This week, four commercial services stocks are improving their overall rating on Portfolio Grader. Each of these rates an “A” (“strong buy”) or “B” overall (“buy”).

Republic Services, Inc. (RSG) is making headway this week, with the company’s rating improving to an A (“strong buy”) from a B (“buy”) last week. Republic Services provides non-hazardous solid waste collection services for commercial, industrial, municipal and residential customers. In Portfolio Grader’s specific subcategory of Margin Growth, RSG also gets an A. For more information, get Portfolio Grader’s complete analysis of RSG stock.

This week, Viad Corp (VVI) is showing significant improvement as the company’s rating hops from a C (“hold”) to a B (“buy”). Viad provides high-quality, place-based marketing services in North America, the United Kingdom and the United Arab Emirates, as well as travel and recreation services in the United States and Canada. For more information, get Portfolio Grader’s complete analysis of VVI stock.

Hudson Technologies, Inc. (HDSN) earns a B this week, jumping up from last week’s grade of C. Hudson Technologies sells refrigerants, as well as provides a variety of related services. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of HDSN stock.

This is a strong week for Waste Management, Inc. (WM). The company’s rating climbs to A from the previous week’s B. Waste Management provides collection, transfer, recycling, disposal and waste-to-energy services. For more information, get Portfolio Grader’s complete analysis of WM 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.