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 platinum and palladium producer Stillwater Mining (NYSE: SWC) were getting hammered flat by investors today, losing as much as 20% in intraday trading on heavy volume.

So what: Stillwater announced today that it's paying roughly $450 million to buy Canadian miner Peregrine Metals. Peregrine owns Altar, which is a significant copper and gold project in Argentina. So why are investors freaking out about this? Probably because Stillwater is paying a massive premium for a company that doesn't have any revenue. While there is supposed to be a significant amount of copper and gold at Alta, it's still an undeveloped project and will require further investment by Stillwater in the years ahead.

Now what: The acquisition overshadowed some good news also announced by Stillwater today. For the second quarter, production of palladium and platinum topped the company's previous targets. Management expects that when the books are closed, the company will report $223 million in revenue for the quarter -- well above the $202 million that Wall Street was expecting. So while it would appear that Stillwater is delivering on its primary front, investors will need to be convinced that management is being smart and the Peregrine buy will pay off.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.