South Korea's major business groups saw their operating profits plunge nearly 40 percent in the first half from a year earlier.

According to data by industry tracker CEO Score on Sunday, the combined operating profit of 55 of the top 100 listed firms that announced their first-half operating profits came to 42-point-eight trillion won, down 39-point-eight percent from a year earlier.

Over the cited period, their sales inched up one-point-two percent to 592 trillion won.

The decrease was mainly attributed to Samsung Electronics and SK Hynix, the country's top two chipmakers, whose operating profits plummeted 57-point-nine percent and 79-point-eight percent, respectively.

The two firms accounted for over 90 percent of the combined losses.