This week, the ratings of three Machinery stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Tennant (NYSE:TNC) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Tennant designs, manufactures and sells of products used mainly in the maintenance of non-residential surfaces. TNC also rates an F in Portfolio Grader’s specific subcategory of Earnings Surprise. Shares of the stock have been changing hands at an unusually rapid pace, three times the rate of the week prior. For a full analysis of TNC stock, visit Portfolio Grader.

This week, Energy Recovery (NASDAQ:ERII) drops from a C to a D rating. Energy Recovery develops and manufactures energy recovery devices utilized in the water desalination industry. The stock gets F’s in Equity, Cash Flow, and Sales Growth. Shares of the stock have been exchanging at an usually rapid pace, twice the rate of the week prior.

For more information, get Portfolio Grader’s complete analysis of ERII stock.

Sauer-Danfoss (NYSE:SHS) experiences a ratings drop this week, going from last week’s C to a D. Sauer-Danfoss designs, manufactures, and markets hydraulic, electronic, and mechanical components, as well as software and integrated systems that generate, transmit, and control power in mobile equipment. The stock also rates an F in Earnings Momentum. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. For a full analysis of SHS stock, visit Portfolio Grader.

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.