This week, the overall grades of 3 Metals & Mining stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Allegheny Technologies Incorporated (ATI) drops from a D to a F rating. Allegheny Technologies Incorporated produces specialty metals such as titanium alloys and superalloys. The company also gets F’s in sales growth, earnings growth, earnings revisions, earnings surprise, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of ATI stock.

Vale S.A. Sponsored ADR (VALE) experiences a ratings drop this week, going from last week’s C to a D. Vale S.A. Sponsored ADR is a Brazil-based metals and mining company that engages in the exploration, production and sale of basic metals. The company also gets F’s in sales growth, operating margin growth, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of VALE stock.

Slipping from a C to a D rating, Gerdau S.A. Sponsored ADR Pfd (GGB) takes a hit this week. Gerdau S.A. Sponsored ADR Pfd is a Brazilian corporation that produces crude steel and related products. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of GGB 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.