The proven Zacks Rank system focuses on earnings estimates and estimate revisions to find winning stocks. Nevertheless, we know that our readers all have their own perspectives, so we are always looking at the latest trends in value, growth, and momentum to find 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 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 company to watch right now is Markel (MKL). MKL 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 16.32, which compares to its industry's average of 29.95. Over the past year, MKL's Forward P/E has been as high as 21.02 and as low as 15.56, with a median of 18.75.We should also highlight that MKL has a P/B ratio of 1.22. 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. MKL's current P/B looks attractive when compared to its industry's average P/B of 1.43. Over the past 12 months, MKL's P/B has been as high as 1.36 and as low as 1.15, with a median of 1.27.Stewart Information Services (STC) may be another strong Insurance - Property and Casualty stock to add to your shortlist. STC is a # 1 (Strong Buy) stock with a Value grade of A.Stewart Information Services sports a P/B ratio of 1.37 as well; this compares to its industry's price-to-book ratio of 1.43. In the past 52 weeks, STC's P/B has been as high as 1.77, as low as 1.26, with a median of 1.47.Value investors will likely look at more than just these metrics, but the above data helps show that Markel and Stewart Information Services are likely undervalued currently. And when considering the strength of its earnings outlook, MKL and STC sticks out as one of the market's strongest value stocks. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 5 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>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 Markel Corporation (MKL): Free Stock Analysis Report Stewart Information Services Corporation (STC): Free Stock Analysis Report To read this article on Zacks.com click here.