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 Zeltiq Aesthetics (NASDAQ:ZLTQ) are enjoying their third day of double-digit gains in the past two weeks today, after the company announced a secondary offering of 4.5 million shares held by several venture capital firms. Shares are up 15% as of this writing, but have held steady at a minimum 14% gain all afternoon.

So what: Last night, Zeltiq filed a prospectus to sell shares, as mentioned earlier. The timing is fortuitous for the offering parties, as the company is coming off of a huge earnings beat at the end of October. Zeltiq itself won't benefit from this sale, as the selling stockholders are: Advanced Technology Ventures, Aisling Capital, and Venrock Associates. Advanced owned 22% of the company's shares prior to the offering; Aisling owned 11%; and Venrock owned 17%. After reducing their stakes, the three companies will have new stakes of 12%, 10%, and 15%, respectively. Current shareholders won't be diluted, which could explain why there's so much excitement today -- more than seven times the normal number of shares have already traded today, but the stock's volume of 2.8 million shares doesn't fully account for the offering.

Now what: What's unusual about this response is that the 4.5 million shares were offered at a price of $13 per share, and the offering's underwriters can purchase up to 675,000 more shares within 30 days. The stock's current price of roughly $15.60 represents a 17% premium over that offering price, so today's buyers are either absolutely certain in Zeltiq's long-term potential or are headed for a rough patch once these lower-priced shares hit the market. The company's last earnings report certainly gave investors a lot of reason for excitement, but this pop seems a bit out of place. That doesn't mean it's a bad buy, but you should make sure to keep your eye on this company to flesh out your investing thesis, if you're not already doing so.

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