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”).

Given Imaging (NASDAQ:GIVN) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Given Imaging has developed a proprietary wireless imaging system that allows a medical professional to examine the gastrointestinal tract. In Portfolio Grader’s specific subcategory of Earnings Surprise, GIVN also gets an F. The stock has a trailing PE Ratio of 35.10. To get an in-depth look at GIVN, get Portfolio Grader’s complete analysis of GIVN stock.

This is a rough week for Greatbatch (NYSE:GB). The company’s rating falls to D from the previous week’s C. Greatbatch develops and manufactures power sources, feedthroughs, and wet tantalum capacitors used in implantable medical devices. The stock gets F’s in Earnings Growth, Earnings Momentum, and Margin Growth.

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

Tornier’s (NASDAQ:TRNX) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). Tornier designs, outsources the manufacture of and markets orthopedic products. The stock gets F’s in Earnings Momentum and Earnings Revisions. The stock price has fallen 7.4% over the past month, worse than the 4.3% increase the Nasdaq has seen over the same period of time. To get an in-depth look at TRNX, get Portfolio Grader’s complete analysis of TRNX 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.