This week, 8 Software stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

NetSuite Inc. (N) experiences a ratings drop this week, going from last week’s C to a D. NetSuite Inc. provides relationship management software solutions. The company also gets F’s in return on equity. For more information, get Portfolio Grader’s complete analysis of N stock.

This is a rough week for SS&C; Technologies Holdings, Inc. (SSNC). The company’s rating falls to D from the previous week’s C. SS&C; Technologies Holdings, Inc. develops and markets computer software for financial services providers. 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 SSNC stock.

This week, Aspen Technology, Inc.’s (AZPN) rating worsens to a D from the company’s C rating a week ago. Aspen Technology, Inc. is a global provider of mission-critical process optimization software solutions, which are designed to manage and optimize plant and process design, operational performance, and supply chain planning. For more information, get Portfolio Grader’s complete analysis of AZPN stock.

Qualys, Inc. (QLYS) declines this week from a C to a D. The company also gets F’s in earnings momentum. For more information, get Portfolio Grader’s complete analysis of QLYS stock.

Guidance Software, Inc.’s (GUID) rating weakens this week, dropping to a D versus last week’s C. Guidance Software, Inc. develops and produces software solutions for digital investigations. The company also gets F’s in earnings revisions and return on equity. For more information, get Portfolio Grader’s complete analysis of GUID stock.

Zix Corporation (ZIXI) slips from a C to a D this week. Zix Corporation provides secure, Internet-based applications in a Software-as-a-Service (SaaS) model. For more information, get Portfolio Grader’s complete analysis of ZIXI stock.

Zynga Inc. Class A (ZNGA) is having a tough week. The company’s rating falls from a C to a D. Zynga Inc. Class A develops, markets, and operates online social games as live services played over the Internet and on social networking sites and mobile platforms. For more information, get Portfolio Grader’s complete analysis of ZNGA stock.

Covisint Corp. (COVS) earns a D this week, moving down from last week’s grade of C. The company also gets F’s in sales growth and return on equity. For more information, get Portfolio Grader’s complete analysis of COVS 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.