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. To get an in-depth look at TDS, get Portfolio Grader’s complete analysis of TDS stock.

TIM Participacoes‘ (NYSE:TSU) rating falls this week to a F (“strong sell”), down from last week’s 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 9.6% over the past month, worse than the 2% decrease the S&P 500 has seen over the same period of time.

For a full analysis of TSU stock, visit Portfolio Grader.

SK Telecom (NYSE:SKM) gets weaker ratings this week as last week’s C drops 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. To get an in-depth look at SKM, 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.