South Korea's market for a type of unsecured debt security, or exchange traded note, posted rapid growth, thanks to robust demand for risk-hedging investments, the nation's bourse operator said Monday.

The market's total value has grown to 3.9 trillion won ($3.3 billion) as of the end of June this year from 466.1 billion won in November 2014.

In terms of market value, South Korea's ETN market came second after the United States, which had a value of 16.5 trillion won in its ETN market, the Korea Exchange said in a statement.

The number of listed products jumped to 155 from 10 at the time of its debut.

ETNs are a type of unsecured debt security tracking the performance of various market benchmarks. Similar to bonds and exchange traded funds, ETNs are traded on the main exchange during normal trading hours.

Despite the rapid growth, the average daily turnover of ETNs declined this year, the bourse operator said.

The average daily turnover of ETNs during the first-half of this year stood at 22.6 billion won, compared to 32.5 billion won last year. (Yonhap)