What Kaiser Aluminum Corporation told the SEC could break it.

Kaiser Aluminum's fabricated-products revenue is concentrated in a small group of customers: one customer represented approximately 16% of net sales in both 2025 and 2024 (18% in 2023) and a second represented ~15% (16% in 2023), and its five largest customers together accounted for approximately 56% of 2025 net sales. Customer concentration is also visible in receivables (one customer 21% and a second 15% of the A/R balance at December 31, 2025). About 70% of shipments go directly to manufacturers/tier-one suppliers (aerospace, automotive, packaging) and 30% to metal service centers. The customers are not individually named, so this is captured as a concentration risk rather than edges; a prolonged downturn at one or more would materially reduce revenue. A high customer concentration.

“For the years ended December 31, 2025 and December 31, 2024, our largest customer accounted for 16% of Net sales.”

Kaiser acquired the Warrick (Newburgh, Indiana) rolling mill from Alcoa but remains dependent on Alcoa Corporation, which retains the adjacent site, for certain resources essential to Warrick's day-to-day operation — including potable water. It warns that if Alcoa failed to provide these resources, Kaiser could incur substantial costs to keep the Warrick rolling mill operational or face the temporary or permanent shutdown of Warrick's operations. Warrick is a major packaging (can-stock) facility, so this is a concentrated single-supplier, single-site dependence with a severe failure mode. A genuine sole-source/utility dependence (the Alcoa relationship is also captured as a supply edge).

“If Alcoa were to fail to provide these resources, we could incur substantial costs to keep the Warrick rolling mill operational”

Kaiser's dominant raw-material cost is alloyed/primary aluminum (hedged cost of alloyed metal was ~$1.92 billion of 2025 COGS, up 22% year over year), sourced from major suppliers including from Canada. U.S. aluminum trade policy is therefore a two-sided exposure: tariffs introduced to protect U.S. manufacturers from foreign price competition may not be fully effective, could disrupt supply chains, or could otherwise increase Kaiser's costs (e.g., higher Midwest premium / imported-metal cost), even as they can support domestic pricing. A specific trade-policy exposure tied directly to the primary-aluminum input (lower severity given the offsetting protective effect for a domestic producer).

“tariffs introduced to protect manufacturers in the United States from foreign price competition may not be fully effective or could disrupt supply chains or otherwise increase our costs.”