This week, four chemicals stocks are improving their overall ratings on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

Platform Specialty Products Corp.’s (PAH) grade is moving up to a B (“buy”) this week from last week’s C (“hold”). In Portfolio Grader’s specific subcategory of Earnings Surprise, PAH also gets an A. For more information, get Portfolio Grader’s complete analysis of PAH stock.

This week, Burcon NutraScience Corporation’s (BUR) ratings are up from a C last week to a B. Burcon NutraScience specializes in nutrition, health and wellness in the field of functional and renewable plant proteins. For more information, get Portfolio Grader’s complete analysis of BUR stock.

The rating of Valspar Corporation (VAL) moves up this week, rising from a C to a B. Valspar is a coating and paint manufacturer and distributor. For more information, get Portfolio Grader’s complete analysis of VAL stock.

This is a strong week for Potash Corporation of Saskatchewan Inc. (POT). The company’s rating climbs to B from the previous week’s C. Potash Corporation of Saskatchewan produces potash, phosphate, and nitrogen to the agricultural and industrial industries worldwide. For more information, get Portfolio Grader’s complete analysis of POT stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.