Twenty new companies joined the popular Halter USX China Index (NYSEArca: HXC), which tracks the shares of Chinese companies listed on the U.S. stock exchange. The index is the basis for the $425 million PowerShares Golden Dragon Halter USX China Portfolio (NYSEArca: PGJ).

The new constituents are mostly small Nasdaq-listed companies with market capitalizations under $2 billion. The companies are engaged in a broad spectrum of growth industries ranging from health care and technology to energy.

Most of the new additions are handily outperforming traditional benchmarks this year. For example, China Auto Logistics (NasdaqCM: CALI) is up 50 percent year-to-date and Harbin Electric (NasdaqGM: HRBN) has more than doubled. Changyou (NasdaqGS: CYOU), which debuted in April this year, has risen 77 percent, despite having lost a quarter of its value since it peaked in the summer.

HXC ended the third quarter 10.6 percent higher, outperforming most related China benchmarks.

HXC is an index designed for investors who want Chinese equity exposure, but wish to keep their investments focused in U.S.-listed stocks. Including the new additions, the index now comprises 139 companies whose market capitalizations have remained over $50 million for the previous 40 trading days.

For a full list of the companies in the index, you can view the press release here.