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 Coeur Mining Inc. (NYSE:CDE) fell as much as 12% today after the silver and gold miner reported a fourth-quarter loss.

So what: Quarterly revenue fell 18% from a year ago to $140.6 million due to lower metal prices and a 24% drop in the ounces of gold sold. Net loss was a whopping $1.08 billion, or $10.53 per share, driven by a $1.02 billion noncash impairment charge to lower the carrying value of gold and silver assets.

Now what: As is the case with any metals miner, results are largely dependent on metals prices. In that respect, I don't see much good news for gold or silver prices, and analysts expect a loss of $1.10 per share next year.

A write-off that is larger than a company's market cap is never good, and that's exactly what happened to Coeur Mining today. That's just the biggest sign that this is a stock long-term investors would be wise to stay far away from.