The ratings of four energy services stocks are down this week, according to the Portfolio Grader database. 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. TS also rates an F in Portfolio Grader’s specific subcategory of Sales Growth. For more information, get Portfolio Grader’s complete analysis of TS stock.

Helix Energy Solutions Group, Inc. (HLX) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). 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. To get an in-depth look at HLX, get Portfolio Grader’s complete analysis of HLX 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. For a full analysis of DRQ stock, visit Portfolio Grader.

Hornbeck Offshore Services, Inc. (HOS) earns an F this week, moving down from last week’s grade of D. 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. For more information, get Portfolio Grader’s complete analysis of HOS 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.