This week, the overall grades of three biotechnology stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Esperion Therapeutics, Inc. (ESPR) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. In Portfolio Grader’s specific subcategories of Equity and Cash Flow, ESPR also gets F’s. To get an in-depth look at ESPR, get Portfolio Grader’s complete analysis of ESPR 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 receives 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.

Ambit Biosciences Corp. (AMBI) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). The stock gets F’s in Earnings Momentum, Earnings Revisions and Equity. Cash Flow and Sales Growth also get F’s. In the past week, the volume of trades plummeted to half the previous rate. To get an in-depth look at AMBI, get Portfolio Grader’s complete analysis of AMBI 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.