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”).

This week, Tenaris S.A. Sponsored ADR (TS) falls to a D (“sell”), worse than last week’s grade of C (“hold”). 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. For more information, get Portfolio Grader’s complete analysis of TS stock.

Dril-Quip, Inc. (DRQ) earns a D this week, falling from last week’s grade of C. Dril-Quip designs, manufactures, sells, and services offshore drilling and production equipment to be used in deepwater, harsh environment, and severe service applications. To get an in-depth look at DRQ, get Portfolio Grader’s complete analysis of DRQ stock.

Hornbeck Offshore Services, Inc.’s (HOS) rating falls this week to an F (“strong sell”), down from last week’s 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. For more information, get Portfolio Grader’s complete analysis of HOS stock.

This week, Helix Energy Solutions Group, Inc. (HLX) drops from a D to an F rating. 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.

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.