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

Workday, Inc. Class A’s (WDAY) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Workday provides software-as-a-service solutions for managing global businesses, combining a lower cost of ownership with an innovative approach to business applications. In Portfolio Grader’s specific subcategory of Equity, WDAY also gets an F. To get an in-depth look at WDAY, get Portfolio Grader’s complete analysis of WDAY stock.

This is a rough week for SRS Labs (SRSL). The company’s rating falls to D from the previous week’s C. SRS Labs develops and licenses audio and voice enhancement technologies. The stock gets F’s in Earnings Growth and Margin Growth. For more information, get Portfolio Grader’s complete analysis of SRSL stock.

Taomee Holdings Ltd. Sponsored ADR (TAOM) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Taomee Holdings produces children’s entertainment. The stock receives F’s in Earnings Growth, Earnings Momentum and Earnings Revisions. Margin Growth and Sales Growth also get F’s. The stock currently has a trailing PE Ratio of 165.50. To get an in-depth look at TAOM, get Portfolio Grader’s complete analysis of TAOM stock.

Mavenir Systems, Inc. (MVNR) earns a D this week, moving down from last week’s grade of C. The stock gets F’s in Earnings Revisions and Equity. For more information, get Portfolio Grader’s complete analysis of MVNR stock.

Zix Corporation (ZIXI) is having a tough week. The company’s rating falls from a C to a D. Zix provides secure, Internet-based applications in a Software-as-a-Service (SaaS) model. The stock gets F’s in Earnings Growth, Earnings Momentum and Earnings Surprise. The stock’s trailing PE Ratio is 62.30. To get an in-depth look at ZIXI, get Portfolio Grader’s complete analysis of ZIXI stock.

Slipping from a C to a D rating, Digimarc Corporation (DMRC) takes a hit this week. Digimarc provides media identification and management solutions to commercial entities and government customers in the United States and internationally. The stock gets F’s in Earnings Momentum, Earnings Revisions and Equity. Margin Growth and Sales Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of DMRC 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.