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 tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.

On top of the Zacks Rank, investors can also look at our innovative Style Scores system to find stocks with specific traits. For example, value investors will want to focus on the "Value" category. Stocks with high Zacks Ranks and "A" grades for Value will be some of the highest-quality value stocks on the market today.

One stock to keep an eye on is Diana Shipping (DSX). DSX is currently sporting a Zacks Rank of #2 (Buy) and an A for Value. The stock is trading with P/E ratio of 6.41 right now. For comparison, its industry sports an average P/E of 7.89. Over the past year, DSX's Forward P/E has been as high as 19.84 and as low as 6.28, with a median of 11.83.

Finally, investors should note that DSX has a P/CF ratio of 3.92. This figure highlights a company's operating cash flow and can be used to find firms that are undervalued when considering their impressive cash outlook. This stock's P/CF looks attractive against its industry's average P/CF of 11.40. Over the past 52 weeks, DSX's P/CF has been as high as 4.37 and as low as 2.40, with a median of 3.07.

If you're looking for another solid Transportation - Shipping value stock, take a look at Navios Maritime Partners (NMM). NMM is a # 1 (Strong Buy) stock with a Value score of A.

Additionally, Navios Maritime Partners has a P/B ratio of 0.54 while its industry's price-to-book ratio sits at 2.69. For NMM, this valuation metric has been as high as 0.56, as low as 0.25, with a median of 0.31 over the past year.

Value investors will likely look at more than just these metrics, but the above data helps show that Diana Shipping and Navios Maritime Partners are likely undervalued currently. And when considering the strength of its earnings outlook, DSX and NMM sticks out as one of the market's strongest value stocks.

Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report