This week, these five stocks have the worst ratings in Operating Margin, one of the eight Fundamental Categories on Portfolio Grader.

Kingtone Wirelessinfo Solution Holding Ltd. Sponsored ADR (KONE) operates as a developer and provider of mobile enterprise solutions in the People’s Republic of China. The company also gets F’s in sales growth, operating margin growth, and earnings growth. For more information, get Portfolio Grader’s complete analysis of KONE stock.

China Ceramics Co. Ltd. (CCCL) engages in the manufacture and sale of ceramic tiles used for exterior siding, interior flooring, and design in residential and commercial buildings. The company also gets F’s in sales growth, operating margin growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of CCCL stock.

Nordic American Offshore Ltd.. The company also gets F’s in sales growth, operating margin growth, earnings revisions, and earnings surprise. For more information, get Portfolio Grader’s complete analysis of NAO stock.

Eni SpA Sponsored ADR (E) works in oil and gas exploration and production, gas marketing operations, management of gas infrastructures, power generation, petrochemicals and oil field services. The company also gets F’s in sales growth, operating margin growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of E stock.

Cabot Oil & Gas Corporation (COG) is an independent company that develops, explores, produces and markets natural gas, and transports, stores, and gathers it for resale. The company also gets F’s in sales growth, operating margin growth, and earnings growth. For more information, get Portfolio Grader’s complete analysis of COG 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.