South Korea's foreign reserves increased for the second straight month in December on the back of the increased conversion value of non-dollar assets and a rise in deposits, South Korea's central bank data showed Thursday.The country's foreign reserves had come to $420.15 billion as of end-December, up $3.07 billion from the previous month, according to data provided by the Bank of Korea (BOK).The dollar's descent last month boosted the converted value of holdings denominated in other currencies, and investment returns increased, the BOK explained, according to Yonhap News Agency.The dollar index that gauges the greenback's value against major peers dropped 1.5% 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 $373.67 billion as of end-December, up $1.6 billion from a month earlier. They accounted for 88.9% of foreign reserves, the data showed.The value of deposits stood at $21.98 billion at the end of December, up $1.38 billion from a month earlier. (QNA)