This week, the ratings of four Software stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Taomee Holdings (NYSE:TAOM) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Taomee Holdings produces children’s entertainment. In Portfolio Grader’s specific subcategories of Earnings Surprise and Margin Growth, TAOM also gets F’s. The stock price has fallen 17.7% over the past month, worse than the 2.3% increase the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of TAOM stock.

The rating of SRS Labs (NASDAQ:SRSL) slips from C to a D. SRS Labs develops and licenses audio and voice enhancement technologies. The stock gets F’s in Earnings Growth and Margin Growth. To get an in-depth look at SRSL, get Portfolio Grader’s complete analysis of SRSL stock.

TeleNav Inc. (NASDAQ:TNAV) earns a D this week, moving down from last week’s grade of C. TeleNav provides location-based solutions. The stock gets F’s in Earnings Growth, Earnings Momentum, and Margin Growth. The stock price has fallen 15.1% over the past month. For a full analysis of TNAV stock, visit Portfolio Grader.

Red Hat (NYSE:RHT) experiences a ratings drop this week, going from last week’s C to a D. Red Hat provides open source software solutions that customers are allowed to update, monitor and manage. Share prices fell 7.2% over the past month. The stock’s trailing PE Ratio is 66.70. For more information, get Portfolio Grader’s complete analysis of RHT 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.