This week, the ratings of three Wireless Telecom stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Telephone & Data Systems (NYSE:TDS) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Telephone and Data Systems is a telecommunications service company. In Portfolio Grader’s specific subcategories of Earnings Momentum, Earnings Surprise, and Cash Flow, TDS also gets an F. For more information, get Portfolio Grader’s complete analysis of TDS stock.

TIM Participacoes (NYSE:TSU) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). TIM Participacoes is a mobile telecommunications services provider in Brazil. The stock gets F’s in Earnings Momentum and Margin Growth. The stock price has dropped 8.1% over the past month, worse than the 3.7% increase the S&P 500 has seen over the same period of time. To get an in-depth look at TSU, get Portfolio Grader’s complete analysis of TSU stock.

The rating of SK Telecom (NYSE:SKM) slips from a C to a D. SK Telecom operates primarily in South Korea as a provider of wireless telecommunications. The stock gets F’s in Earnings Revisions and Sales Growth. For more information, get Portfolio Grader’s complete analysis of SKM 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.