This week, the overall grades of three Energy Services stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Patterson-UTI Energy (NASDAQ:PTEN) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Patterson-UTI provides land-based drilling services to major and independent oil and natural gas companies. PTEN also rates an F in Portfolio Grader’s specific subcategory of Earnings Revisions. For more information, get Portfolio Grader’s complete analysis of PTEN stock.

Tidewater‘s (NYSE:TDW) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Tidewater provides offshore service vessels and marine support services to the global offshore energy industry. The stock gets F’s in Earnings Revisions and Cash Flow. The stock currently has a trailing PE Ratio of 29.5. Over the past month, shares of TDW have declined 2.8%. This is worse than the S&P 500’s 0.6% increase for the same period. To get an in-depth look at TDW, get Portfolio Grader’s complete analysis of TDW stock.

This week, CGG Veritas‘s (NYSE:CGV) rating worsens to a D from the company’s C rating a week ago. CGG Veritas manufactures geophysical equipment and provides a range of services including seismic data acquisition and related processing and interpretation software mainly to clients in the oil and gas exploration and production industry. The stock has a trailing PE Ratio of 60.2. For a full analysis of CGV stock, visit Portfolio Grader.

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.