The ratings of 6 Biotechnology stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

OvaScience, Inc. (OVAS) is having a tough week. The company’s rating falls from a D to a F. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of OVAS stock.

Slipping from a D to a F rating, Aegerion Pharmaceuticals, Inc. (AEGR) takes a hit this week. Aegerion Pharmaceuticals, Inc. is an emerging biopharmaceutical company focused on the development and commercialization of novel therapeutics to treat severe lipid disorders. The company also gets F’s in earnings surprise and return on equity. For more information, get Portfolio Grader’s complete analysis of AEGR stock.

ARCA biopharma, Inc.’s (ABIO) rating weakens this week, dropping to a D versus last week’s C. ARCA biopharma, Inc. is a biopharmaceutical company whose main focus is developing genetically-targeted therapies for heart failure and other cardiovascular diseases. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of ABIO stock.

This week, Biota Pharmaceuticals, Inc.’s (BOTA) rating worsens to a D from the company’s C rating a week ago. Biota Pharmaceuticals, Inc. is an anti-infective drug development company with expertise in respiratory diseases, particularly influenza. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of BOTA stock.

Argos Therapeutics, Inc. (ARGS) declines this week from a D to a F. Argos Therapeutics, Inc. is a biopharmaceutical company focused on the development and commercialization of fully personalized immunotherapies for the treatment of cancer and infectious diseases based on its proprietary technology platform. The company also gets F’s in sales growth and free cash flow. For more information, get Portfolio Grader’s complete analysis of ARGS stock.

Neothetics, Inc. (NEOT) slips from a C to a D this week. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of NEOT 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.