The ratings of four service stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Coinstar (CSTR) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Coinstar is a multi-national company that offers solutions for storefronts, including self-service coin counting, entertainment services, and self-service DVD kiosks. CSTR also rates an F in Portfolio Grader’s specific subcategory of Earnings Momentum. As of Oct. 17, 2013, 34.2% of outstanding Coinstar shares were held short. To get an in-depth look at CSTR, get Portfolio Grader’s complete analysis of CSTR stock.

The rating of American Public Education, Inc. (APEI) slips from a C to a D. American Public Education provides online postsecondary education focusing on the needs of the military and public service communities. For more information, get Portfolio Grader’s complete analysis of APEI stock.

Career Education Corporation (CECO) earns a D this week, moving down from last week’s grade of C. Career Education provides on-ground private, for-profit, postsecondary education in the United States, in addition to having a presence in online education. The stock gets F’s in Equity, Cash Flow and Sales Growth. To get an in-depth look at CECO, get Portfolio Grader’s complete analysis of CECO stock.

Slipping from a C to a D rating, DeVry Education Group Inc. (DV) takes a hit this week. DeVry provides educational services worldwide and operates various institutions of higher education. For more information, get Portfolio Grader’s complete analysis of DV 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.