by high precious metals prices, Stillwater made two major purchases in recent years that executives said were designed to diversify its holdings. Those purchases were a palladium, copper and gold reserve in Canada, worth $118 million when it was announced, and a copper and gold reserve in the Andes of Argentina initially valued at $450 million.
The company has since revealed that the palladium content of the Canadian reserve was overestimated. And the copper deposit in Argentina could cost up to $2.5 billion to develop, a questionable prospect in a country with unsettled politics that have prompted other companies to stay out, Schweitzer said.
Stillwater last year sold a 25 percent stake in its Marathon project in Ontario to Mitsubishi Corp. for $81 million. Mining is expected to begin in 2017.
Without a change in course, the governor said, Stillwater potentially faces the same fate that befell Montana's legendary Anaconda Mining Co. That copper industry giant cratered after the Chilean government took over much of its foreign assets in the 1970s, leading to large-scale layoffs among Montana miners.
The former Montana governor owns 25,000 shares of Stillwater, worth roughly $325,000 at current prices, according to documents provided by the Clinton Group. He bought the stock after leaving office, between Jan. 23 and Feb. 20.
The Clinton Group holds almost 1.3 million shares, giving it a 1 percent stake in the company.
On Monday, Stillwater shares dropped 14 cents on the New York Stock Exchange to $12.85, a loss of about 1 percent.
The overwhelming majority of the platinum and palladium mined by the company is used by automotive companies in catalytic converters, which help control pollution.
Schweitzer said he wants the company to consider putting the foreign assets up for sale, particularly its property in Argentina. That comes after the Clinton Group in a December letter called for the retirement of Stillwater Chairman and Chief Executive Officer Frank McAllister.