This week, the energy services, marine, electrical equipment, construction and engineering and medical technology sectors rank lowest on the Portfolio Grader database.

The energy services sector is dragging, with 89% of its stocks (51 out of 57) rated a “sell”. With an overall grade of F, CARBO Ceramics (CRR), Transocean (RIG) and Seadrill (SDRL) are weighing down the sector.

With 86% of its stocks (6 out of 7) rated “sell,” the marine sector is struggling this week. Out of the marine stocks, Diana Shipping (DSX) and Seaspan Corporation (SSW) are near the bottom of the sector with D’s. Kirby Corporation (KEX) also ranks a weak F.

The electrical equipment sector is lagging this week with 65% of its stocks (15 out of 23) rated a “sell”. Among electrical equipment stocks, General Cable Corporation (BGC), Encore Wire Corporation (WIRE) and ABB Ltd. Sponsored ADR (ABB) are lingering near the bottom with grades of F.

The construction and engineering sector is trailing behind others this week, with 62% of its stocks (13 out of 21) rated a “sell”. KBR, Inc. (KBR), Empresas ICA SAB de CV Sponsored ADR (ICA) and Jacobs Engineering Group (JEC) are dragging down the sector overall, each earning a low grade of F.

The medical technology sector looks weak, with 55% of its stocks (6 out of 11) rated a “sell”. Allscripts Healthcare Solutions, Inc. (MDRX), Computer Programs and Systems, Inc. (CPSI) and Medidata Solutions, Inc. (MDSO) are all currently earning D’s.

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.