South Korea's foreign reserves fell for a second straight month in September due to the US dollar's rise and market stabilization measures, central bank data showed Friday.

The country's foreign reserves had come to $414.12 billion as of end-September, down $4.18 billion from the previous month, according to the data from the Bank of Korea.

The dollar's ascent last month reduced the converted value of holdings denominated in other currencies, the BOK explained.

The dollar index that gauges the greenback's value against major peers rose 3 percent last month, the central bank said.

Foreign reserves consist of securities and deposits denominated in overseas currencies, International Monetary Fund reserve positions, special drawing rights and gold bullion.

Foreign securities, such as US Treasuries, had been valued at $372.59 billion as of end-September, down $6.44 billion from a month earlier. They accounted for 90 percent of foreign reserves, the data showed.

The value of deposits stood at $17.4 billion at the end of September, up $2.56 billion from a month earlier.

South Korea ranked as the world's ninth-largest holder of foreign reserves at the end of August, the BOK said. (Yonhap)