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 private mortgage insurer Radian Group (NYSE: RDN) shed more than 10% in intraday trading, as investors reacted to earnings from competitor PMI Group (NYSE: PMI).

So What: PMI Group's earnings clearly disappointed investors, sending its shares tumbling nearly 20%. Radian Group is set to report its earnings early next week, and investors may be taking PMI's lackluster report as a sign that Radian's results may disappoint as well.

Now What: Fellow private mortgage insurer MGIC Investment (NYSE: MTG) also fell on the news, which was a bit strange, considering that MGIC already reported earnings that came in above expectations. These mortgage insurers are all in pretty bad shape, but those investors still sniffing around Radian might be well advised to wait to freak out until it actually reports its own earnings.

Interested in more info on Radian Group? Add it to your watchlist.

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. 

Fool contributor Matt Koppenheffer does not own shares of 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 assures you no Wookiees were harmed in the making of this article.