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.

Considering these trends, value investing is clearly one of the most preferred ways to find strong stocks in any type of market. Value investors rely on traditional forms of analysis on key valuation metrics to find stocks that they believe are undervalued, leaving room for profits.

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 company value investors might notice is International Consolidated Airlines Group (ICAGY Quick QuoteICAGY - Free Report) . ICAGY is currently sporting a Zacks Rank of #2 (Buy), as well as an A grade for Value. The stock has a Forward P/E ratio of 11. This compares to its industry's average Forward P/E of 16.11. Over the past year, ICAGY's Forward P/E has been as high as 36.78 and as low as -3.16, with a median of 16.08.

We should also highlight that ICAGY has a P/B ratio of 1.52. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. This stock's P/B looks solid versus its industry's average P/B of 3.32. Over the past 12 months, ICAGY's P/B has been as high as 4.70 and as low as 1.09, with a median of 1.47.

Another great Transportation - Airline stock you could consider is United Airlines (UAL Quick QuoteUAL - Free Report) , which is a # 2 (Buy) stock with a Value Score of A.

United Airlines sports a P/B ratio of 2.81 as well; this compares to its industry's price-to-book ratio of 3.32. In the past 52 weeks, UAL's P/B has been as high as 4.68, as low as 2.01, with a median of 3.

Value investors will likely look at more than just these metrics, but the above data helps show that International Consolidated Airlines Group and United Airlines are likely undervalued currently. And when considering the strength of its earnings outlook, ICAGY and UAL sticks out as one of the market's strongest value stocks.