The overall ratings of three biotechnology stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Cellular Dynamics International, Inc.’s (ICEL) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. In Portfolio Grader’s specific subcategories of Equity and Cash Flow, ICEL also gets F’s. To get an in-depth look at ICEL, get Portfolio Grader’s complete analysis of ICEL stock.

Trius Therapeutics, Inc. (TSRX) earns a D this week, moving down from last week’s grade of C. Trius Therapeutics is a biopharmaceutical company. The stock gets F’s in Earnings Growth, Earnings Momentum and Equity. Cash Flow and Sales Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of TSRX stock.

The rating of Prosensa Holding NV (RNA) declines this week from a C to a D. The stock gets F’s in Equity and Sales Growth. To get an in-depth look at RNA, get Portfolio Grader’s complete analysis of RNA 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.