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) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. 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 week, TeleNav Inc. (NASDAQ:TNAV) drops from a C to a D rating. 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.

Red Hat (NYSE:RHT) gets weaker ratings this week as last week’s C drops to a D. Red Hat provides open source software solutions that customers are allowed to update, monitor and manage. The trailing PE Ratio for the stock is 60.00. For more information, get Portfolio Grader’s complete analysis of RHT stock.

This is a rough week for Taomee Holdings (NYSE:TAOM). The company’s rating falls to D from the previous week’s C. 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.