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.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 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 company value investors might notice is Stellantis (STLA). STLA is currently sporting a Zacks Rank of #1 (Strong Buy), as well as an A grade for Value. The stock holds a P/E ratio of 5.02, while its industry has an average P/E of 12.94. STLA's Forward P/E has been as high as 7.27 and as low as 4.38, with a median of 5.37, all within the past year.We also note that STLA holds a PEG ratio of 0.24. This figure is similar to the commonly-used P/E ratio, with the PEG ratio also factoring in a company's expected earnings growth rate. STLA's PEG compares to its industry's average PEG of 0.68. Over the past 52 weeks, STLA's PEG has been as high as 4.30 and as low as 0.23, with a median of 0.27.We should also highlight that STLA has a P/B ratio of 0.69. 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 attractive against its industry's average P/B of 1.06. STLA's P/B has been as high as 1.46 and as low as 0.64, with a median of 1.10, over the past year.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. STLA has a P/S ratio of 0.39. This compares to its industry's average P/S of 0.58.Finally, our model also underscores that STLA has a P/CF ratio of 5.14. 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. STLA's P/CF compares to its industry's average P/CF of 6.13. Over the past 52 weeks, STLA's P/CF has been as high as 5.84 and as low as 3.15, with a median of 4.79.Value investors will likely look at more than just these metrics, but the above data helps show that Stellantis is likely undervalued currently. And when considering the strength of its earnings outlook, STLA sticks out at as one of the market's strongest value stocks. Zacks Names "Single Best Pick to Double" From thousands of stocks, 5 Zacks experts each have chosen their favorite to skyrocket +100% or more in months to come. From those 5, Director of Research Sheraz Mian hand-picks one to have the most explosive upside of all. You know this company from its past glory days, but few would expect that it's poised for a monster turnaround. Fresh from a successful repositioning and flush with A-list celeb endorsements, it could rival or surpass other recent Zacks' Stocks Set to Double like Boston Beer Company which shot up +143.0% in a little more than 9 months and Nvidia which boomed +175.9% in one year.Free: See Our Top Stock and 4 Runners Up >>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 Stellantis N.V. (STLA): Free Stock Analysis Report To read this article on Zacks.com click here.