SEOUL (Reuters) - South Korean firm SK Bioscience Co Ltd shares rocketed 30% on their first day of trading on Thursday, as investor bets on the COVID-19 vaccine developer and maker’s prospects turned it into a nearly $12 billion business. The stock opened on Seoul’s KOSPI market at 130,000 won per share, double the initial public offering (IPO) price of 65,000 won, then quickly jumped to 169,000 won in early trade, valuing the company at 12.9 trillion won ($11.5 billion). The 30% surge, after the biggest IPO in Seoul in nearly four years, was the best opening-day performance on the KOSPI since global EV parts supplier Myoung Shin Industry listed in December. Analysts said the successful listing continues the trend of a busy IPO market in South Korea this year. Robust investor demand is expected to fuel more listings by companies in sectors seen profiting from increased health concerns and stay-at-home habits driven by the COVID-19 pandemic. The vaccine developer, in which SK Chemical holds a 68.4% stake, raised 1.5 trillion won in the country’s largest IPO since mobile game developer Netmarble raised 2.7 trillion won in May 2017, according to Korea Exchange data. SK Bioscience has agreements to produce COVID-19 vaccines for AstraZeneca and Novavax Inc in Korea, and received regulatory approval in November to begin clinical trials of its own COVID-19 vaccine. “SK Bioscience gained an opportunity to become a global vaccine company by being chosen to develop and produce for the COVID-19 vaccine purchasing scheme known as COVAX,” said Han Byung-hwa, analyst at Eugene Investment & Securities. COVAX is the World Health Organization-backed programme to provide vaccines for poor and middle-income countries. “It’s the only company chosen that conducts development and manufacturing simultaneously,” said Han, speaking before the shares began trading. “After (vaccine) approval, revenue will begin to come in the second half.” SK Bioscience’s IPO raised more than last year’s successful listings in business sectors that have thrived during the pandemic, such as game developer Kakao Games and affiliate SK Biopharmaceuticals. “Interest (in South Korean IPOs) is sky high from both institutions and retail investors, and liquidity is abundant. This is expected to continue,” said Park Jong-sun, analyst at Eugene Investment & Securities, speaking before the SK Bioscience debut.