This week, the ratings of 5 Life Sciences Tools & Services stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Illumina, Inc. (ILMN) slips from a C to a D this week. Illumina, Inc. develops, manufactures and markets integrated systems for the large-scale analysis of genetic variation and biological function. For more information, get Portfolio Grader’s complete analysis of ILMN stock.

This week, PerkinElmer, Inc. (PKI) drops from a C to a D rating. PerkinElmer, Inc. provides technology, services and solutions to the diagnostics, research, environmental, industrial and laboratory services market. For more information, get Portfolio Grader’s complete analysis of PKI stock.

QIAGEN NV (QGEN) gets weaker ratings this week as last week’s C drops to a D. QIAGEN NV provides sample and assay technologies. For more information, get Portfolio Grader’s complete analysis of QGEN stock.

Pacific Biosciences of California, Inc. (PACB) experiences a ratings drop this week, going from last week’s C to a D. Pacific Biosciences of California, Inc. has developed a novel approach to studying the synthesis and regulation of DNA, RNA and protein. 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 PACB stock.

Compugen Ltd. (CGEN) is having a tough week. The company’s rating falls from a C to a D. Compugen Ltd. focuses on the therapeutic proteins and monoclonal antibodies to address unmet needs in the fields of immunology and oncology. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of CGEN 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.