A mine mishap or surprise tax hike could force high-debt operators to raise equity, diluting shareholdings.
Even if bullion's recent rally persists - it is up 9 percent this year to $1,290 an ounce - leveraged miners may be tempted to issue shares to shore up balance sheets, said Chris Mancini at Gabelli Gold Fund.
With nearly $21 billion in net debt, the world's four biggest gold miners - Barrick Gold, Newmont Mining , AngloGold Ashanti and Goldcorp - have a median net debt to operating income ratio of 2.2, Thomson Reuters data shows. For the S&P500, the ratio, which measures a company's ability to pay off debt, is 1.65.
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Franco-Nevada provides alternative financing for the industry. David Harquail, Franco's chief executive, estimates $27 billion in high-yield debt will need refinancing in coming years, creating opportunities for companies like his.
"This is a fantastic time to be in the business," said Tony Jensen, CEO of rival Royal Gold.
Oil, currency, bullion fillip
Gold stocks are now on a tear, driven by higher bullion, cheaper oil and currency moves. The S&P/TSX Global Gold Index rose 30 percent this month.
Miners with operations in Canada, Australia, South Africa and Russia, where currencies are sharply weaker against the U.S. dollar, have benefited most. They get U.S. dollars for their gold, while their local costs have dropped in dollar terms.
Canada-based miner Detour Gold has soared 43 percent this month. In Australia, Northern Star is up 45 percent and South Africa's Sibanye Gold has jumped 42 percent.
A nearly 60 percent slide in oil prices since June has also reduced costs, especially at large, mechanized mines.
"If you're open pit, you're remote and you move a lot of dirt, you're going to get a lot of benefit," said Lawrence Grech, PhillipCapital head of research.
Oil can represent as much as one third of a mine's operating costs. But relief won't be immediate or uniform. Barrick, for example, hedged some 50 percent of its 2015 oil exposure at $91 a barrel, while crude has dropped below $50.
"Lump of coal"
As miners start reporting fourth-quarter results, Goldcorp's writedown won't be the last. Barrick, the world's biggest gold miner, already warned it will reduce its Zambian copper mine valuation.
"Investors are going to get another lump of coal this season from the golds," Beristain said. "This is the third year in a row of multibillion-dollar writedowns and we are still not done."
Miners who valued in-the-ground reserves and resources a year ago at prices above today's $1,290 an ounce will likely cut those values, weighing on earnings.
"The mines should be reporting pretty good numbers, but...headline earnings, I doubt very much are going to be positive, for a lot of companies," said Adrian Day Asset Management President Adrian Day.