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

MagnaChip Semiconductor Corporation (MX) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). Magnachip Semiconductor designs, develops, and manufactures mixed-signal and digital multimedia semiconductors. In Portfolio Grader’s specific subcategories of Earnings Growth, Earnings Revisions, Equity, Cash Flow and Margin Growth, MX also gets F’s. To get an in-depth look at MX, get Portfolio Grader’s complete analysis of MX stock.

This week, NeoPhotonics Corporation’s (NPTN) rating worsens to an F from the company’s D rating a week ago. NeoPhotonics designs, manufacturers, and markets standard and semi custom planar light wave circuits for metro access and other advanced optical communications platforms. The stock gets F’s in Equity and Cash Flow. For more information, get Portfolio Grader’s complete analysis of NPTN stock.

Advanced Energy Industries, Inc. (AEIS) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Advanced Energy Industries are engaged in the design, manufacturing, sale and support of industrial power conversion products that transform power into various usable forms. The stock also gets an F in Earnings Momentum. To get an in-depth look at AEIS, get Portfolio Grader’s complete analysis of AEIS stock.

This week, JinkoSolar Holding Co., Ltd. Sponsored ADR (JKS) drops from a C to a D rating. JinkoSolar Holding produces silicon wafers, solar cells, and solar modules. The stock also rates an F in Earnings Momentum. As of April 1, 2015, 12.2% of outstanding JinkoSolar Holding Co., Ltd. Sponsored ADR shares were held short. For more information, get Portfolio Grader’s complete analysis of JKS stock.

This is a rough week for Power Integrations, Inc. (POWI). The company’s rating falls to D from the previous week’s C. Power Integrations designs, develops, and markets analog integrated circuits for use in alternating current to direct current power conversion. The stock also gets an F in Sales Growth. The stock currently has a trailing PE Ratio of 27.40. To get an in-depth look at POWI, get Portfolio Grader’s complete analysis of POWI stock.

Ultra Clean Holdings, Inc. (UCTT) earns a D this week, falling from last week’s grade of C. Ultra Clean Holdings is a developer and supplier of critical subsystems, mainly for the semiconductor capital equipment industry. The stock gets F’s in Earnings Growth, Earnings Momentum and Earnings Revisions. For more information, get Portfolio Grader’s complete analysis of UCTT 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.