This week, the ratings of six Internet and Web Service stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Youku Tudou, Inc. Sponsored ADR Class A (NYSE:YOKU) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Youku.com operates as an Internet television company in the People’s Republic of China. In Portfolio Grader’s specific subcategories of Earnings Revisions and Equity, YOKU also gets F’s. To get an in-depth look at YOKU, get Portfolio Grader’s complete analysis of YOKU stock.

The rating of E2open, Inc. (NASDAQ:EOPN) declines this week from a C to a D. The stock price has fallen 19.1% over the past month, worse than the 1.3% decrease the Nasdaq has seen over the same period of time. For a full analysis of EOPN stock, visit Portfolio Grader.

21Vianet Group, Inc. Sponsored ADR Class A (NASDAQ:VNET) earns a D this week, moving down from last week’s grade of C. 21Vianet Group provides carrier-neutral Internet data center services in the People’s Republic of China. The stock gets F’s in Earnings Growth and Earnings Momentum. The stock currently has a trailing PE Ratio of 666.10. For more information, get Portfolio Grader’s complete analysis of VNET stock.

iPass (NASDAQ:IPAS) experiences a ratings drop this week, going from last week’s C to a D. iPass offers enterprise mobility services on a global basis by providing services that simply, smartly and openly facilitate network access from mobile devices while providing the enterprise with visibility and control over their mobile ecosystem. The stock gets F’s in Earnings Revisions, Equity, and Sales Growth. To get an in-depth look at IPAS, get Portfolio Grader’s complete analysis of IPAS stock.

Slipping from a C to a D rating, Liquidity Services, Inc. (NASDAQ:LQDT) takes a hit this week. Liquidity Services provides full service solutions to market and sell surplus assets and wholesale goods. The stock also gets an F in Earnings Momentum. As of Oct. 18, 2013, 29.8% of outstanding Liquidity Services, Inc. shares were held short. The trailing PE Ratio for the stock is 28.10. For a full analysis of LQDT stock, visit Portfolio Grader.

Velti (NASDAQ:VELT) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). Velti is a global provider of mobile marketing and advertising solutions. The stock gets F’s in Earnings Growth and Earnings Momentum. As of Oct. 18, 2013, 17.2% of outstanding Velti shares were held short. For more information, get Portfolio Grader’s complete analysis of VELT 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.