This week, the ratings of 3 Wireless Telecommunication Services stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Slipping from a C to a D rating, SBA Communications Corporation (SBAC) takes a hit this week. 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.

America Movil SAB de CV Sponsored ADR Class L (AMX) declines this week from a D to a F. America Movil SAB de CV Sponsored ADR Class L provides wireless and fixed-communications services throughout Latin America. The company also gets F’s in sales growth, operating margin growth, earnings revisions, and earnings surprise. For more information, get Portfolio Grader’s complete analysis of AMX stock.

VimpelCom Ltd. Sponsored ADR (VIP) is having a tough week. The company’s rating falls from a D to a F. VimpelCom Ltd. Sponsored ADR provides an integrated telecommunications service through a range of wireless, fixed, and broadband technologies throughout the world. The company also gets F’s in sales growth, earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of VIP 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.