This week, the overall grades of 4 Communications Equipment stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

F5 Networks, Inc.’s (FFIV) rating weakens this week, dropping to a D versus last week’s C. F5 Networks, Inc. provides integrated Internet traffic management solutions designed to improve the availability and performance of mission-critical Internet-based servers and applications. For more information, get Portfolio Grader’s complete analysis of FFIV stock.

This is a rough week for ADTRAN, Inc. (ADTN). The company’s rating falls to D from the previous week’s C. ADTRAN, Inc. designs, manufactures, markets and services network access solutions for communications networks for providers of communications services and small- and mid-sized businesses. For more information, get Portfolio Grader’s complete analysis of ADTN stock.

Norsat International Inc. (NSAT) earns a D this week, moving down from last week’s grade of C. For more information, get Portfolio Grader’s complete analysis of NSAT stock.

This week, AudioCodes Ltd.’s (AUDC) rating worsens to a D from the company’s C rating a week ago. AudioCodes Ltd. designs, develops, and markets products for voice and data over packet networks. The company also gets F’s in sales growth and operating margin growth. For more information, get Portfolio Grader’s complete analysis of AUDC 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.