The overall ratings of 3 Metals & Mining stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Materion Corporation’s (MTRN) rating worsens to a D from the company’s C rating a week ago. Materion Corporation produces and supplies high-performance engineered materials. For more information, get Portfolio Grader’s complete analysis of MTRN stock.

Teck Resources Limited Class B (TCK) gets weaker ratings this week as last week’s D drops to a F. Teck Resources Limited Class B engages in exploring for, acquiring, developing, and producing natural resources in the Americas, Asia Pacific, Europe, and Africa. 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 TCK stock.

Slipping from a D to a F rating, AK Steel Holding Corporation (AKS) takes a hit this week. AK Steel Holding Corporation produces flat-rolled carbon, stainless and electrical steels, and tubular products in the United States and internationally. The company also gets F’s in earnings momentum and free cash flow. For more information, get Portfolio Grader’s complete analysis of AKS 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.