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

Nokia Oyj Sponsored ADR (NOK) experiences a ratings drop this week, going from last week’s C to a D. Nokia Oyj Sponsored ADR makes mobile devices and offers Internet services that allow people to access music, maps, media, messaging and games. The company also gets F’s in earnings momentum. For more information, get Portfolio Grader’s complete analysis of NOK stock.

This week, Sonus Networks, Inc.’s (SONS) rating worsens to a F from the company’s D rating a week ago. Sonus Networks, Inc. provides voice infrastructure solutions for wireline and wireless service providers. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of SONS stock.

EXFO Inc. (EXFO) slips from a D to a F this week. EXFO Inc. is a provider of next-generation test and service assurance solutions for wireless and wireline network operators and equipment manufacturers in the global telecommunications industry. The company also gets F’s in earnings growth, earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of EXFO stock.

Lantronix, Inc. (LTRX) gets weaker ratings this week as last week’s D drops to a F. Lantronix, Inc. designs, develops, and markets network device servers. The company also gets F’s in earnings revisions, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of LTRX 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.