For the current week, the overall ratings of five chemicals stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, PolyOne Corporation (POL) falls to a D (“sell”), worse than last week’s grade of C (“hold”). PolyOne is an international polymer services company with operations in North America, Europe, Asia, Australia, and South America. In Portfolio Grader’s specific subcategories of Earnings Growth, Earnings Momentum and Sales Growth, POL also gets an F. For more information, get Portfolio Grader’s complete analysis of POL stock.

This is a rough week for Arabian American Development Company (ARSD). The company’s rating falls to D from the previous week’s C. 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 and Earnings Surprise. To get an in-depth look at ARSD, get Portfolio Grader’s complete analysis of ARSD stock.

Marrone Bio Innovations, Inc.’s (MBII) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). The stock gets F’s in Earnings Momentum, Equity, Cash Flow and Sales Growth. Shares of the stock have been exchanging at an usually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of MBII stock.

Kraton Performance Polymers, Inc. (KRA) is having a tough week. The company’s rating falls from a D to an F. Kraton Performance Polymers produces engineered polymers and styrenic block copolymers. The stock gets F’s in Earnings Momentum and Earnings Surprise. To get an in-depth look at KRA, get Portfolio Grader’s complete analysis of KRA stock.

Huntsman Corporation (HUN) gets weaker ratings this week as last week’s C drops to a D. Huntsman manufactures differentiated and commodity chemical products. The stock gets F’s in Earnings Momentum, Earnings Revisions and Earnings Surprise. For more information, get Portfolio Grader’s complete analysis of HUN 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.