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. For Portfolio Grader’s specific subcategory of Earnings Momentum, CSTR also gets an F. As of Oct. 17, 2013, 34.2% of outstanding Coinstar shares were held short. For more information, get Portfolio Grader’s complete analysis of CSTR stock.

American Public Education, Inc. (APEI) gets weaker ratings this week as last week’s C drops to a D. American Public Education provides online postsecondary education focusing on the needs of the military and public service communities. To get an in-depth look at APEI, get Portfolio Grader’s complete analysis of APEI stock.

Slipping from a C to a D rating, Career Education Corporation (CECO) takes a hit this week. 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. For more information, get Portfolio Grader’s complete analysis of CECO stock.

This is a rough week for DeVry Education Group Inc. (DV). The company’s rating falls to D from the previous week’s C. DeVry provides educational services worldwide and operates various institutions of higher education. To get an in-depth look at DV, 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.