* Kakao Bank trading at 65% above IPO price * The purely digital bank gained $25 bln in assets in four years * “It’s a platform, not just a bank” - analyst (Recasts and adds analyst quote) SEOUL, Aug 6 (Reuters) - Digital lender Kakao Bank Corp made a stunning debut on Friday, surging 65% from its IPO price to become South Korea’s biggest financial services firm by market value. The country first purely mobile bank to go public is expected to capitalise on rare growth opportunities for a financial firm afforded by an unusual South Korean regulatory framework. Unlike many traditional lenders, Kakao Bank is able to sell and collect fees on products offered by other financial firms and also has an advertising business. “Shareholders are bullish as it’s a platform, not just a bank. It’s a whole new type of firm, made possible due to South Korea’s unique regulatory environment,” said Seo Young-soo, an analyst at Kiwoom Securities. Its shares were changing hands at 64,600 won in late morning trade on Friday, compared with its IPO price of 39,000 won and valuing it at roughly $26 billion. By contrast, KB Financial Group Inc, South Korea’s biggest traditional financial group, was worth about $19 billion. Kakao Bank became profitable in 2019 after less than two years in operation and has 13.35 million monthly active users, making it the largest financial app in the country. “It’s the only purely mobile digital bank in the world that has grown into a large bank with 28.6 trillion won ($25 billion) in assets in just four years,” said Seo. It made 804.2 billion won in operating profit last year, three-quarters of which was interest income. Platform-related businesses still only account for 6% of its income. Its largest shareholder is Kakao Corp, operator of South Korea’s dominant chat app, with a 27.3% stake. The listing is the country’s biggest since game company Netmarble’s IPO raised 2.7 trillion won in 2017, continuing a bumper year for South Korean stock market floats, although some valuations have been slashed in recent offerings.