For the current week, the overall ratings of three Communications Equipment stocks are worse, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Black Box‘s (NASDAQ:BBOX) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Black Box is a network infrastructure services provider that offers one-source network infrastructure services for communications systems. In Portfolio Grader’s specific subcategories of Earnings Surprise, Cash Flow, Margin Growth, and Sales Growth, BBOX also gets F’s. For a full analysis of BBOX stock, visit Portfolio Grader.

The rating of Globecomm Systems (NASDAQ:GCOM) declines this week from a C to a D. Globecomm Systems provides end-to-end, value-added satellite-based communications solutions. The stock also gets an F in Earnings Surprise. As of Sept. 13, 10.7% of outstanding Globecomm Systems shares were held short. To get an in-depth look at GCOM, get Portfolio Grader’s complete analysis of GCOM stock.

Mitel Networks‘s (NASDAQ:MITL) rating weakens this week, dropping to a D versus last week’s C. Mitel Networks is a provider of communications solutions for organizations. The stock gets F’s in Earnings Revisions and Earnings Surprise. The stock price has dropped 20.8% over the past month, worse than the 3.1% increase the Nasdaq has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of MITL 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.