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

Numerex Corp. Class A (NMRX) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Numerex develops and markets a variety of communication and information products and services. In Portfolio Grader’s specific subcategories of Earnings Growth, Earnings Momentum and Margin Growth, NMRX also gets an F. The trailing PE Ratio for the stock is 747.90. To get an in-depth look at NMRX, get Portfolio Grader’s complete analysis of NMRX stock.

Wi-LAN Inc. (WILN) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Wi-LAN develops, acquires, and licenses a range of intellectual property that drives products in communications and consumer electronics markets. The stock gets F’s in Earnings Growth and Equity. For a full analysis of WILN stock, visit Portfolio Grader.

The rating of EXFO Inc. (EXFO) slips from a D to an F. EXFO 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 stock gets F’s in Earnings Revisions, Earnings Surprise and Sales Growth. The stock’s trailing PE Ratio is 120.50. For more information, get Portfolio Grader’s complete analysis of EXFO 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.