While the proven Zacks Rank places an emphasis on earnings estimates and estimate revisions to find strong stocks, we also know that investors tend to develop their own individual strategies. With this in mind, we are always looking at value, growth, and momentum trends to discover great companies.

Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.

Luckily, Zacks has developed its own Style Scores system in an effort to find stocks with specific traits. Value investors will be interested in the system's "Value" category. Stocks with both "A" grades in the Value category and high Zacks Ranks are among the strongest value stocks on the market right now.

One stock to keep an eye on is SkyWest (SKYW). SKYW is currently holding a Zacks Rank of #1 (Strong Buy) and a Value grade of A. The stock holds a P/E ratio of 11.08, while its industry has an average P/E of 16.57. Over the last 12 months, SKYW's Forward P/E has been as high as 14.41 and as low as 9.16, with a median of 11.06.

Finally, investors will want to recognize that SKYW has a P/CF ratio of 5.96. 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. This company's current P/CF looks solid when compared to its industry's average P/CF of 12. Within the past 12 months, SKYW's P/CF has been as high as 7.64 and as low as 5.04, with a median of 6.31.

United Airlines (UAL) may be another strong Transportation - Airline stock to add to your shortlist. UAL is a # 1 (Strong Buy) stock with a Value grade of A.

United Airlines is trading at a forward earnings multiple of 8.08 at the moment, with a PEG ratio of 0.69. This compares to its industry's average P/E of 16.57 and average PEG ratio of 0.83.

Over the last 12 months, UAL's P/E has been as high as 9.45, as low as 3.63, with a median of 5.01, and its PEG ratio has been as high as 1.13, as low as 0.41, with a median of 0.65.

Furthermore, United Airlines holds a P/B ratio of 2.76 and its industry's price-to-book ratio is 5.15. UAL's P/B has been as high as 2.95, as low as 1.18, with a median of 1.84 over the past 12 months.

These are just a handful of the figures considered in SkyWest and United Airlines's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that SKYW and UAL is an impressive value stock right now.

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