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 KapStone Paper and Packaging Corp. (NYSE: KS) traded as much as 11% lower today after the company released earnings.

So what: Sales increased 17% to $206.7 million, and net income jumped 137% to $15.1 million, or $0.32 per share, this quarter. That fell slightly short of the $207.9 million in sales and earnings per share of $0.35 that analysts had expected.

Now what: Shares have been trending lower all day after a spike this morning. But the earnings miss wasn't by a wide margin, and the company's growth, along with increased prices this quarter, should help future earnings. I think today's discount is a great buying opportunity, and the company's 11.6 estimated 2011 earnings multiple is very attractive given the company's growth.

Interested in more info on KapStone Paper? Add it to your watchlist.

Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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.