South Korea's first-tier firms by market value saw their profitability improve last year on the back of their cost-cutting efforts and increased sales, industry data showed Monday.

According to the data compiled by industry tracker CEO Score, 75 out of the country's top 100 market cap firms reported a 12.4 percent rise in their operating income at a combined 111.1 trillion won ($96.2 billion) last year, with their combined sales also rising 1.7 percent to 1,344 trillion won.

Of the surveyed firms, 58 logged a rise in their sales last year, while 52 firms posted a hike in their operating incomes.

Samsung Electronics, the top cap firm, posted a 0.6 percent rise in its sales last year and a 10.7 percent hike in its operating income. POSCO, the No. 1 steelmaker, suffered a 15 percent dip in its sales but logged an 18 percent surge in its operating income to 2.84 trillion won.

Hyundai Heavy Industries Co., the leading shipyard here, also racked up an operating income of 1.64 trillion won, while its sales sank 15 percent to 39.32 trillion won.

SK Innovation Co., LG Electronics Inc., S-Oil Corp and others also suffered a dip in their sales but saw improved bottom lines, the data showed. (Yonhap)