This week, the ratings of 19 Biotechnology stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Slipping from a C to a D rating, Repligen Corporation (RGEN) takes a hit this week. Repligen Corporation is a biopharmaceutical company that develops therapeutics for radiology and neuropsychiatry. For more information, get Portfolio Grader’s complete analysis of RGEN stock.

Intrexon Corporation’s (XON) rating weakens this week, dropping to a D versus last week’s C. The company also gets F’s in earnings growth, earnings revisions, earnings surprise, earnings momentum, and return on equity. For more information, get Portfolio Grader’s complete analysis of XON stock.

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

Cellular Biomedicine Group, Inc. (CBMG) 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 CBMG stock.

Dynavax Technologies Corporation (DVAX) slips from a C to a D this week. Dynavax Technologies Corporation discovers and develops novel products to prevent and treat infectious diseases, asthma and inflammatory and autoimmune diseases. 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 DVAX stock.

Cidara Therapeutics, Inc. (CDTX) experiences a ratings drop this week, going from last week’s C to a D. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of CDTX stock.

This week, MiMedx Group, Inc. (MDXG) drops from a C to a D rating. MiMedx Group, Inc. operates as a medical device company. The company also gets F’s in earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of MDXG stock.

This week, Pfenex, Inc.’s (PFNX) rating worsens to a D from the company’s C rating a week ago. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of PFNX stock.

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

Keryx Biopharmaceuticals, Inc. (KERX) gets weaker ratings this week as last week’s C drops to a D. Keryx Biopharmaceuticals, Inc. focuses on developing and commercializing pharmaceuticals for the treatment of cancer and renal disease. The company also gets F’s in earnings revisions, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of KERX stock.

VBI Vaccines, Inc. (VBIV) declines this week from a C to a F. The company also gets F’s in return on equity. For more information, get Portfolio Grader’s complete analysis of VBIV stock.

PDL BioPharma, Inc. (PDLI) is having a tough week. The company’s rating falls from a D to a F. PDL BioPharma, Inc. engages in intellectual property asset management and patent portfolio and related assets investment activities. The company also gets F’s in earnings revisions and earnings surprise. For more information, get Portfolio Grader’s complete analysis of PDLI stock.

This week, Geron Corporation’s (GERN) rating worsens to a D from the company’s C rating a week ago. Geron Corporation is a biopharmaceutical company that discovers and develops therapeutic and diagnostic products to treat cancer and other age-related degenerative diseases including spinal cord injury, heart failure and diabetes. For more information, get Portfolio Grader’s complete analysis of GERN stock.

CytRx Corporation (CYTR) slips from a C to a D this week. CytRx Corporation is a biopharmaceutical research and development company that specializes in 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 CYTR stock.

ContraFect Corp. (CFRX) experiences a ratings drop this week, going from last week’s C to a D. The company also gets F’s in earnings revisions, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of CFRX stock.

Pieris Pharmaceuticals, Inc.’s (PIRS) rating weakens this week, dropping to a D versus last week’s C. 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 PIRS stock.

Slipping from a C to a D rating, Pluristem Therapeutics Inc. (PSTI) takes a hit this week. Pluristem Therapeutics Inc. develops Messenchymal stem cell production technology and commercializes cell therapy products. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of PSTI stock.

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

Oncothyreon Inc. (ONTY) gets weaker ratings this week as last week’s C drops to a D. Oncothyreon Inc. is a biotechnology company that develops therapeutic approaches to cancer management. The company also gets F’s in earnings revisions, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of ONTY 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.