Here at Zacks, our focus is on the proven Zacks Rank system, which emphasizes earnings estimates and estimate revisions to find great stocks. Nevertheless, we are always paying attention to the latest value, growth, and momentum trends to underscore strong picks.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.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 to watch right now is United States Steel (X). X is currently sporting a Zacks Rank of #2 (Buy), as well as a Value grade of A. The stock is trading with a P/E ratio of 3.46, which compares to its industry's average of 4.90. Over the last 12 months, X's Forward P/E has been as high as 79.88 and as low as -271.94, with a median of 3.75.Another valuation metric that we should highlight is X's P/B ratio of 1.25. 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. X's current P/B looks attractive when compared to its industry's average P/B of 1.84. Within the past 52 weeks, X's P/B has been as high as 1.65 and as low as 0.40, with a median of 1.05.Value investors also use the P/S ratio. The P/S ratio is is calculated as price divided by sales. Some people prefer this metric because sales are harder to manipulate on an income statement. This means it could be a truer performance indicator. X has a P/S ratio of 0.54. This compares to its industry's average P/S of 0.56.These are just a handful of the figures considered in United States Steel'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 X is an impressive value stock right now. Zacks' Top Picks to Cash in on Artificial Intelligence In 2021, this world-changing technology is projected to generate $327.5 billion in revenue. Now Shark Tank star and billionaire investor Mark Cuban says AI will create "the world's first trillionaires." Zacks' urgent special report reveals 3 AI picks investors need to know about today.See 3 Artificial Intelligence Stocks With Extreme Upside Potential>>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 United States Steel Corporation (X): Free Stock Analysis Report To read this article on Zacks.com click here.