MP Materials (MP -10.99%) stock tumbled 9% through 3 p.m. ET Friday after London’s Financial Times reported on a potential competitive threat to MP’s vast investments (already made) in reviving the American rare earth mining industry, and capacity to produce rare earth magnets domestically.

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Could Niron replace MP?

Automotive giants Stellantis and General Motors, along with Volvo and Samsung, are investing $150 million in a start-up called Niron Magnetics, which aims to make magnets from common elements such as iron and nitrogen — rather than rare earth elements (which aren’t exactly rare, but can be hard to refine). Various U.S. government agencies have granted the company nearly $70 million more in tax credits and other subsidies.

Niron is building an iron nitride magnetics factory in Minnesota, capable of producing 1,500 tons of magnets annually, and says its magnets will be 18% more powerful than certain — much more expensive — rare earth magnets.

Is MP Materials stock a sell?

I wouldn’t panic just yet, however. While Niron’s magnets have been reported to be better than some of the best rare earth magnets, this appears based on lab reports at present, and the company hasn’t yet proven it can produce magnets of the reported superiority, at scale, and at affordable prices.

It’s also worth noting that while Niron has attracted substantial support from government and industry, so too has MP Materials — up to and including the U.S. government taking an equity stake in the company. And MP Materials has a huge lead in building out mining and manufacturing operations to support production of its own magnets.

True, if all of Niron’s claims prove out, there could be risk to MP here. But it’s a big “if,” and too soon to tell just how big of a risk.