Here at Zacks, we focus on our proven ranking system, which places an emphasis on earnings estimates and estimate revisions, to find winning stocks. But we also understand that investors develop their own strategies, so we are constantly looking at the latest trends in value, growth, and momentum to find strong companies for our readers.

Of these, value investing is easily one of the most popular ways to find great stocks in any market environment. Value investors use tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.

Zacks has developed the innovative Style Scores system to highlight stocks with specific traits. For example, value investors will be interested in stocks with great grades in the "Value" category. When paired with a high Zacks Rank, "A" grades in the Value category are among the strongest value stocks on the market today.

Siga Technologies (SIGA Quick QuoteSIGA - Free Report) is a stock many investors are watching right now. SIGA is currently holding a Zacks Rank of #2 (Buy) and a Value grade of A.

Value investors also love the P/S ratio, which is calculated by simply dividing a stock's price with the company's sales. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. SIGA has a P/S ratio of 2.57. This compares to its industry's average P/S of 3.2.

Finally, investors should note that SIGA has a P/CF ratio of 5.21. This metric takes into account a company's operating cash flow and can be used to find stocks that are undervalued based on their solid cash outlook. SIGA's P/CF compares to its industry's average P/CF of 9.18. Over the past year, SIGA's P/CF has been as high as 10.16 and as low as -99.75, with a median of 6.41.

These figures are just a handful of the metrics value investors tend to look at, but they help show that Siga Technologies is likely being undervalued right now. Considering this, as well as the strength of its earnings outlook, SIGA feels like a great value stock at the moment.