Shares of LendingClub, the world's largest online marketplace that connects borrowers and investors, rose as much as 67 percent in their debut, valuing the company at more than $9 billion.
The initial public offering of 58 million shares raised $870 million after being priced at $15 per share, well above the expected range of $12-$14.
San Francisco-based LendingClub sold 50.3 million shares, while selling stockholders offered the rest.
LendingClub's shares opened at $24.75 on the New York Stock Exchange and touched a high of $25.44.
The spike means an even bigger payday for early investors. Some of the biggest shareholders' stakes are now worth as much as $1.2 billion (Norwest Venture Partners), $1.15 billion (Canaan Partners) and $925.5 million (Foundation Capital).
Former Treasury Secretary Larry Summers, who is a board member, also owns a stake now worth $23.5 million.
The company's low-cost peer-to-peer platform allows investors to lend directly to individuals and businesses, cutting out banks.
Morgan Stanley, Goldman Sachs and Citigroup were the underwriters to the IPO.
CNBC's Ari Levy contributed to this report.