This week, the overall grades of 4 Biotechnology stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

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 momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of CFRX stock.

Kindred Biosciences, Inc. (KIN) gets weaker ratings this week as last week’s D drops to a F. 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.

BioCryst Pharmaceuticals, Inc. (BCRX) slips from a C to a D this week. BioCryst Pharmaceuticals, Inc. is a biotechnology company that designs, optimizes and develops novel drugs that block key enzymes involved in cancer, viral infections and autoimmune diseases. 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 BCRX stock.

MannKind Corporation’s (MNKD) rating weakens this week, dropping to a D versus last week’s C. MannKind Corporation is a biopharmaceutical company focused on the development and commercialization of therapeutic products for diseases such as diabetes, cancer, inflammatory and autoimmune diseases. The company also gets F’s in earnings momentum and free cash flow. For more information, get Portfolio Grader’s complete analysis of MNKD 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.