The ratings of 4 Health Care Equipment & Supplies stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Spectranetics Corporation (SPNC) experiences a ratings drop this week, going from last week’s C to a D. Spectranetics Corporation develops, manufactures, markets and distributes single-use medical devices used in minimally invasive procedures within the cardiovascular system, many of which are used with its proprietary excimer laser system. The company also gets F’s in earnings revisions and return on equity. For more information, get Portfolio Grader’s complete analysis of SPNC stock.

This week, Oxford Immunotec Global PLC (OXFD) drops from a C to a D rating. The company also gets F’s in earnings revisions and return on equity. For more information, get Portfolio Grader’s complete analysis of OXFD stock.

Slipping from a D to a F rating, Sientra, Inc. (SIEN) takes a hit this week. The company also gets F’s in sales growth, earnings revisions, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of SIEN stock.

Second Sight Medical Products, Inc. (EYES) slips from a D to a F this week. The company also gets F’s in earnings revisions, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of EYES 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.