The Market Vectors Emerging Markets High Yield Bond ETF (NYSEArca: HYEM) is getting a new index.

On or about May 11, HYEM will begin tracking a new benchmark index, the BofA Merrill Lynch Diversified High Yield US Emerging Markets Corporate Plus Index. The ETF currently benchmarks to the BofA Merrill Lynch High Yield US Emerging Markets Liquid Corporate Plus Index (EMHY).

“The new index includes a 10 percent country weighting cap and a three percent cap on individual issuers, while the current index does not include such caps. Van Eck believes that, by including such caps, the new index may help reduce the risks associated with high concentrations in any single country or issuer,” according to a statement from Market Vectors.

No country currently accounts for 10% of HYEM’s weight, though China, Brazil and Russia combine for a quarter of the fund’s weight. The ETF’s top 10 holdings combine for 8.8% of the fund’s weight. HYEM was one of the first ETFs to focus exclusively on the non-sovereign, junk area of the emerging markets debt universe.

High-yield emerging markets corporates have higher yields than their sovereign and U.S. junk counterparts and lower default rates than U.S. non-investment grade corporates.  [An EM Junk Bond ETF Crushes Treasuries]

The ETF, which debuted in May 2012, has $394.4 million in assets under management and a 30-day SEC yield of 9.49%. HYEM’s effective duration is 3.85 years, according to Market Vectors data.