This week, the overall grades of five communications equipment stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

ARRIS Group, Inc.’s (ARRS) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. ARRIS is a global communications technology company specializing in the design and engineering of broadband network solutions. For more information, get Portfolio Grader’s complete analysis of ARRS stock.

Applied Optoelectronics, Inc. (AAOI) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a C (“sell”). The stock gets F’s in Earnings Surprise and Cash Flow. As of May 21, 2015, 12.6% of outstanding Applied Optoelectronics, Inc. shares were held short. The trailing PE Ratio for the stock is 66.00. To get an in-depth look at AAOI, get Portfolio Grader’s complete analysis of AAOI stock.

Dragonwave Inc. (DRWI) experiences a ratings drop this week, going from last week’s C to a D. DragonWave is a producer of high-capacity packet microwave solutions which support networking and other data transmission needs. The stock gets F’s in Equity and Cash Flow. For more information, get Portfolio Grader’s complete analysis of DRWI stock.

The rating of Clearfield, Inc. (CLFD) slips from a D to an F. Clearfield offers telecommunications equipment and products in the United States. The stock gets F’s in Earnings Growth, Earnings Momentum and Sales Growth. As of May 21, 2015, 10.2% of outstanding Clearfield, Inc. shares were held short. Shares of the stock have been trading at an exceptionally rapid pace, up threefold from the week prior. The stock’s trailing PE Ratio is 51.00. To get an in-depth look at CLFD, get Portfolio Grader’s complete analysis of CLFD stock.

The rating of Sonus Networks, Inc. (SONS) declines this week from a C to a D. Sonus Networks provides voice infrastructure solutions for wireline and wireless service providers. For more information, get Portfolio Grader’s complete analysis of SONS 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.