The ratings of four Software stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, SRS Labs (NASDAQ:SRSL) falls to a D (“sell”), worse than last week’s grade of C (“hold”). SRS Labs develops and licenses audio and voice enhancement technologies. In Portfolio Grader’s specific subcategories of Earnings Growth and Margin Growth, SRSL also gets F’s. To get an in-depth look at SRSL, get Portfolio Grader’s complete analysis of SRSL stock.

This is a rough week for TeleNav Inc. (NASDAQ:TNAV). The company’s rating falls to D from the previous week’s C. TeleNav provides location-based solutions. The stock gets F’s in Earnings Growth, Earnings Momentum, and Margin Growth. For a full analysis of TNAV stock, visit Portfolio Grader.

The rating of Red Hat (NYSE:RHT) declines this week from a C to a D. Red Hat provides open source software solutions that customers are allowed to update, monitor and manage. The stock has a trailing PE Ratio of 64.30. For more information, get Portfolio Grader’s complete analysis of RHT stock.

Slipping from a C to a D rating, Taomee Holdings (NYSE:TAOM) takes a hit this week. Taomee Holdings produces children’s entertainment. The stock gets F’s in Earnings Surprise and Margin Growth. For a full analysis of TAOM stock, visit Portfolio Grader.

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.