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 Internet security software specialist VirnetX (AMEX: VHC) surged 10% in intraday trading Thursday on a spike in volume.

So what: At the time of publication, about 1.2 million of VirnetX's shares have already changed hands, versus the average volume of roughly 960,000 shares. I couldn't find any specific news driving today's heavy rally, but when you couple VirnetX's high beta and small size with the fact that it's widely considered an ideal takeover target, it doesn't take a whole lot of buzz to send the stock climbing.

Now what: For this Fool, VirnetX is now flying too high for comfort. The stock is already up about 20% since its big plunge in November and, of course, has returned more than 350% over the past year. With patent-infringement suits still out against the likes of Cisco (Nasdaq: CSCO) and Apple (Nasdaq: AAPL), VirnetX could certainly keep soaring, but I'd rather wait until Mr. Market is less optimistic about the outcomes.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Apple is a Motley Fool Stock Advisor recommendation, and the Fool owns shares of it. 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. The Fool's disclosure policy always gets a perfect score.