South Korea's top mobile messenger operator Kakao, No. 1 mobile carrier SK Telecom Co. and others submitted preliminary bids on Tuesday to buy eBay Korea in a deal that could fetch some 5 trillion won ($4.42 billion) and bring a seismic change to the fiercely competitive e-commerce sector, industry sources said.

Retail giant Lotte Group and Emart Inc., a discount store chain affiliated with Shinsegae Group, as well as private equity firm MBK Partners, joined the competition for the nation's No. 3 e-commerce operator, they added.

The preliminary bids for eBay Korea, which operates major online shopping sites, including Gmarket, Auction and G9, came as major players are seeking merger and acquisition (M&As) and business cooperation to survive in the country's e-commerce and retail sectors.

Annual transactions on eBay Korea's online shopping sites reached some 20 trillion won last year, which means the acquisition could help a winner stand on par with top portal operator Naver and e-commerce giant Coupang. The value of annual e-commerce transactions on Naver was estimated at 27 trillion won last year.

The most aggressive prospective investor is known to be Kakao, the operator of Kakao Talk, the country's most popular mobile messaging app, which has been seeking to bulk up its e-commerce business.

Market observers also tipped Lotte Group and Shinsegae's Emart as strong candidates for the eBay Korea deal.

Lotte is seeking to boost its online mall Lotte ON, and Shinsegae wants to expand its online mall SSG.Com.

The deal could also help SK Telecom, the operator of online mall 11Street, to tighten its grip on the e-commerce market, they noted.

Earlier in the day, Naver and Shinsegae agreed to a share swap deal valued at 250 billion won to strengthen their foothold in the e-commerce sector.

Last week, Coupang made a successful debut on the New York Stock Exchange.

Coupang's initial public offering, which raised $4.6 billion, was the largest by a foreign company on Wall Street since China's Alibaba in 2014. (Yonhap)