(By Emily Backus) (ANSA) - Milan, December 16 - Luxury winter-wear company Moncler saw its stock price soar more than 40% to over 14 euros at its Monday debut on the Milan bourse. Book orders last Wednesday were oversubscribed by a factor of 30 leading up to the initial public offering (IPO), with 20 billion euros worth of demonstrated investor interest for shares. The stock debuted at its fixed maximum price of 10.2 euros, giving the company an initial market capitalisation of 2.5 billion euros. With investors scrambling for shares, its value climbed by a billion euros in just hours to reach more than 3.5 billion. Luxury fashion investors buying stock in Moncler included Salvatore Ferragamo, Ermenegildo Zegna, Loro Piana, LVMH owner Bernard Arnault and Diesel founder Renzo Rosso. Ninety percent of the float was reserved for institutional investors, with the sovereign wealth funds of Qatar, Singapore, China and Abu Dhabi among them. "We are entering the stock market with respect and seriousness," Moncler's chief Remo Ruffini declared at the IPO ceremony at the Milan bourse. As president, chief executive and creative director, Ruffini vowed not to keep his eye on the stock price day by day but to "remain concentrated on my daily work". "We entered the stock market for transparency toward investors, a story I truly believe in," Ruffini added. Moncler made a first attempt at an IPO in 2011, and is backed by three private equity firms, Ruffini told CNN in an October interview. The quilted-jacket maker, founded in France in 1952, built an early reputation for technical garments for icy expeditions and winter sports. Ruffini bought the company in 2003. Over the course of a decade, he transformed it into a glamourous brand of winter wear with exclusive lines showcased on the fashion catwalks of Paris, New York and Milan. But Ruffini's real business target is high-end jacket-wear for any global context. "I changed the strategy from mountain wear to jacket wear," Ruffino told CNN, "and one that is not too much in the fashion system". Ruffino explained that its lines are not pegged to the creative reputation of any single designer, and aims for "jackets you can wear for 6-7 years" as well as other winter clothing staples. Moncler opened its first monobrand store in 2007, and now has about 115 stores worldwide. Europe represents 50% of total brand turnover, followed by Asia at 30%, Ruffino added. The banks that handled the IPO were Goldman Sachs, Mediobanca and Merrill Lynch.