This week, 25 Biotechnology stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Slipping from a C to a D rating, Alexion Pharmaceuticals, Inc. (ALXN) takes a hit this week. Alexion Pharmaceuticals, Inc. engages in the innovation, development, and commercialization of life-transforming therapeutic products for treating patients with severe and ultra-rare disorders in the United States, Europe, Latin America, Japan, and the Asia Pacific. The company also gets F’s in operating margin growth and earnings momentum. For more information, get Portfolio Grader’s complete analysis of ALXN stock.

Alnylam Pharmaceuticals, Inc (ALNY) gets weaker ratings this week as last week’s C drops to a D. Alnylam Pharmaceuticals, Inc engages in discovering, developing, and commercializing novel therapeutics based on RNA interference (RNAi). The company also gets F’s in sales growth, earnings momentum, and return on equity. For more information, get Portfolio Grader’s complete analysis of ALNY stock.

bluebird bio, Inc. (BLUE) earns a D this week, moving down from last week’s grade of C. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of BLUE stock.

This is a rough week for Newlink Genetics Corporation (NLNK). The company’s rating falls to D from the previous week’s C. Newlink Genetics Corporation is a biopharmaceutical company focused on discovering, developing, and commercializing novel immunotherapeutic products to improve cancer treatment options for patients and physicians. The company also gets F’s in earnings surprise and earnings momentum. For more information, get Portfolio Grader’s complete analysis of NLNK stock.

Alder Biopharmaceuticals, Inc. (ALDR) experiences a ratings drop this week, going from last week’s C to a D. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, earnings momentum, and return on equity. For more information, get Portfolio Grader’s complete analysis of ALDR stock.

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

This week, Forward Pharma A/S Sponsored ADR (FWP) drops from a C to a D rating. The company also gets F’s in earnings surprise and return on equity. For more information, get Portfolio Grader’s complete analysis of FWP stock.

This week, Insmed Incorporated’s (INSM) rating worsens to a D from the company’s C rating a week ago. Insmed Incorporated develops and commercializes drugs that treat metabolic diseases, endocrine disorders and oncology. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of INSM stock.

Momenta Pharmaceuticals, Inc. (MNTA) declines this week from a C to a D. Momenta Pharmaceuticals, Inc. is a biotechnology company which specializes in sequencing and engineering of complex sugars for the development of improved versions of existing drugs, the development of novel drugs, and the discovery of new biological processes. The company also gets F’s in earnings revisions and return on equity. For more information, get Portfolio Grader’s complete analysis of MNTA stock.

PTC Therapeutics, Inc. (PTCT) slips from a C to a F 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 PTCT stock.

Pfenex Inc’s (PFNX) rating weakens this week, dropping to a D versus last week’s C. The company also gets F’s in sales growth, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of PFNX stock.

Osiris Therapeutics, Inc. (OSIR) is having a tough week. The company’s rating falls from a D to a F. Osiris Therapeutics, Inc. researches and develops therapeutic products for the regeneration of human connective tissues. The company also gets F’s in earnings growth and earnings surprise. For more information, get Portfolio Grader’s complete analysis of OSIR stock.

Sorrento Therapeutics, Inc. (SRNE) earns a D this week, moving down from last week’s grade of C. The company also gets F’s in sales growth, earnings revisions, earnings surprise, and return on equity. For more information, get Portfolio Grader’s complete analysis of SRNE stock.

Cara Therapeutics Inc’s (CARA) rating weakens this week, dropping to a D versus last week’s C. 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 CARA stock.

This is a rough week for GlycoMimetics, Inc. (GLYC). The company’s rating falls to D from the previous week’s C. The company also gets F’s in return on equity. For more information, get Portfolio Grader’s complete analysis of GLYC stock.

Chimerix, Inc. (CMRX) experiences a ratings drop this week, going from last week’s 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 CMRX stock.

This week, Novavax, Inc.’s (NVAX) rating worsens to a D from the company’s C rating a week ago. Novavax, Inc. creates novel vaccines to address a broad range of infectious diseases worldwide using proprietary virus-like particle technology. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of NVAX stock.

Argos Therapeutics, Inc. (ARGS) declines this week from a C to a D. 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.

Slipping from a D to a F rating, Histogenics Corp. (HSGX) takes a hit 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 HSGX stock.

Cerulean Pharma, Inc. (CERU) gets weaker ratings this week as last week’s D drops 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 CERU stock.

This week, CorMedix Inc. (CRMD) drops from a C to a D rating. CorMedix Inc. is a development-stage pharmaceutical company that seeks to fulfill selected, significant unmet medical needs in the therapeutic areas at the crossroads of cardiac and kidney (renal) disease. 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 CRMD stock.

Arena Pharmaceuticals, Inc. (ARNA) slips from a D to a F this week. Arena Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company that develops innovative therapies offering medical advances and new options for patients. 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 ARNA stock.

Biocept, Inc.’s (BIOC) rating weakens this week, dropping to a D versus last week’s B. Biocept, Inc. is a global provider of clinical trials services, providing medical image management and eClinical services, including electronic data capture and clinical data management solutions. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of BIOC stock.

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

Catalyst Pharmaceuticals, Inc. (CPRX) experiences a ratings drop this week, going from last week’s D to a F. Catalyst Pharmaceuticals, Inc. focuses on the development and commercialization of prescription drugs targeting diseases of the central nervous system with a focus on the treatment of drug addiction and epilepsy. 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 CPRX 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.