The ratings of three metals and mining stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

North American Palladium (PAL) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). North American Palladium is a mineral exploration and production company. In Portfolio Grader’s specific subcategories of Earnings Revisions, Equity and Cash Flow, PAL also gets an F. For more information, get Portfolio Grader’s complete analysis of PAL stock.

Keegan Resources (KGN) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Keegan Resources, a junior gold company, engages in the exploration and development of gold properties in Ghana, west Africa. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at KGN, get Portfolio Grader’s complete analysis of KGN stock.

Slipping from a C to a D rating, Hecla Mining Company (HL) takes a hit this week. Hecla Mining explores, develops, and mines precious metals, gold, and silver. The stock also gets an F in Earnings Revisions. For more information, get Portfolio Grader’s complete analysis of HL 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.