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 Packaging Corp of America (NYSE:PKG) dropped as much as 10% today after reporting earnings that fell well short of expectations.

So what: Revenue was down slightly in the first quarter to $1.43 billion and GAAP net income rose slightly to $90.8 million, or $0.92 per share. But on an adjusted basis earnings were $1.01 per share, which was below Wall Street's estimate of $1.08 and below the company's own guidance of $1.07-$1.10 per share in earnings.  

Now what: Management blamed poor weather for most of the weak performance and said conditions should improve later in the second quarter. For me, the problem is that at 18 times earnings the stock is very expensive for a company with no growth. For that reason, I'll sit out even today's discount because I think there are better values on the market and even better dividends than Packaging Corp's 2.8% yield today.