This week, the ratings of 12 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 (YOKU) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). Youku Tudou is an Internet television company. To get an in-depth look at YOKU, get Portfolio Grader’s complete analysis of YOKU stock.

Marchex, Inc. Class B (MCHX) gets weaker ratings this week as last week’s D drops to an F. Marchex offers call-based advertising and related services, pay-per-click advertising and related services and proprietary traffic sources. The stock receives F’s in Earnings Growth, Earnings Momentum and Earnings Surprise. Equity and Cash Flow also get F’s. Shares of the stock are changing hands at twice the rate they were a week ago. For more information, get Portfolio Grader’s complete analysis of MCHX stock.

Unwired Planet, Inc.’s (UPIP) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Unwired Planet develops patents that allow mobile devices to connect to the Internet. The stock gets F’s in Earnings Revisions and Equity. Shares of the stock have been trading at an exceptionally rapid pace, up threefold from the week prior. To get an in-depth look at UPIP, get Portfolio Grader’s complete analysis of UPIP stock.

ChinaCache International Holdings Ltd. Sponsored ADR (CCIH) is having a tough week. The company’s rating falls from a C to a D. ChinaCache International provides a portfolio of services and solutions to businesses, government agencies and other enterprises to enhance the reliability and scalability of their online services and applications and improve end-user experience. For more information, get Portfolio Grader’s complete analysis of CCIH stock.

This week, E2open, Inc. (EOPN) drops from a D to an F rating. E2open develops and deploys enterprise software cloud solutions for businesses. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at EOPN, get Portfolio Grader’s complete analysis of EOPN stock.

iPass (IPAS) earns an F this week, moving down from last week’s grade of 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 receives F’s in Earnings Revisions, Equity, Cash Flow and Sales Growth. For more information, get Portfolio Grader’s complete analysis of IPAS stock.

Slipping from a D to an F rating, Velti (VELT) takes a hit this week. Velti is a global provider of mobile marketing and advertising solutions. The stock gets F’s in Earnings Growth and Earnings Momentum. To get an in-depth look at VELT, get Portfolio Grader’s complete analysis of VELT stock.

Travelzoo (TZOO) gets weaker ratings this week as last week’s D drops to an F. Travelzoo is an Internet media company that publishes travel and entertainment deals from travel and entertainment companies, and local businesses in North America, Europe, and the Asia Pacific. The stock gets F’s in Earnings Growth, Earnings Revisions and Sales Growth. Shares of the stock have been changing hands at an unusually rapid pace, up 1143.5% from the week prior. For more information, get Portfolio Grader’s complete analysis of TZOO stock.

Homeaway, Inc.’s (AWAY) rating weakens this week, dropping to an F versus last week’s D. HomeAway operates an online marketplace for the vacation rental industry worldwide, and offers homes, condominiums, villas, and cabins to the public on a nightly, weekly, or monthly basis. The stock gets F’s in Earnings Growth and Margin Growth. The stock’s trailing PE Ratio is 449.60. To get an in-depth look at AWAY, get Portfolio Grader’s complete analysis of AWAY stock.

This week, CoStar Group, Inc. (CSGP) drops from a C to a D rating. CoStar provides information and analytic services to the commercial real estate industry in the United States, the United Kingdom, and France. The stock also rates an F in Earnings Momentum. The stock currently has a trailing PE Ratio of 226.20. For more information, get Portfolio Grader’s complete analysis of CSGP stock.

Slipping from a C to a D rating, Leju Holdings Ltd. Sponsored ADR (LEJU) takes a hit this week. The stock gets F’s in Earnings Growth and Earnings Revisions. To get an in-depth look at LEJU, get Portfolio Grader’s complete analysis of LEJU stock.

The rating of Xunlei Ltd. ADR (XNET) slips from a C to a D. The stock also gets an F in Earnings Surprise. For more information, get Portfolio Grader’s complete analysis of XNET 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.