Boliden AB (STO: BOL) warns Garpenberg seismic damage will cut 2026 output and hit Q1 EBITDA

Boliden AB (STO: BOL) said on March 25 that abnormal seismic activity at its Garpenberg mine in Sweden has eased enough for low-level mining to resume in the second quarter, but the company now expects the most affected part of the mine to remain offline through 2026. The immediate consequence is a sharp reduction in near-term output, with Garpenberg now estimated to run at around 30% of its guided annual capacity of 3.7 million tonnes until further notice. Boliden AB also said first-quarter EBITDA will take an approximately SEK 400 million hit at current prices and terms. For investors, this is not just an operational interruption but a reminder that one of Boliden AB’s most profitable mines has abruptly become a constraint on earnings visibility.

What does Boliden AB’s Garpenberg update really say about the scale of operational damage?

The company’s update was more sobering than the headline suggestion that mining will restart in the second quarter. Inspections have shown that major infrastructure such as crushers, the hoist system, and workshops is largely intact, which is the good news and probably the only reason the restart conversation exists at all. The bad news is that a meaningful amount of operating media and support systems, including ventilation, compressed air, water management, electrical systems, and backfill paste, suffered damage and still require renovation. More importantly, Boliden AB said major damage has been observed in the upper parts of Lappberget, the dominant ore body at Garpenberg, and that mining in those areas is not expected to be possible in 2026.

That matters because Garpenberg is not a peripheral asset. Boliden’s own operational materials show that about 3.6 million tonnes were processed there in 2025, and more than 75% of mined tonnage came from Lappberget. A recent company resource summary also said silver accounted for 47% of Garpenberg’s revenue in 2025, while zinc accounted for 32%. In plain English, this is not a case of a diversified mine losing a side pocket of output. It is a case of a flagship underground operation losing access to the most important part of its most important ore body. Mines do not shrug that off with a polite spreadsheet adjustment.

Why is the Garpenberg mine disruption more important than a single SEK 400 million EBITDA hit?

The SEK 400 million first-quarter EBITDA impact is the obvious headline number, but it likely understates the broader significance. Garpenberg has been described in Boliden-related coverage as the company’s most profitable mine, and Boliden itself only a week earlier used its Capital Markets Update to justify a SEK 4 billion investment in a new hoist system there, framing Garpenberg as a long-duration earnings asset. When a company commits fresh capital to expand or strengthen an asset and then, days later, warns that the most affected part of that same mine may not operate again this year, the issue moves from quarterly noise to portfolio risk.

There is also a quality issue inside the volume issue. Boliden AB said average zinc grade is now expected to deteriorate slightly compared with previously communicated levels, while silver grade should improve. That mix shift may soften some revenue pain because silver has become increasingly important to Garpenberg’s economics, but it does not neutralize the problem. Lower throughput at roughly 100,000 tonnes per month initially, versus a pre-event guided annual capacity of 3.7 million tonnes, still implies a mine operating far below normal utilization. In underground mining, underutilization has a nasty habit of making every tonne more expensive.

How exposed is Boliden AB to Garpenberg as a profit engine inside its wider mining portfolio?

Boliden AB is not a single-asset miner, but Garpenberg has been one of its standout underground assets because of its scale, metal mix, and profitability. The company’s March 18 Capital Markets Update explicitly called Garpenberg a highly profitable mine. That framing now becomes important because investors have to think about replacement earnings. If Garpenberg contributes less volume and its core Lappberget sections remain unavailable, the burden shifts to other mines and to smelter performance to absorb the shortfall. That is possible, but not frictionless.

There is another strategic wrinkle. Boliden AB has been leaning into future-facing investment projects, including the Odda zinc smelter expansion and infrastructure upgrades across its system. Garpenberg feeds into the group’s broader metals value chain. A mine disruption therefore does not stay neatly underground. It can ripple through feed planning, smelter optimization, and capital allocation priorities, especially when the affected mine sits in a region where Boliden has both operational depth and reputational visibility.

