KT Corp., South Korea's major mobile carrier, said Thursday it shifted to a net loss in the fourth quarter from a profit a year earlier due to an increase in operating costs.

The company said in a regulatory filing it logged a net loss of 41.7 billion won ($31.4 million) in the last three months of 2023 on a consolidated basis, swinging from a profit of 242.7 billion won a year earlier.

Operating income for the October-December period rose 75.4 percent on-year to 265.6 billion won, and sales increased 1.8 percent to 6.69 trillion won.

For the whole of 2023, KT reported a net profit of 988.7 billion won, down 28.8 percent from the previous year.

The yearly operating profit declined 2.4 percent on-year to 1.65 trillion won, despite record annual sales of 26.4 trillion won.

The company said it turned to red in the fourth quarter as its operating costs increased on content buying and a loss from its broadcasting subsidiary KT Skylife Co.

But KT said it hit an all-time high in sales last year thanks to an overall improvement in their business-to-customer and business-to-business units.

Annual sales from KT's mainstay mobile business rose 2.3 percent on-year to 6.87 trillion won on an increase in fifth-generation network service users and stronger demand for roaming services.

Cable sales inched up 1 percent on-year to 5.27 trillion won on increased GiGA internet and IPTV subscribers.

Sales from corporate services also gained 2 percent to 3.46 trillion won on the growth of its artificial intelligence and internet of things businesses, and higher sales from its data business on the back of the digital transformation trend.

KT said it is working to expand its AI business by targeting the private large language model market with its large AI model Mi:dm released last year and investing 33 billion won in AI chip startup Rebellions.

The company said its real estate and cloud service arms also showed robust growth last year.

KT estate Inc. raised 594.5 billion won in sales, up 21.8 percent on-year, and KT cloud Co. saw its sales jump 57 percent on-year to 678.3 billion won.

The mobile carrier said it plans to buy back 27.1 billion won worth of its shares to hand out cash dividends worth 1,960 won per share to its stockholders. (Yonhap)