South Korea's leading securities companies posted record earnings in the first nine months of this year on a stock market boom, industry sources said Thursday.

The country's top 10 brokerage housed are estimated to have registered a combined net profit of around 7 trillion won ($5.9 billion) for the January-September period, with their full-year bottom line likely to exceed 10 trillion won.

Their record net profit comes as the local stock market has been on a roll this year on the back of active investment by retail investors.

Korea Investment & Securities Co. chalked up the largest net income of about 1.2 trillion won for the first three quarters, which was up 186 percent from a year earlier.

It was also the largest for the first three months of the year. In the third quarter alone, its net income soared nearly 140 percent on-year to 621 billion won.

Korea Investment & Securities said its record performance was bolstered largely by increased profit from the investment banking business, including management of initial public offerings.

Samsung Securities Co. came next with 821.7 billion won, followed by NH Investment & Securities Co. with 794.3 billion won and KB Securities Co. with 547.4 billion won.

Mirae Securities Co., the top industry player by equity capital, is slated to announce its third-quarter earnings Thursday, with its cumulative net profit estimated at around 1 trillion won for the first three quarters.

Earnings of the remaining brokerage houses -- Hana Financial Investment, Meritz Securities, Kiwoom Securities, Shinhan Investment and Daishin Securities -- range from 300 billion won to 600 billion won for the first nine months.

Yet industry watchers strike a cautious note for the last quarter of the year, saying growing uncertainty of domestic and overseas financial markets, a drop in stock trading and rising interest rates may weigh down their bottom lines in the fourth quarter. (Yonhap)