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 precious-metal miner Endeavour Silver (NYSE: EXK) weren't looking too shiny today, as they slumped as much as 12% in intraday trading.

So what: This morning, Endeavour announced earnings for its first quarter, and the numbers looked pretty darn good. Revenues jumped by 94% year over year to $35 million, while adjusted earnings rocketed from $1.1 million last year to $14.5 million. On a per-share basis, the company registered a $0.18 profit, which was easily better than the $0.12 that Wall Street was expecting.

Now what: With results like that, why in the world would shares be down today? A key driver for the company's profit gains was the 96% increase in the realized silver price versus last year. Over the past week, though, silver has taken a beating, as evidenced by the explosion of volume for the iShares Silver Trust (NYSE: SLV) and its 26% drop since last Thursday. When your revenue relies heavily on the price of silver -- as is the case for Endeavour -- this is not an encouraging development.

Want to keep up to date on these stocks?

Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

Fool contributor Matt Koppenheffer has no 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 on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.