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 the first of the year, New Gold Inc. (NGD) has tumbled 55.6%. New Gold acquires, explores, and develops gold properties. For more information, get Portfolio Grader’s complete analysis of NGD stock.

The price of Bill Barrett Corporation (BBG) has fallen 56.5% since the first of the year. Bill Barrett explores for and develops oil and natural gas in the Rocky Mountain region of the United States. As of Aug. 13, 2015, 31.3% of outstanding Bill Barrett Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of BBG stock.

The price of 3D Systems Corporation (DDD) is down 57.7% since the first of the year. 3D Systems engages in the design, development, manufacture, marketing, and servicing of 3D printers and related products, print materials, and services. As of Aug. 13, 2015, 31% of outstanding 3D Systems Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of DDD stock.

Shares of Cliffs Natural Resources (CLF) have slumped 59.7% since January 1. Cliffs Natural Resources is an international mining and natural resources company. As of Aug. 13, 2015, 43.8% of outstanding Cliffs Natural Resources shares were held short. For more information, get Portfolio Grader’s complete analysis of CLF stock.

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

Since the first of the year, Helix Energy Solutions Group, Inc. (HLX) has dipped 63.6%. 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 January 1, Ocwen Financial Corporation (OCN) has fallen 67.1%. Ocwen Financial is a diversified financial services holding company. As of Aug. 13, 2015, 22.1% of outstanding Ocwen Financial Corporation shares were held short. For more information, get Portfolio Grader’s complete analysis of OCN stock.

Since the first of the year, Stone Energy Corporation (SGY) has dipped 71.7%. 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. 13, 2015, 15.7% 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 fallen 75% since January 1. 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.

The price of Peabody Energy Corporation (BTU) is down 87.2% since the first of the year. Peabody Energy mines steal, coal, and metallurgical coal to sell to electric utilities and industrial customers. As of Aug. 13, 2015, 36.5% 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.