How Do Alcoa and Century's Cost Curves Compare as US Smelter Capacity Ramps in 2026?

Data as of: FY 2025 (Jan–Dec)

Overview

Alcoa (AA) and Century Aluminum (CENX) are the two dominant US primary aluminum producers, but they operate at vastly different scales and cost structures. As both companies ramp domestic smelter capacity in 2026—Alcoa restarting idled potlines and Century building its new $4B+ greenfield smelter in Kentucky—understanding their relative cost positions is critical for investors evaluating the US aluminum supply renaissance.

Full-year 2025 results reveal a clear divergence: Alcoa's integrated bauxite-to-aluminum model delivered a 13.6% gross margin on $12.7B in revenue, while Century's pure-play smelting operation managed just 10.1% on $2.5B. The gap tells a story about vertical integration, energy contracts, and capital allocation heading into a pivotal year.

The Comparison

Revenue & Scale

Alcoa's scale advantage is commanding—5x Century's revenue—but Century is growing faster at nearly 14% YoY versus Alcoa's 4.5%. Century's growth reflects higher realized aluminum prices flowing through a smaller revenue base, plus incremental volume from its Hawesville, Kentucky smelter.

Profitability & Cost Structure

Alcoa's cost advantage is structural. As a vertically integrated producer owning bauxite mines and alumina refineries, Alcoa controls its input costs from the ground up. Its 13.6% gross margin reflects this integration—when alumina prices spike (as they did in 2024–25), Alcoa captures the margin internally rather than paying it to a third-party supplier.

Century, by contrast, is a pure-play smelter that purchases alumina on the open market. This exposes it directly to alumina price volatility. Its 10.4% gross margin is thinner and more vulnerable to input cost swings. The EBITDA margin gap is even starker—14.6% vs 6.0%—suggesting Century carries higher fixed overhead relative to its output.

Balance Sheet & Financial Health

Alcoa executed a remarkable deleveraging in 2025, reducing total debt from $2.8B to virtually zero while generating $567M in free cash flow. This fortress balance sheet gives Alcoa significant flexibility to fund capacity restarts without dilution or leverage.

Century carries $548M in debt against $136M in cash, resulting in 2.7x net leverage. While manageable, Century's planned Kentucky greenfield smelter will require billions in additional capital. The company has secured Department of Energy loan commitments, but execution risk remains elevated. Century's higher current ratio (1.97 vs 1.45) reflects working capital management, but the leverage picture clearly favors Alcoa.

Valuation

Century trades at an extreme premium on trailing metrics (138x P/E, 41x EV/EBITDA) reflecting a depressed 2025 earnings base. The forward P/E of 7.4x suggests the market expects a dramatic earnings inflection—likely tied to the Kentucky smelter coming online and higher aluminum prices. Alcoa is more reasonably valued at 13x forward P/E and 8.6x trailing EV/EBITDA, reflecting its mature, integrated earnings profile.

Key Takeaways

1. Alcoa owns the cost curve advantage today. Vertical integration into bauxite and alumina gives AA a 320bp gross margin edge and 860bp EBITDA margin advantage over Century. This structural moat widens when alumina prices are elevated.

2. Century is the higher-beta capacity growth story. CENX's planned Kentucky smelter represents a transformational capacity addition for a $2.5B-revenue company. If executed well, it could shift Century's cost curve materially—but that's a 2027–28 story, not a 2026 reality.

3. Balance sheet quality isn't close. Alcoa enters 2026 essentially debt-free with $1.6B in cash. Century carries $548M in debt and needs massive external financing for its greenfield build. In a commodity downturn, Alcoa survives; Century would face real stress.

Investment Implications

Who to Own

Alcoa (AA) for risk-adjusted exposure to US aluminum capacity growth. The debt-free balance sheet, 14.6% EBITDA margins, and integrated cost structure provide downside protection while still capturing aluminum price upside. At 13x forward earnings, the valuation is reasonable for a commodity producer entering a favorable supply cycle.

Who to Watch

Century (CENX) offers higher upside if the Kentucky smelter executes on time and within budget—the forward P/E of 7.4x implies massive earnings growth expectations. But the 2.7x leverage, thin margins, and capital-intensive build program make this a higher-risk bet. Wait for concrete construction milestones before building a position.

What to Watch

• Q1 2026 alumina pricing: Alcoa's margin advantage widens or narrows based on alumina spot prices, which directly impact Century's COGS
• Kentucky smelter construction updates: Any delays or cost overruns would pressure CENX's valuation thesis
• Section 232 tariff developments: Both companies benefit from US aluminum tariffs, but Century's domestic-only production base makes it the purer tariff beneficiary
• LME aluminum price trajectory: At $2,500+/ton, both companies are profitable; below $2,200, Century's margins compress to breakeven

Sources: Alcoa Corporation FY 2025 financial statements, Century Aluminum Company FY 2025 financial statements, company snapshots as of March 2026.