South Korean insurance companies saw their net income jump 17.3 percent in the first nine months of the year from a year earlier on gains from investment, the financial watchdog said Wednesday.

The combined net income of local life and non-life insurers reached 6 trillion won ($5.1 billion) in the January-September period, compared with 5.1 trillion won the previous year, according to the Financial Supervisory Service.

Life insurance firms posted a 19.6 percent on-year rise in profit to 3.7 trillion won during the nine-month period, while non-life insurers' bottom lines gained 13.7 percent to 2.3 trillion won.

Increased investment returns contributed to their strong bottom lines, with life insurers reaping 16.2 trillion won from investment in the first three quarters, up 1.3 percent from a year earlier.

Non-life insurers posted a 15.1 percent on-year gain in investment returns over the same period at 4.8 trillion won.

The return on assets, a key gauge of profitability, grew 0.04 percentage point to 0.89 percent as of end-September.

The insurance companies' combined assets stood at 926.8 trillion won in September, up 11.4 percent on-year from 831.8 trillion won. (Yonhap)