What does Boliden AB’s recent stock performance suggest about investor sentiment now?

Boliden AB shares closed at SEK 586.80 on March 25, up from SEK 571.60 on March 24, according to historical pricing data. Over the last five trading sessions shown in the available data, the stock rose from SEK 540.00 on March 20 to SEK 586.80 on March 25, an increase of about 8.7%. But that short bounce sits inside a much weaker one-month picture: the shares were at SEK 722.60 on February 25, which means the stock is down about 18.8% over that period. The 52-week range available from multiple market data sources is SEK 259.40 to SEK 727.80, leaving the current price well below the high even after the recent rebound.

That price action suggests investors may be balancing two competing views. On one hand, the market appears relieved that Garpenberg was not structurally crippled from top to bottom and that limited production can resume in the second quarter. On the other hand, the stock’s sharp retreat from late-February levels suggests confidence had already been dented, and the new update does not fully restore the prior thesis. Current consensus data visible through market platforms points to a broadly neutral analyst stance, with a mix of buy and sell recommendations and an average price target only modestly above recent trading levels. That is not panic, but it is hardly a standing ovation either.

What happens next for Garpenberg, zinc-silver output, and Boliden AB’s 2026 narrative?

The next key issue is ramp speed. Boliden AB said production is expected to restart in the second quarter at roughly 100,000 tonnes per month, which is around 30% of previous levels, and that an increase in the second half of 2026 may occur. That wording is cautious for a reason. Underground mines affected by seismic events do not return on management optimism alone. They return on rehabilitation progress, geotechnical confidence, and the ability to safely restore ventilation, water systems, paste backfill, and electrical infrastructure while protecting crews.

For the broader metals market, the event is a reminder that operational risk in deep underground mining remains stubbornly physical, no matter how polished investor decks become. Garpenberg is important not just because it produces zinc and silver, but because Europe needs reliable domestic and regional metal supply as industrial policy, defense manufacturing, electrification, and resource security all climb the agenda. A constrained Garpenberg does not rewrite global zinc supply on its own, but it does reduce flexibility in a system where dependable European production is strategically useful.

For Boliden AB, the April 28 first-quarter report now matters more than usual. Investors will want more than the EBITDA hit. They will want evidence that rehabilitation timelines are holding, that unaffected ore bodies can support a credible partial recovery, and that management can still defend its capital allocation logic around Garpenberg after the disruption. If the second-quarter restart stabilizes and second-half ramp-up materializes, the episode may eventually be remembered as a painful but contained setback. If not, 2026 could become a year in which one of Boliden AB’s best assets spent too long proving it was still dependable.

What are the key takeaways from Boliden AB’s Garpenberg seismic disruption for investors and the mining industry?

• Garpenberg is resuming, but at a level that still implies severe operational constraint rather than a normal restart.
• The upper parts of Lappberget, the dominant ore body, are not expected to be mined in 2026, which makes this a core-asset issue.
• The SEK 400 million Q1 EBITDA hit is the first visible cost, not necessarily the full economic consequence.
• Lower zinc grades and improved silver grades may change revenue mix, but they do not offset the damage from sharply lower throughput.
• Garpenberg’s status as a highly profitable mine means disruption there has an outsized effect on confidence in Boliden AB’s earnings base.
• The event tests whether Boliden AB’s wider mining and smelting portfolio can absorb a shortfall from one of its most valuable assets.
• Recent share-price recovery looks more like relief that the mine is not fully lost than proof that investor concern has disappeared.
• The March 18 decision to keep investing heavily in Garpenberg shows management still sees long-term value, but execution risk has just become much more visible.
• For European metals supply, the disruption highlights how vulnerable even established underground mines remain to geotechnical shocks.
• Boliden AB’s April 28 Q1 report is now the next major checkpoint for judging whether this is a contained disruption or a deeper 2026 earnings problem.