Operating profits of South Korea's listed firms is estimated to have plunged over 40 percent on average in the first quarter.

According to market researcher FnGuide on Sunday, the combined operating profit of 67 firms listed on the country's main bourse KOSPI and the secondary KOSDAQ market was tallied at 19-point-two trillion won in the January-March period.

The figure marks a decrease of 41-point-five percent from a year earlier, with sharp decreases among chipmakers and chemical makers.

SK Hynix reported last week that it posted an operating profit of one-point-three trillion won for the quarter, a 69 percent plunge from the previous year. Samsung Electronics, which is set to release its first-quarter results Tuesday, estimated that its operating profit is likely to plummet about 60 percent for the quarter.