This week, 6 Biotechnology stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Osiris Therapeutics, Inc. (OSIR) experiences a ratings drop this week, going from last week’s C to a D. Osiris Therapeutics, Inc. researches and develops therapeutic products for the regeneration of human connective tissues. The company also gets F’s in earnings growth, earnings revisions, and earnings surprise. For more information, get Portfolio Grader’s complete analysis of OSIR stock.

This week, Kindred Biosciences, Inc. (KIN) drops from a D to a F rating. The company also gets F’s in earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of KIN stock.

GlobeImmune, Inc. (GBIM) declines this week from a C to a D. The company also gets F’s in sales growth, operating margin growth, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of GBIM stock.

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

Orexigen Therapeutics, Inc.’s (OREX) rating weakens this week, dropping to a F versus last week’s D. Orexigen Therapeutics, Inc. is focused on the development and commercialization of pharmaceutical products for the treatment of the central nervous system disorders with an initial focus on obesity. The company also gets F’s in sales growth, earnings growth, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of OREX stock.

XOMA Corporation (XOMA) gets weaker ratings this week as last week’s C drops to a D. XOMA Corporation engages in the discovery and development of antibody-based therapeutics in the United States, Europe, and the Asia Pacific. The company also gets F’s in sales growth and free cash flow. For more information, get Portfolio Grader’s complete analysis of XOMA 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.