Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of rare earth oxide producer Molycorp (NYSE: MCP) climbed as much as 12% in early Tuesday trading after China announced plans to cut its rare earth exports by 11% next year.

So what: China accounts for more than 90% of the world's rare earth supplies -- vital for high-tech products like smartphones and hybrid vehicles -- so a cut in exports would naturally serve to increase demand for products from competing North American companies. It's no surprise Mr. Market is sending stocks like Rare Element Resources (AMEX: REE) and Market Vectors Rare Earth/Strategic Metals ETF (NYSE: REMX) much higher today, as well.

Now what: While the rare earth bull case sounds seductive, it's still one that most investors should simply ignore. It was only in October that China was looking to end its trade "embargo," so unless you're willing to be at the mercy of regulatory whims, on top of the extreme day-to-day swings of rare earth stocks, it's far safer to just stay on the sidelines. Molycorp, in particular, now sports a market cap of about $4.5 billion, which is tough to justify under any reasonable scenario.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.