KakaoBank Corp., a South Korean internet-only bank, Tuesday reported a 43.2 percent jump in its first-quarter earnings as its customer base continued to expand amid the coronavirus pandemic.

Net income came to 66.80 billion won (US$52.8 million) in the January-March period, compared with 46.66 billon won tallied a year earlier, the company said in a regulatory filing.

Operating profit also surged 63.8 percent on-year to a record quarterly high of 88.41 billion won, with sales advancing 50.5 percent over the same period to 338.44 billion won.

The robust earnings came as the number of its customers increased by some 620,000 on-quarter to 18.61 million at the end of March. The rise stemmed mostly from an increase among those in their 40s and 50s, the company said.

Market watchers said growing demand for mobile banking amid the protracted pandemic also played a role in boosting KakaoBank's earnings in the latest quarter.

In particular, the bank's net interest margin -- a key barometer of profitability that shows the difference between interest paid and interest received -- rose to 2.22 percent in the first quarter from the previous quarter's 2.13 percent. It was also higher than the previous year's 1.87 percent.

The improved profitability was thanks to the overall lending rate hikes in line with the central bank's recent move to increase borrowing costs intended to tame inflation and its increased extension of credit, the company said.

As of end-March, KakaoBank held 33.04 trillion won in deposits, while its outstanding credit came to 25.97 trillion won.

Sales from its platform business grew 38.5 percent on-year to 25.3 billion won, and revenue from transaction fees also rose 18.8 percent to 47.7 billion won, the company said.

Shares of KakaoBank were trading up 0.61 percent on Seoul's main bourse as of 10:48 a.m., outperforming the KOSPI's 0.22 percent rise. (Yonhap)