The US and Canada haven’t exactly been on the best terms lately.

First, LA’s Kendrick Lamar and Toronto’s Drake engaged in a very public battle of words. Then, at the Winter Olympics, the US beat Canada in overtime in both the men’s and women’s hockey gold-medal games.

The Americans won all three of those contests. But Canada is coming back for a rematch — this time in the much more consequential arena of global trade. Consider the beef reheated.

The index-level market impact on the US was muted on Monday in the first full day after trade-war tensions reignited. But underneath the surface, it was clear which parts of the market have the most at stake if the US and Canada stay at odds for any length of time. Let’s break it down:

The winners: US steelmakers

The reasoning here is straightforward: With less competition north of the border, American steelmakers can grab more market share and juice profits. Top beneficiaries on Monday included Cleveland-Cliffs, Nucor, and Steel Dynamics, although — as the chart below shows — they gave up most of their gains by end of day.

The losers: Auto manufacturers

The US and Canada may be neighbors, but their auto supply chains operate like one factory.

The years spent building an integrated North American logistics network may now work against automakers. Tariffs threaten to throw off production schedules, squeeze margins, and — if no resolution comes — eventually raise prices for Americans.

US automakers hit included Ford (-3%), Stellantis, (-3%), and GM (-1%).

Watch the currency market

The Canadian dollar fell as much as 0.7% versus its US counterpart on Monday.

A weaker loonie is less a trade-war casualty than a real-time vote on which country has more to lose. For Americans, it may mean little beyond a cheaper ski trip. For Canada, it is a warning that investors see a bigger hit to economic growth materializing.

What’s next

For now, the market is treating the US-Canada flare-up as a sector-specific issue, not a systemic one.

But if retaliation continues, the fight could start to threaten North America’s long-standing trade infrastructure. The fallout would show up in corporate margins, investment plans, and price tags on both sides of the border.

At that point, this would be more than a cross-border skirmish — and much harder for the broader market to ignore.