This week, the overall grades of four Software stocks are lower, 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. For more information, 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. The stock price has dropped 7.5% over the past month, worse than the 1.3% decrease the Nasdaq has seen over the same period of time. To get an in-depth look at TNAV, get Portfolio Grader’s complete analysis of TNAV stock.

This week, Red Hat, Inc.’s (NYSE:RHT) rating worsens to a D from the company’s C rating a week ago. Red Hat provides open source software solutions that customers are allowed to update, monitor and manage. The trailing PE Ratio for the stock is 63.50. For a full analysis of RHT stock, visit Portfolio Grader.

Taomee Holdings Ltd. Sponsored ADR’s (NYSE:TAOM) rating weakens this week, dropping to a D versus last week’s C. 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 9% over the past month. To get an in-depth look at TAOM, 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.