This year, the won climbed 1 percent versus the US dollar, trailing a gain of 2.7 percent in the Chinese yuan, Asia’s best performance.
Elsewhere in Asia this week, India’s rupee increased 0.3 percent to 61.8450 per US dollar and the ringgit was little changed at 3.2877.
The Philippine peso gained 0.3 percent to 44.380 and Vietnam’s dong rose 0.1 percent to 21,095. China’s yuan traded at 6.0686, compared with 6.0713 on Dec. 20.
The euro rallied for the sixth time in seven weeks on optimism the region’s economy will continue to rebound from contractions last year and this year following the financial crisis.
The 17-nation currency gained as the current-account surplus widened to 21.8 billion euros (US$30 billion) in October, the highest since 1997, while a report on Thursday is forecast to confirm that eurozone factory output grew at a 31-month high this month.
The euro climbed 0.6 percent to US$1.3749 this week in New York, and reached 1.3893, the highest since October 2011.
The euro rallied 1.6 percent to ￥144.59, a seventh straight week of gains, while the Japanese currency fell 1 percent to ￥105.17 per US dollar, its ninth weekly drop, the longest streak since February.
The Swiss franc’s 1.7 percent gain against the greenback led its 16 major peers this month, while South Africa’s rand declined 3.4 percent, the biggest loser.
The currency of Africa’s largest economy was also the worst performer this year, having lost 19.5 percent.
The euro and Danish krone were the biggest winners, having rallied 4.2 percent.
The real was the best performer among major currencies this week after the central bank on Dec. 18 said it will extend its intervention announced in August to support the currency and limit import price increases.
Brazil is to auction US$200 million of foreign-exchange swaps on trading days from next month through at least the end of June, down from offerings of US$500 million four days a week this year.
The currency surged 2.1 percent to 2.3383 per US dollar this week, the biggest five-day advance in three months.
The lira tumbled for a fifth week amid a showdown between the government and judicial powers.
Turkey’s currency slumped 3 percent from the end of last week to 2.1549 per dollar after dropping to an all-time low 2.1764.