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, perhaps no stock market trend is more popular than value investing, which is a strategy that has proven to be successful in all sorts of market environments. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.

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.

One stock to keep an eye on is Reinsurance Group of America (RGA Quick QuoteRGA - Free Report) . RGA is currently sporting a Zacks Rank of #1 (Strong Buy) and an A for Value.

We should also highlight that RGA has a P/B ratio of 1.42. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. This company's current P/B looks solid when compared to its industry's average P/B of 1.77. RGA's P/B has been as high as 1.46 and as low as 1.14, with a median of 1.24, over the past year.

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 prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. RGA has a P/S ratio of 0.66. This compares to its industry's average P/S of 0.94.

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