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 mortgage insurer Radian Group (NYSE: RDN) jumped more than 10% in intraday trading on big volume.

So What: The entire mortgage insurance sector was up significantly today because investors saw hope that the companies would be able to put some of their losses back on the big banks. Now that Bank of America (NYSE: BAC) has halted foreclosures all over the country, the robo-signing issue is starting to reach a fever pitch. In the midst of all of this, investors in the mortgage insurance space are getting confident that the companies will be able to make some recoveries from lenders because of the lenders' sloppy practices.

Now What: This is certainly an interesting angle for the mortgage insurers, so it's no surprise that Radian, along with MGIC (NYSE: MTG), PMI Group (NYSE: PMI), Ambac (NYSE: ABK) and others are up notably while Bank of America, JPMorgan Chase (NYSE: JPM), and Wells Fargo (NYSE: WFC) slip. But it's hardly an open-and-shut case for the industry, so it's tough not to keep considering the shares of mortgage insurers to be very speculative.

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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 Motley Fool 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.