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 dermatology products maker Medicis Pharmaceutical (NYSE: MRX) soared 38% today after Canada's largest public drugmaker Valeant Pharmaceuticals (NYSE: VRX) agreed to acquire it for about $2.6 billion.

So what: The deal values Medicis at $44 per share and represents a whopping 39% premium to its closing price on Friday. Valeant is making the move to expand its presence in the skin care industry, and judging by its own stock's 15% pop today, Mr. Market seems quite pleased with the price it's paying to do it.

Now what: The transaction, which is expected to close in the first half of 2013, will create the dominant company in the U.S. dermatology space: Medicis led the market in sales last year, and Valeant was third. "The acquisition of Medicis represents a significant next step in our journey to become the leader in dermatology by strengthening Valeant's presence in acne, actinic keratosis, aesthetic injectables and anti-virals, among others," said Valeant CEO Michael Pearson. So while Medicis shares might be all popped out, Valeant's increasing scale in the skin care industry might be a source of market-topping returns going forward.

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