Industrial production in South Korea was down a seasonally adjusted 0.2 percent on month in September, Statistics Korea said on Thursday.
That was well shy of forecasts for an increase of 1.2 percent following the 4.4 percent gain in August.
On a yearly basis, industrial production sank 1.3 percent - again shy of expectations for a gain of 0.2 percent after adding 3.8 percent in the previous month.
The stats bureau also said that retail sales slumped 0.4 percent on month after rising 1.7 percent a month earlier.