(Bloomberg) -- A wider strike by the United Auto Workers would have an impact beyond the three Detroit carmakers, with struggling steelmakers a particularly vulnerable target.

The union is scheduled on Friday to discuss adding plants to its strike against General Motors Co., Ford Motor Co. and Stellantis NV, which produces vehicles under numerous brands including Chrysler and Jeep. A UAW negotiator said the latest offer from Stellantis “didn’t look good for us.”

The strikes are already expected to knock out 1.1 kilotons of copper demand and 9.5 kilotons of aluminum demand each week they go on. But steelmakers are in the crosshairs, with US Steel Corp. already idling a blast furnace in Illinois in response to the walkout.

The historical analogies aren’t kind. The last time US auto workers struck, against GM in 2019, steel prices dropped 17%. In addition, shares of Timkensteel Corp. sank 21% during the strike, Suncoke Energy fell 17% and Cleveland-Cliffs Inc. dropped 15%.

“If strikes target production of high-profit-margin models like full-size SUVs and trucks, which have higher metals intensity,” the impact on metal demand could be larger than 2019 strike against General Motors, according to JPMorgan analyst Gregory Shearer.

What’s at Stake as US Autoworkers’ Strike Drags On: QuickTake

Now, the UAW has called its first-ever strike at all three of the Detroit-based car manufacturers, impacting production simultaneously. 

“Auto is one of the most concentrated sources of US steel demand (about 25%), and we expect further capacity could be idled or reduced should the strike prolong,” JPMorgan analyst Bill Peterson wrote in a note to clients on Thursday. 

So far, members of the S&P Supercomposite Steel Index — which includes major producers Nucor Corp., Reliance Steel & Aluminum Co., Steel Dynamics Inc. and Cleveland-Cliffs Inc. — have already lost a combined $3.9 billion in valuation.

That said, unless there’s a protracted impasse between the auto companies and their union, analysts expect steel prices to start recovering once the parties appear close to an agreement.

“We see potential for a sharp rebound in pricing following a resolution given extended maintenance and lean inventories among both steel buyers and automakers,” Peterson wrote.

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