The overall ratings of 23 Biotechnology stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Alexion Pharmaceuticals, Inc. (ALXN) experiences a ratings drop this week, going from last week’s D to a F. 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. For more information, get Portfolio Grader’s complete analysis of ALXN stock.

Alkermes Plc (ALKS) gets weaker ratings this week as last week’s C drops to a D. Alkermes Plc is a fully integrated biotechnology company committed to developing medicines that will improve patients’ lives. The company also gets F’s in return on equity. For more information, get Portfolio Grader’s complete analysis of ALKS stock.

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

Slipping from a D to a F rating, La Jolla Pharmaceutical Company (LJPC) 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 LJPC stock.

Eiger BioPharmaceuticals, Inc. (EIGR) 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 and earnings surprise. For more information, get Portfolio Grader’s complete analysis of EIGR stock.

This week, Dynavax Technologies Corporation (DVAX) drops from a D to a F rating. 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 return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of DVAX stock.

Enzymotec Ltd. (ENZY) declines this week from a D to a F. The company also gets F’s in sales growth, earnings growth, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of ENZY stock.

This is a rough week for Trevena, Inc. (TRVN). The company’s rating falls to D from the previous week’s B. The company also gets F’s in earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of TRVN stock.

This week, Ignyta, Inc.’s (RXDX) rating worsens to a F from the company’s D 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 RXDX stock.

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

VBI Vaccines, Inc.’s (VBIV) rating weakens this week, dropping to a F versus last week’s D. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of VBIV stock.

Calithera Biosciences, Inc. (CALA) 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 CALA stock.

This week, BioTime, Inc. (BTX) drops from a C to a D rating. BioTime, Inc. is a biotechnology company that focuses on regenerative medicine and blood plasma volume expanders. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of BTX stock.

Slipping from a C to a D rating, Ohr Pharmaceutical, Inc. (OHRP) takes a hit this week. Ohr Pharmaceutical, Inc. develops pharmaceuticals for wound care and to treat cachexia. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of OHRP stock.

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

Lpath, Inc. (LPTN) gets weaker ratings this week as last week’s C drops to a D. Lpath, Inc. is a drug discovery company with a focus on bioactive signaling lipids as targets for treating and diagnosing human diseases. 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 LPTN stock.

Tenax Therapeutics, Inc. (TENX) earns a F this week, moving down from last week’s grade of 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 TENX stock.

Tonix Pharmaceuticals Holding Corp. (TNXP) 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 TNXP stock.

This week, Cytori Therapeutics, Inc.’s (CYTX) rating worsens to a F from the company’s D rating a week ago. Cytori Therapeutics, Inc. develops, manufactures and sells medical products to enable the practice of regenerative medicine. The company also gets F’s in sales growth, earnings growth, earnings surprise, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of CYTX stock.

Cleveland BioLabs, Inc.’s (CBLI) rating weakens this week, dropping to a F versus last week’s D. Cleveland BioLabs, Inc. is a drug discovery and development company leveraging its proprietary discoveries around programmed cell death to develop treatments for cancer and protection of normal tissues from radiation and other stresses. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of CBLI stock.

AmpliPhi BioSciences Corporation (APHB) declines this week from a D to a F. The company also gets F’s in operating margin growth, earnings growth, earnings revisions, earnings surprise, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of APHB 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 return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of ARNA stock.

Catalyst Pharmaceuticals, Inc. (CPRX) gets weaker ratings this week as last week’s D drops 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 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.