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 oil and gas explorer Hyperdynamics (AMEX: HDY) sank as much as 20% in early Tuesday trading on extraordinarily high volume.

So what: At the time of publication, nearly 5 million Hyperdynamics shares had already changed hands, versus the three-month average volume of about 1.5 million shares. I couldn't pinpoint any company-specific news driving today's heavy sell-off, but when you couple the stock's beta of 2.7 with the risks recently outlined by my fellow Fool Toby Shute, sharp one-day drops shouldn't come as a surprise.

Now what: Hyperdynamics remains just too speculative for most portfolios. Even with today's double-digit plunge, the shares are up more than an astonishing 500% over the past six months and, according to Toby's valuation work, are being valued at about $4 per risked barrel. While Hyperdynamics's prospects in offshore Guinea are certainly attractive, I'd wait until Mr. Market is a lot less optimistic about them before jumping in.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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