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 bio-defense specialist SIGA Technologies (Nasdaq: SIGA) sank more than 15% in intraday trading Thursday after its quarterly results came in well below Wall Street expectations.

So what: For the fourth quarter, SIGA reported an ugly loss of $13.58 million, or $0.29 per share, on revenue of $3.06 million, while analysts were projecting a profit of $0.03 per share on a top-line of $10.03 million. The shares had been rising in recent weeks on the expectation of a big government contract win to supply millions of doses of smallpox antiviral, but today's operating results, coupled with no overly bullish comments from management regarding the potential contract, has Mr. Market understandably disappointed.

Now what: Last month, I wrote that SIGA wasn't suitable for most Fools, and today's plunge hasn't changed that. While a Wedbush Securities analyst recently noted that the government contract could potentially result in a whopping $2.8 billion in sales, it's a bet best suited for less risk-averse investors. The stock is still up more than 100% from its June lows and trades at a price-to-sales ratio above 30, so there seems to be plenty of downside if that gamble goes wrong.

Interested in more info on SIGA? 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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