This week, these ten stocks, all currently earning A’s (“strong buy”) on Portfolio Grader, have the best year-to-date performance.

Since January 1, Impax Laboratories, Inc. (IPXL) has jumped 47.3%. Impax Laboratories develops, manufactures, and markets both proprietary and multi-source pharmaceutical products utilizing its drug delivery technologies. Trade volume has increased significantly over the past week, up 163.3%. For more information, get Portfolio Grader’s complete analysis of IPXL stock.

Since January 1, Insperity, Inc. (NSP) has shot up 49.3%. Insperity provides personnel management that encompasses a range of services, including benefits and payroll administration, health and workers’ compensation insurance programs and personnel records management. For more information, get Portfolio Grader’s complete analysis of NSP stock.

Shares of Stamps.com (STMP) have risen 55.1% since January 1. Stamps.com is an Internet-based company that allows customers to send mail. For more information, get Portfolio Grader’s complete analysis of STMP stock.

The price of Cigna (CI) is up 60.9% since the first of the year. CIGNA provides health care and related benefits, such as life and accident insurance, health care products, and workers’ compensation case management. For more information, get Portfolio Grader’s complete analysis of CI stock.

Since January 1, Ellie Mae, Inc. (ELLI) has climbed 70.2%. Ellie Mae provides business automation software for the mortgage industry in the United States. For more information, get Portfolio Grader’s complete analysis of ELLI stock.

Since January 1, the price of China Biologic Products, Inc. (CBPO) has grown 73%. China Biologic Products is a biopharmaceutical company that engages in the research, development, manufacture, and sale of human plasma-based biopharmaceutical products to hospitals and inoculation centers. For more information, get Portfolio Grader’s complete analysis of CBPO stock.

Since the first of the year, shares of ABIOMED, Inc. (ABMD) have soared 82%. Abiomed provides medical devices in circulatory support and it offers a continuum of care in heart recovery to acute heart failure patients. For more information, get Portfolio Grader’s complete analysis of ABMD stock.

Since January 1, Ebix, Inc. (EBIX) has jumped 95.8%. Ebix provides a series of application software products for the insurance industry, including carrier systems and agency systems. For more information, get Portfolio Grader’s complete analysis of EBIX stock.

Since the first of the year, the price of Skechers U.S.A., Inc. Class A (SKX) has swelled 97.3%. Skechers USA designs, makes, markets and distributes footwear. The volume of trades has grown significantly in the past week, up 751.9%. For more information, get Portfolio Grader’s complete analysis of SKX stock.

Chimera Investment Corporation (CIM) has risen 305.9% since the first of the year. Chimera Investment is a specialty finance company that invests in residential mortgage-backed securities, residential mortgage loans, real estate-related securities, and various other asset classes. The stock has a trailing PE Ratio of 5.10. For more information, get Portfolio Grader’s complete analysis of CIM 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.