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”).

SRS Labs (NASDAQ:SRSL) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. 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. For a full analysis of SRSL stock, visit Portfolio Grader.

The rating of TeleNav Inc. (NASDAQ:TNAV) declines this week from a C to a D. TeleNav provides location-based solutions. The stock gets F’s in Earnings Growth, Earnings Momentum, and Margin Growth. For more information, get Portfolio Grader’s complete analysis of TNAV stock.

Red Hat’s (NYSE:RHT) rating weakens this week, dropping to a D versus last week’s C. Red Hat provides open source software solutions that customers are allowed to update, monitor and manage. The stock price has dropped 9.1% over the past month, worse than the 1% decrease the S&P 500 has seen over the same period of time. The stock has a trailing PE Ratio of 64.50. To get an in-depth look at RHT, get Portfolio Grader’s complete analysis of RHT stock.

Taomee Holdings (NYSE:TAOM) experiences a ratings drop this week, going from last week’s C to a D. Taomee Holdings produces children’s entertainment. The stock gets F’s in Earnings Surprise and Margin Growth. Wall Street appears to agree with the stock downgrade, with share prices dropping 17.9% over the past month. For more information, get Portfolio Grader’s complete analysis of TAOM 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.