This week, 3 Wireless Telecommunication Services stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This is a rough week for SBA Communications Corporation (SBAC). The company’s rating falls to D from the previous week’s C. SBA Communications Corporation owns and operates wireless communications infrastructure in the United States. The company also gets F’s in earnings revisions and earnings momentum. For more information, get Portfolio Grader’s complete analysis of SBAC stock.

TIM Participacoes S.A. Sponsored ADR (TSU) earns a F this week, moving down from last week’s grade of D. TIM Participacoes S.A. Sponsored ADR is a mobile telecommunications services provider in Brazil. The company also gets F’s in sales growth, earnings growth, and free cash flow. For more information, get Portfolio Grader’s complete analysis of TSU stock.

Boingo Wireless, Inc. (WIFI) is having a tough week. The company’s rating falls from a C to a D. Boingo Wireless, Inc. installs, manages, and operates wireless network infrastructure to provide Wi-Fi services at its managed and operated hotspots. The company also gets F’s in earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of WIFI 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.