What Does Mt. Holly's 100% Restart Mean for US Domestic Aluminum Self-Sufficiency?

Event Date: H1 2026 (Full capacity expected by summer 2026)

What's Happening

Century Aluminum (CENX) is restarting its Mt. Holly smelter in South Carolina to 100% capacity — a $50 million investment that will push the facility's annual output above 220,000 metric tonnes. Management confirmed on the Q4 FY2025 earnings call (February 20, 2026) that incremental production began in Q2 2026, with full capacity expected by summer. The restart will increase Century's total US aluminum production by approximately 10%.

This is the most significant expansion of domestic primary aluminum capacity in years, arriving at a moment when US self-sufficiency in aluminum has become a strategic priority reinforced by Section 232 tariffs and rising geopolitical tension around supply chains.

The Outcome So Far

ON TRACK: Mt. Holly ramp proceeding toward full 100% restart by mid-2026

The restart has not been without bumps. Mt. Holly experienced brief operational instability in Q4 FY2024 and Q3 FY2025, temporarily reducing shipments. But management noted on the Q3 call that the issues were resolved, and the facility returned to expected strong performance by Q4 FY2025.

Why This Matters for US Aluminum Self-Sufficiency

The United States currently imports roughly 75–80% of its primary aluminum needs. Domestic smelting capacity has contracted sharply over the past two decades — from over 20 active smelters in the early 2000s to fewer than six today. Century Aluminum is one of only two publicly traded US primary aluminum producers, alongside Alcoa (AA), which operates a far larger global footprint ($17.5 billion market cap vs. CENX's $5.7 billion).

Mt. Holly's restart is significant for several reasons:

1. Immediate capacity addition: An incremental ~75,000+ tonnes of annual US output (the difference between curtailed and full capacity) narrows the import gap.
2. Low-carbon advantage: Century produces aluminum with carbon emissions 75% below the industry average, leveraging renewable energy. Mt. Holly's power agreement extension through 2031 secures this advantage.
3. Section 232 economics: Tariffs on imported aluminum have driven the US Midwest Premium higher — management noted premiums reached $602/tonne in Q1 FY2025 and continued climbing. This makes domestic production increasingly economic.
4. Broader pipeline: Century is also advancing a new greenfield US smelter project in partnership with EGA, which management says could triple US production capacity by the end of the decade.

Financial Context

Century's FY2025 results show a company scaling into the aluminum upcycle:

FY2024 net income and EBITDA include a ~$247M benefit in Q1 (likely tax credit recognition). Adjusted EBITDA run-rate improved significantly through H2 FY2025.

*The reported $142M EBITDA for FY2025 reflects GAAP figures; management-reported adjusted EBITDA was substantially higher after excluding one-time items like the Grundartangi transformer outage and Hurricane Melissa impacts at Jamalco.

Critically, management guided Q1 FY2026 adjusted EBITDA of $215–235 million — a massive step-up that reflects the combined benefit of higher aluminum prices, rising premiums, Grundartangi's return to full production by end of July 2026, and initial Mt. Holly restart volumes.

FY2026 shipment guidance of approximately 630,000 tonnes represents the full benefit of Mt. Holly at capacity.

Competitive Landscape

For comparison, Alcoa (AA) generated $12.7 billion in FY2025 revenue and $1.15 billion in net income, operating a globally diversified bauxite-alumina-aluminum chain. Aluminum Corporation of China (ACH), the world's largest aluminum producer, reported $2.76 billion in revenue for FY2025 but posted a net loss of $1.1 billion amid restructuring.

Century's differentiation lies in its pure-play US smelting exposure and low-carbon positioning — attributes that command premium valuations as supply-chain security becomes policy priority.

Investment Implications

Bull Case

• Mt. Holly restart adds ~$30M+ in incremental annual EBITDA at current aluminum/premium prices
• FY2026 EBITDA guidance implies a dramatic re-rating: at $215–235M quarterly, annualized EBITDA of ~$850–940M would compress the current 41x EV/EBITDA multiple to under 8x
• The new US smelter project with EGA represents a generational capacity expansion option
• Section 232 tariffs and Buy America provisions create a durable demand premium for domestic metal

Bear Case

• CENX trades at 138x trailing P/E — the re-rating depends entirely on forward execution
• Debt/equity of 0.66 with $548M in total debt leaves limited margin for operational setbacks
• Grundartangi (Iceland) had transformer failures in Q3 FY2025; similar unplanned outages could derail the ramp
• Aluminum price cyclicality: an LME downturn would compress margins regardless of volume gains

What's Next

1. Q1 FY2026 Results (May 2026): First quarter with Mt. Holly restart volumes. Watch for confirmation of $215–235M adjusted EBITDA guidance.
2. Summer 2026: Full 100% capacity milestone at Mt. Holly — the definitive event.
3. Grundartangi Recovery: Full production expected by end of July 2026; watch for any delays.
4. New US Smelter: Progress on the Oklahoma greenfield project with EGA; any JV partner announcement would be a major catalyst.
5. Hawesville Site: Strategic review ongoing with increased third-party interest — potential redevelopment or sale.

Sources: Century Aluminum Q1–Q4 FY2025 earnings calls, CENX and AA financial statements (FMP), company snapshot data.