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

DryShips Inc. (DRYS) is the owner and operator of a drybulk fleet. The company also gets F’s in sales growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of DRYS stock.

Denbury Resources Inc. (DNR) is an independent company that acquires and develops oil and natural gas properties. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of DNR 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.

Gastar Exploration, Inc. (GST) is a natural gas exploration company. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of GST 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 sales growth, operating margin growth, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of NRP 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.