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’s (TS) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Tenaris manufactures and supplies steel pipe products and related services for the world’s energy industry. In 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.

The rating of Dril-Quip, Inc. (DRQ) declines this week 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. 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.

Helix Energy Solutions Group, Inc. (HLX) experiences a ratings drop this week, going from last week’s D to an F. 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.