This week, the ratings of four energy services stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Tenaris S.A. Sponsored ADR (TS) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Tenaris manufactures and supplies steel pipe products and related services for the world’s energy industry. For Portfolio Grader’s specific subcategory of Sales Growth, TS also gets an F. Shares of the stock have been trading at an exceptionally rapid pace, up fourfold from the week prior. For more information, get Portfolio Grader’s complete analysis of TS stock.

The rating of Dril-Quip, Inc. (DRQ) slips from a C to a D. Dril-Quip designs, manufactures, sells, and services offshore drilling and production equipment to be used in deepwater, harsh environment, and severe service applications. Shares of the stock are changing hands at twice the rate they were a week ago. To get an in-depth look at DRQ, get Portfolio Grader’s complete analysis of DRQ stock.

Hornbeck Offshore Services, Inc. (HOS) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Hornbeck Offshore Services provides marine transportation services to the offshore oil and gas industry. The stock gets F’s in Earnings Revisions and Cash Flow. As of Dec. 11, 2014, 11% of outstanding Hornbeck Offshore Services, Inc. shares were held short. Shares of the stock have been changing hands at an unusually rapid pace, three times the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of HOS stock.

Helix Energy Solutions Group, Inc. (HLX) earns an F this week, moving down from last week’s grade of D. Helix Energy Solutions is a marine contractor and operator of offshore oil and gas properties and production facilities. The stock gets F’s in Cash Flow and Margin Growth. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. To get an in-depth look at HLX, get Portfolio Grader’s complete analysis of HLX 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.