The ratings of three medical devices stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Derma Sciences, Inc.’s (DSCI) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). Derma Sciences markets and sells a range of skin care, wound management, and specialty securement devices. In Portfolio Grader’s specific subcategories of Equity, Cash Flow and Sales Growth, DSCI also gets an F. To get an in-depth look at DSCI, get Portfolio Grader’s complete analysis of DSCI stock.

This week, St. Jude Medical, Inc. (STJ) falls to a D (“sell”), worse than last week’s grade of C (“hold”). St. Jude Medical makes and distributes cardiovascular medical devices. Shares of the stock have been exchanging at an usually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of STJ stock.

Baxter International’s (BAX) rating weakens this week, dropping to a D versus last week’s C. Baxter International develops, manufactures and markets products related to hemophilia, immune disorders, infectious diseases, kidney disease, trauma, and other chronic and acute medical conditions. The stock also rates an F in Earnings Revisions. To get an in-depth look at BAX, get Portfolio Grader’s complete analysis of BAX 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.