Gold prices are at record highs. But disappointing results at the world’s largest miner of the yellow metal signals companies may be struggling to capitalize on sizzling demand.

Newmont shares plunged the most in more than 25 years, tumbling 15% after the Denver-based company posted earnings, revenue and profit margins that fell short of analysts’ estimates in the third quarter, dragged down by higher costs for labor, diesel and other operating expenses. Top rivals Barrick Gold and Agnico Eagle Mines also saw their shares drop.

Analysts had high hopes for the industry, with gold among the best-performing commodities this year, surging more than 30% on the outlook for lower interest rates and geopolitical turmoil. But Newmont’s results revealed that big gold producers are still wrestling with inflationary pressures, especially regarding labor costs, that have lasted longer than expected.

“There’s a potential read-through here, assuming Newmont’s takeaways are accurate, that this is a risk factor for the industry,” said Josh Wolfson, a mining analyst with Royal Bank of Canada.

Newmont earned 80 cents a share, well short of the average estimate of 89 cents among analysts surveyed by Bloomberg. Revenue of $4.61-billion also trailed estimates, as did its gross profit margin, which slipped below 50%.

The company said it spent more to dig up the precious metal at its mines in Australia, Canada, Peru and Papua New Guinea than in the previous quarter. Capital expenses rose 10% due to expansion projects in Australia and Argentina, while some of the company’s highest expenses came from major assets it picked up through last year’s $15-billion takeover of Newcrest Mining.

Some of those cost issues are specific to the company, and not necessarily indicative of a broader industry trend. Newmont is undertaking costly maintenance work at its Lihir mine in Papua New Guinea — a notoriously complex operation in a remote region — and it spent more to re-start its Cerro Negro mine in Argentina after operations were paused due to the deaths of two workers in April.

But the company’s growing costs for workers could signal trouble across the industry.

“It’s the labor costs where we’re seeing that escalation,” CEO Tom Palmer told analysts in a conference call Thursday.

“Whether that be maintenance shutdowns, maintenance that you use to supplement your workforce, costs of running camps, costs of flying people to and from the camps — that’s where we’re seeing some escalation beyond what we’d assumed at the start of the year.”

Shares of mining companies have historically been seen as offering better returns than owning the metal, partly due to greater investment options and shareholder payouts, but that relationship broke down over the past 15 years as major expansions left producers with big debts and angry shareholders.

Newmont’s earnings also serve as a preview for Canada’s Barrick, which shares a giant mining complex with Newmont in Nevada. The Nevada mines produced less gold compared to the previous quarter.

Despite investor disappointment, the gold miners are still being helped by the bullion boom: Newmont posted its highest quarterly profit in five years, raking in $922 million. Analysts expect Newmont is on track to net $3.2 billion in profit this year — which would be a record for the company.

Even after today’s plunge, Newmont’s shares are up 19% this year.

Barrick, Agnico and other big producers including AngloGold Ashanti and Gold Fields are also expected to rake in windfall returns by the end of the year.

“The street expectations were too high,” said Carey MacRury, a mining analyst at Canaccord Genuity who recommends investors buy the shares. “It was negative, no doubt, but I don’t think it’s as negative as what the market’s telling us today.”