Metals and materials stocks initially rallied after the United States imposed 50% tariffs on about $20 billion of Canadian imports under Section 338 of the Tariff Act of 1930, prompting Canada to announce retaliatory measures worth $20 billion. The Canadian duties cover more than 700 U.S. goods, range from 15% to 50% and are scheduled to take effect on Sept. 8. Nucor, Steel Dynamics, Cleveland-Cliffs and Century Aluminum gained, the VanEck Steel ETF (SLX) rose 1.6% and the State Street Materials Select Sector SPDR (XLB) reached an intraday all-time high, but the rally faded as XLB ended the week lower and SLX nearly flat. Analysts said U.S. steelmakers could benefit from a larger protected market, while higher metal costs and repeated border crossings could pressure manufacturers, automakers and construction companies. Public opinion also diverged: 58.7% of Americans disapproved of President Donald Trump's trade approach versus 34.5% who approved, while 76% of Canadians supported ending trade talks and 62% backed the counter-tariffs. The legal basis for the measures remains untested, with no lawsuit filed and experts divided over whether Section 338 was superseded by later trade laws or required evidence of measurable harm. The dispute is also clouding the USMCA, delaying investment and complicating integrated North American supply chains, while a possible additional 7.5% tariff on China could deepen uncertainty.