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”).

Coinstar (CSTR) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. 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. To get an in-depth look at CSTR, get Portfolio Grader’s complete analysis of CSTR stock.

This week, American Public Education, Inc. (APEI) drops from a C to a D rating. 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.

The rating of Career Education Corporation (CECO) slips from a C to a D. 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.

DeVry Education Group Inc. (DV) is having a tough week. The company’s rating falls from a C to a D. 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.