NEW YORK ( TheStreet) -- Shares of Siga Technologies (Nasdaq: SIGA) were gapping up Tuesday morning with an open price 20.1% higher than Friday's closing price. The stock closed at $11.40 Friday and opened today's trading at $13.69. The average volume for Siga has been 338,500 shares per day over the past 30 days. Siga has a market cap of $546.2 million and is part of the health care sector and drugs industry. Shares are down 18.6% year to date as of the close of trading on Friday. SIGA Technologies, Inc., a bio-defense company, engages in the discovery, development, and commercialization of products for use in defense against biological warfare agents comprising smallpox and arenaviruses. TheStreet Ratings rates Siga as a hold. The company's strengths can be seen in multiple areas, such as its robust revenue growth, largely solid financial position with reasonable debt levels by most measures and solid stock price performance. However, as a counter to these strengths, we also find weaknesses including unimpressive growth in net income, weak operating cash flow and feeble growth in the company's earnings per share. You can view the full Siga Ratings Report. Get more investment ideas from our investment research center.