The overall ratings of four Chemicals stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

The Mosaic Co.’s (NYSE:MOS) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Mosaic produces and distributes crop nutrients to the agricultural communities located in North America and other countries. In Portfolio Grader’s specific subcategory of Sales Growth, MOS also gets an F. To get an in-depth look at MOS, get Portfolio Grader’s complete analysis of MOS stock.

Intrepid Potash (NYSE:IPI) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). Intrepid Potash mines and markets potash for use as a fertilizer. The stock gets F’s in Earnings Revisions and Cash Flow. For more information, get Portfolio Grader’s complete analysis of IPI stock.

The rating of Olin Corp. (NYSE:OLN) slips from a C to a D. Olin Corporation manufactures and sells chlorine, caustic soda, sodium hydrosulfite, hydrochloric acid, hydrogen, sodium chlorate, bleach products, and potassium hydroxide. For a full analysis of OLN stock, visit Portfolio Grader.

Arabian American Development (NYSE:ARSD) experiences a ratings drop this week, going from last week’s C to a D. Arabian American Development owns and operates a petrochemical facility located in southeast Texas, which specializes in high purity petrochemical solvents and other solvent type manufacturing. The stock gets F’s in Earnings Momentum, Earnings Surprise, and Sales Growth. For more information, get Portfolio Grader’s complete analysis of ARSD 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.