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.

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 fundamental analysis and traditional valuation metrics to find stocks that they believe are being undervalued by the market at large.

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 YPF Sociedad Anonima (YPF Quick QuoteYPF - Free Report) . YPF is currently sporting a Zacks Rank of #2 (Buy) and an A for Value. The stock has a Forward P/E ratio of 2.91. This compares to its industry's average Forward P/E of 7.86. YPF's Forward P/E has been as high as 4.48 and as low as 1.55, with a median of 2.61, all within the past year.

Value investors also use the P/S ratio. The P/S ratio is is calculated as price divided by sales. This is a prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. YPF has a P/S ratio of 0.23. This compares to its industry's average P/S of 0.51.

These are just a handful of the figures considered in YPF Sociedad Anonima'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 YPF is an impressive value stock right now.