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

Midstates Petroleum Company, Inc. (MPO) is an independent exploration and production company. The company also gets F’s in sales growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of MPO stock.

Triangle Petroleum Corporation. (TPLM) acquires, explores, and develops mineral properties. The company also gets F’s in sales growth, operating margin growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of TPLM stock.

Natural Resource Partners L.P. (NRP) owns and manages coal properties in Appalachia, the Illinois Basin, and the Western United States. The company also gets F’s in operating margin growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of NRP stock.

Chesapeake Energy Corporation (CHK) explores, develops and acquires properties for the production of natural gas and crude oil from underground reservoirs. The company also gets F’s in sales growth, operating margin growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of CHK stock.

Comstock Resources, Inc. (CRK) is an independent energy company that acquires, explores, develops, and produces oil and natural gas in the United States. The company also gets F’s in sales growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of CRK 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.