South Korean shares ended at a one-week low on Friday after North Korea conducted its fifth nuclear test and said it had mastered the ability to mount a warhead on a ballistic missile. The Korea Composite Stock Price Index (KOSPI) closed down 1.3 percent at 2,037.87 points. Foreign investors ended a five-day buying streak and sold a net 115.2 billion won ($104.91 million) of KOSPI shares for the day. The South Korean won pared early losses caused by the nuclear test as the exporters sold the greenback later in the session. The won was quoted at 1,098.4 to the dollar at the conclusion of onshore trade, down 0.5 percent from Thursday's close of 1,092.6. The currency gained 1.7 percent for the week, its biggest weekly gain in seven weeks.