Officials plan to maintain a 50% duty on products in harmonized tariff schedule Chapters 72 and 73, apply a 25% tariff on other steel and aluminum-containing goods, and exempt imports with less than 15% metal content. Duties will be calculated on the full value of the imported items rather than just metal content.

Alcoa shares fell 1.6% in US postmarket trading as investors assessed the complexity and cost implications of the revised tariff structure on raw material imports. Companies had previously flagged challenges in assigning duties for products with minimal metal components, citing threats to sales and profitability.

By switching to a value-based tariff and introducing tiered rates, the administration aims to simplify duty calculations and potentially curb imports. This could support domestic aluminum producers like Alcoa by reducing competition, although downstream manufacturers may face higher input costs.