For the current week, the overall ratings of four Energy Services stocks are worse, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Noble Corp. (NYSE:NE) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Noble is an offshore drilling contractor, engineer, and consultant for the oil and gas industry. In Portfolio Grader’s specific subcategory of Cash Flow, NE also gets an F. Shares of the company are down 0.8% from a month ago. This is worse than the S&P 500’s 2.3% increase over the same period. For more information, get Portfolio Grader’s complete analysis of NE stock.

This week, Diamond Offshore Drilling (NYSE:DO) drops from a C to a D rating. Diamond Offshore Drilling is a global offshore oil and gas drilling contractor. The stock also gets an F in Sales Growth. For a full analysis of DO stock, visit Portfolio Grader.

Helix Energy Solutions Group (NYSE:HLX) experiences a ratings drop this week, going from last week’s C to a D. Helix Energy Solutions Group is a marine contractor and operator of offshore oil and gas properties and production facilities. The stock also rates an F in Earnings Momentum. To get an in-depth look at HLX, get Portfolio Grader’s complete analysis of HLX stock.

Dril-Quip‘s (NYSE:DRQ) rating weakens this week, dropping to a D versus last week’s C. Dril-Quip designs, manufactures, sells, and services offshore drilling and production equipment to be used in deepwater, harsh environment, and severe service applications. The stock currently has a trailing PE Ratio of 26.8. For a full analysis of DRQ 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.