This week, these ten stocks have the worst year-to-date performance. Each of these also rates an “F” (“strong sell”) on Portfolio Grader.

Since January 1, New Gold Inc. (NGD) has fallen 51.1%. New Gold acquires, explores, and develops gold properties. For more information, get Portfolio Grader’s complete analysis of NGD stock.

Shares of Yamana Gold (AUY) have dipped 51.2% since the first of the year. Yamana Gold is a gold producer with significant gold production, gold development stage properties, exploration properties, and land positions in Brazil, Chile, Argentina, Mexico, and Colombia. For more information, get Portfolio Grader’s complete analysis of AUY stock.

Share prices of Gerdau S.A. Sponsored ADR Pfd (GGB) are down 52.8% since the first of the year. Gerdau is a Brazilian corporation that produces crude steel and related products. Trade volume is up 107.8% from the previous week. For more information, get Portfolio Grader’s complete analysis of GGB stock.

Since the first of the year, 3D Systems Corporation (DDD) has dipped 58.4%. 3D Systems engages in the design, development, manufacture, marketing, and servicing of 3D printers and related products, print materials, and services. As of Aug. 6, 2015, 32.5% of outstanding 3D Systems Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of DDD stock.

Shares of Ocwen Financial Corporation (OCN) have sunk 61.6% since the first of the year. Ocwen Financial is a diversified financial services holding company. As of Aug. 6, 2015, 23.9% of outstanding Ocwen Financial Corporation shares were held short. Shares of the stock have been changing hands at an unusually rapid pace, up 296.7% from the week prior. For more information, get Portfolio Grader’s complete analysis of OCN stock.

Shares of Helix Energy Solutions Group, Inc. (HLX) have fallen 61.8% since January 1. Helix Energy Solutions is a marine contractor and operator of offshore oil and gas properties and production facilities. For more information, get Portfolio Grader’s complete analysis of HLX stock.

Since the first of the year, the price of Cliffs Natural Resources (CLF) is down 62.7%. Cliffs Natural Resources is an international mining and natural resources company. As of Aug. 6, 2015, 42.6% of outstanding Cliffs Natural Resources shares were held short. For more information, get Portfolio Grader’s complete analysis of CLF stock.

Since January 1, Stone Energy Corporation (SGY) has plunged 68.5%. Stone Energy is an independent oil and natural gas company engaged in the acquisition, exploration, exploitation, development and operation of oil and gas properties. As of Aug. 6, 2015, 17.4% of outstanding Stone Energy Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of SGY stock.

Shares of Natural Resource Partners (NRP) have slumped 70% since the first of the year. Natural Resource Partners owns and manages coal properties in Appalachia, the Illinois Basin, and the Western United States. For more information, get Portfolio Grader’s complete analysis of NRP stock.

Shares of Peabody Energy Corporation (BTU) have slipped 86% since January 1. Peabody Energy mines steal, coal, and metallurgical coal to sell to electric utilities and industrial customers. As of Aug. 6, 2015, 35.3% of outstanding Peabody Energy Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of BTU 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.