The past half-decade has been a gold rush for new online lenders. With banks drowning in regulation and the explosion of big data opening the space to more upstarts, a wave of Web-based lending companies have emerged with the goal of luring more consumers.  The Federal Reserve's zero interest rate policy has also certainly helped. Yield-starved investors desperate for fixed-income returns have essentially played the role of bank roller, pouring money into new lending platforms.  Known as marketplace lenders, these companies originated nearly $9 billion in loans in 2014, up from about $100 million in 2009, according to venture firm Foundation Capital. While some of that money has been funded by banks, the majority has come from private equity firms, hedge funds, family offices and retail investors.  Read MoreWhy start-ups need to start listening to the Fed  Now that Fed Chair Janet Yellen has indicated the Fed funds rate will rise above zero for the first time in more than six years, a key question is whether these investors will flock back to Treasurys and corporate bonds, removing tech start-ups' easy money punch bowl.  For now, that's not happening. Just this week, 4-year-old SoFi, which refinances student debt and offers mortgages and personal loans, said it had crossed the $2 billion mark for loans issued. SoFi has enough growth mojo that it's starting a competition whereby it will forgive one student loan—of up to $600,000—per quarter.  Read MoreDrowning in student debt? Maybe you can refinance  And Upstart, a fresh entry into the online lending market, got a big vote of support from private equity firm Victory Park Capital, which said it's increasing its commitment to finance $500 million worth of personal loans, up from $100 million.  "Their results give us confidence that this emerging [lending] platform is serving a critical market need," said Tom Welch, a principal at Victory Park, in a statement.  Of course, few doubt higher interest rates could eventually hurt these new lenders. Loans are sensitive to rates, so prices have to rise to protect margins. But for now, the demand for marketplace loans is soaring.
Web lenders have proliferated during six years of record low interest rates. With the Fed signaling rate hikes, they must navigate new terrain.