Everyone watches hot-rolled coil prices to read Nucor. Wrong chart. The mechanism that actually moves NUE's margin lives inside a bureaucratic side door most investors have never heard of: the Section 232 steel "inclusions" process. Commerce killed the old exclusion-request system in February 2025 — no more downstream users petitioning to escape the tariff. What replaced it runs the opposite direction: three two-week windows a year (May, September, January) where anyone, including steelmakers themselves, can petition Commerce to add more derivative products — finished goods made from steel — onto the tariffed list. Nucor has been one of the most aggressive filers. The first cycle alone added 400-plus HTS codes. Every code that lands on that list means an importer's landed cost jumps 25%, and every domestic mill selling a substitutable product gets a price umbrella it didn't have to build a single new furnace to earn. That's the real driver behind NUE's Q1 2026 gross margin doubling to 16% while import share of the U.S. market fell from 22% to 15%: it's a docket outcome, not a demand cycle.