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 health insurer MedcoHealth Solutions (NYSE: MHS) got a nasty cold today and fell 11%.

So what: MedcoHealth lost a big pharmacy benefit contract with Blue Cross Blue Shield Association to CVS Caremark (NYSE: CVS). The $3 billion contract begins next year and won't impact MedcoHealth's earnings during 2011.

Now what: This is obviously a big blow for MedcoHealth, but the news hasn't been the boost you might expect for CVS Caremark. CVS' stock is only up 2% on the big win, so it appears investors are focusing on the negative news for MedcoHealth today. I wouldn't jump into MedcoHealth on this dip, but I will take a second look at CVS because the stock was only trading at a 12.4 forward multiple before this big contract is factored into expectations.

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