Kakao Corp., the operator of South Korea's top mobile messenger KakaoTalk, on Thursday said its second-quarter net profit moved down 5.6 percent on increased costs and tax payment.

Net profit reached 12.5 billion won ($10.9 million) on a consolidated basis in the April-June period, compared with 13.2 billion won the previous year, the company said in a regulatory filing.

But its operating income surged 67.7 percent on-year to 44.6 billion won, and sales rose 24.4 percent to 468 billion won. 

The net profit fell below 25.8 billion won, which was estimated by 32 brokerage houses, compiled by Yonhap Infomax, the financial arm of Yonhap News Agency.

Kakao said its operating expenditures increased 21 percent on-year to reach 42.3 billion won. Its tax payment also shot up 198 percent on-year to reach 23.5 billion won in the second quarter, it added.

Kakao said sales from its advertisement platforms moved up 11 percent on-year to reach 151.4 billion won, largely helped by the mobile segment.

Its content business also saw a 24 percent rise in revenue of 236.2 billion won on the back of a rising number of users for Melon, its music-streaming service.

The music-streaming service posted sales of 117.1 billion won, up 29 percent on-year, with its gaming content also posting sales of 78.7 billion won.

Kakao also raked in 80.8 billion won from other businesses, including products made with "Kakao Friends" characters.

Shares of Kakao opened 1.38 percent higher on the main bourse at 110,000 won Thursday. The second-quarter report was released before the market opened. (Yonhap)