On the Portfolio Grader database this week, the Communications Equipment, Metals and Mining, Marine, Technology Equipment, and Semiconductor sectors are among the worst.

The Communications Equipment sector is lagging this week with 69% of its stocks (24 out of 35) rated a “sell”. Out of the Communications Equipment stocks, Adtran (NASDAQ:ADTN), Finisar (NASDAQ:FNSR), and ViaSat Inc. (NASDAQ:VSAT) are near the bottom with F’s.

The Metals and Mining sector looks weak, with 67% of its stocks (61 out of 91) rated a “sell”. Walter Energy Inc. (NYSE:WLT), Thompson Creek Metals (NYSE:TC), and Cliffs Natural Resources (NYSE:CLF) are all currently earning F’s. Cliffs Natural Resources is performing worst overall in the sector, with a 38.6% decline over the last 12 months.

The Marine sector is dragging, with 63% of its stocks (5 out of 8) rated a “sell”. Kirby Corp. (NYSE:KEX), DryShips (NASDAQ:DRYS), and Diana Shipping (NYSE:DSX) are dragging down the sector overall, each earning a low grade of D.

The Technology Equipment sector is trailing behind others this week, with 61% of its stocks (31 out of 51) rated a “sell”. TTM Technologies (NASDAQ:TTMI), AVX (NYSE:AVX), and Universal Display (NASDAQ:PANL) are pushing the sector down with F grades. Universal Display is the worst performer in this sector, with a 18.9% decline in the last 12 months.

With 60% of its stocks (49 out of 81) rated “sell,” the Semiconductor sector is struggling this week. With an overall grade of F, International Rectifier (NYSE:IRF), PMC-Sierra (NASDAQ:PMCS), and Intersil (NASDAQ:ISIL) are weighing down the sector.

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.