South Korea's main bourse has underperformed most advanced markets so far in the second half of the year due to a lack of growth momentum amid negatives at home and abroad, industry sources said Monday.

The benchmark Korea Composite Stock Price Index finished at 2,019.42 as of Friday, up 2.49 percent from the end of June, according to Daishin Securities Co. and other industry sources.

The increase was much lower than the average gain of 6.71 percent for the key stock indexes of the Group of 20 (G-20) advanced economies over the cited period and placed 15th among them.

Brazil, which hosted the 2016 Summer Olympics, posted the highest growth rate of 24.8 percent, trailed by Argentina with 21.69 percent, Japan with 12.91 percent, Germany with 10.50 percent and Indonesia with 7.85 percent.

Only three of the G-20 countries -- Australia, Saudi Arabia and South Africa -- saw their key stock indexes drop during the period.

Australia's benchmark stock index declined 0.50 percent over the cited period, with Saudi Arabia and South Africa registering falls of 1.19 percent and 3.28 percent, respectively.

The KOSPI's relative underperformance was attributed to a dearth of upward momentum amid a series of unfavorable domestic and external factors.

The KOSPI, which rose as high as 2,070 early last month, has failed to find upward momentum due to renewed concerns over a possible US rate increase late this year, North Korea's fifth nuclear test and Samsung Electronics Co.'s permanent retirement of its latest smartphone Galaxy Note 7 over safety worries.

On top of that, decreased third-quarter earnings by Samsung Electronics, Hyundai Motor Co. and other large-cap companies, put downward pressure on the KOSPI, according to analysts.

Samsung's third-quarter operating profit slipped 29.6 percent from a year earlier, with top automaker Hyundai Motor reporting a

7.2 percent drop in its net profit due largely to a sharp fall in domestic sales caused by a series of labor strikes.

"Overall, the stock markets of the G-20 countries rose considerably in the second half, buoyed by expectations for policy coordination by major economies and timed with the earnings season," said Kim Se-chan, a researcher at Daishin Securities. "But the domestic bourse chalked up only a modest gain as investor confidence in corporate earnings and the effectiveness of government policy measures was not so high."

Market watchers warned the upcoming US presidential election and a potential US rate hike, combined with a snowballing influence-peddling scandal involving an alleged longtime confidante of President Park Geun-hye, could further dishearten investors down the road. (Yonhap)