This week, the ratings of 5 Biotechnology stocks on Portfolio Grader are down. 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 C to a D. 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, earnings growth, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of ALXN stock.

Medivation, Inc. (MDVN) declines this week from a C to a D. Medivation, Inc. acquires, develops, and sells or partners biomedical technologies in the early development stage of the research and development process. The company also gets F’s in earnings momentum. For more information, get Portfolio Grader’s complete analysis of MDVN stock.

OvaScience, Inc.’s (OVAS) rating weakens this week, dropping to a D versus last 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 OVAS stock.

PDL BioPharma, Inc. (PDLI) gets weaker ratings this week as last week’s D drops 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 surprise. For more information, get Portfolio Grader’s complete analysis of PDLI stock.

Eleven Biotherapeutics, Inc. (EBIO) is having a tough week. The company’s rating falls from a C to a D. 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 EBIO 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.