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 minerals company Compass Minerals International (NYSE:CMP) fell 18% today after the company reported earnings.

So what: Second-quarter revenue fell 3% to $173.8 million because of a drop in specialty fertilizer sales due to a constrained supply of sulfate of potash. Earnings increased 12% to $10.6 million, or $0.32 per share, which became $0.31 after excluding one-time items. That fell well below estimates of $0.40 per share in earnings from Wall Street.  

Now what: Falling revenue wasn't a good sign today, and analysts at BMO Capital piled on by saying that they expect Russian potash producer Uralkali to increase supply, putting pressure on prices. The stock isn't a great deal anyway at 25 times earnings, too expensive for a stock that isn't growing. I'd stay away from the discount today and look for better deals in the mineral space.

Interested in more info on Compass Minerals? Add it to your watchlist by clicking here.

Fool contributor Travis Hoium has no position in any stocks mentioned. The Motley Fool owns shares of Compass Minerals. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.