(Reuters) - Shares of gene-regulation startup Sana Biotechnology Inc surged 40% in their U.S. stock market debut on Thursday, giving the Seattle-based company a market capitalization of $6.38 billion. It offered 23.5 million shares in its initial public offering (IPO) on Wednesday, raising about $587.5 million in what was the largest-ever IPO for a preclinical biotech company. The company’s shares opened at $35, well above the IPO price of $25 per share. Sana, founded in 2018, is led by several co-founders of another Seattle-based biopharmaceutical company, Juno Therapeutics, which is a unit of Bristol-Myers Squibb Co. The biotech firm has raised a total of around $865 million in funding so far from investors including venture capital firm Arch Venture Partners and Canada Pension Plan Investment Board, according to data from PitchBook. Morgan Stanley, Goldman Sachs, J.P. Morgan and BofA Securities were the lead underwriters for the offering.