Social Finance Inc., the online-lending platform known as SoFi, is planning an initial public offering that would value the company at $3.5 billion, people with knowledge of the matter said, almost triple what it received in a recent funding round.

The company may raise $500 million this year, said the people, who asked not to be named because the information is private. The San Francisco-based startup plans to file its prospectus confidentially in the second quarter and proceed in the second half, the people said. That timeline may change depending on market conditions.

SoFi would follow online-lending pioneer LendingClub Corp. in tapping public markets. LendingClub was the first marketplace lender to hold an IPO, and now has a valuation of about $7.4 billion. SoFi, with 200 employees, started in 2011 as a peer-to- peer lending company for Stanford University students and graduates — with funds crowd-sourced from the school's alumni. It has since expanded nationally with offerings including mortgages and personal loans.

SoFi is planning to work with Goldman Sachs Group Corp. and Morgan Stanley on the IPO, said the people, though Chief Executive Officer Michael Cagney hasn't decided which firm will be the lead bank. Goldman Sachs has a history with the company, the people said: it helped SoFi to raise $200 million last month at a valuation of $1.3 billion, from investors including Third Point Ventures and Wellington Management Co.

A representative for SoFi declined to comment, as did a spokesman for Goldman Sachs. A representative for Morgan Stanley wasn't immediately reachable for comment.

Student Loans

So far, SoFi has generated more than $1.75 billion in loans, saving borrowers an average $11,783, according to its website.

Student loans are a ripe area for startups. The climbing cost of college has helped swell total student debt to almost $1.2 trillion, with the federal government holding or backing more than $1 trillion of that amount, the U.S. Consumer Financial Protection Bureau said last year. More than 90 percent of all loans for the last academic year were government backed, according to the College Board.

Under the Jumpstart Our Business Startups Act, companies with less than $1 billion in revenue can file for an IPO with the U.S. Securities and Exchange Commission privately and work out the details with the SEC outside the public eye.