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.

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 stock to keep an eye on is Kaiser Aluminum (KALU Quick QuoteKALU - Free Report) . KALU is currently sporting a Zacks Rank #2 (Buy), as well as an A grade for Value. The stock is trading with P/E ratio of 13.27 right now. For comparison, its industry sports an average P/E of 15.84. Over the past year, KALU's Forward P/E has been as high as 26.64 and as low as 11.53, with a median of 14.12.

Another valuation metric that we should highlight is KALU's P/B ratio of 1.61. 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 solid versus its industry's average P/B of 2.71. KALU's P/B has been as high as 2.08 and as low as 1.07, with a median of 1.69, over the past year.

Value investors also use the P/S ratio. The P/S ratio is calculated as price divided by sales. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. KALU has a P/S ratio of 0.57. This compares to its industry's average P/S of 1.08.

Finally, investors will want to recognize that KALU has a P/CF ratio of 7.29. This metric focuses on a firm's operating cash flow and is often used to find stocks that are undervalued based on the strength of their cash outlook. This stock's P/CF looks attractive against its industry's average P/CF of 14.30. Within the past 12 months, KALU's P/CF has been as high as 8.75 and as low as 4.85, with a median of 7.04.

These figures are just a handful of the metrics value investors tend to look at, but they help show that Kaiser Aluminum is likely being undervalued right now. Considering this, as well as the strength of its earnings outlook, KALU feels like a great value stock at the moment.