Businesses and consumers will not be able to borrow more than $2 million a year through peer-to-peer lending, but the amount lenders can lend will be uncapped, the FMA said.
Roberts said overseas peer-to-peer platforms such as the US LendingClub, which is preparing for a US$500 million ($570 million) sharemarket listing, and the UK's Zopa could not keep up with demand from lenders.
Low interest on bank deposits meant people were "yield-starved".
"We're opening up a new asset class to retail investors and we're cutting out the banks," he said.
Lenders could expect an average annual return of 12 per cent.
Loans, expected to be around $15,000 on average, would be broken up into $25 "lots" and distributed among lenders to spread risk, he said.
Interest rates would range from single digits up to around 30 per cent and would on average be "significantly lower than the top four banks".
Roberts said Harmoney's borrowers would be mainly "middle New Zealand consumers" who wanted loans for things such as cars, weddings and funerals or to consolidate credit card debt. Harmoney will charge borrowers a fee ranging from 2 to 5 per cent of the loan's total value, and lenders will have 1.25 per cent taken from their repayments.
FMA director of compliance Elaine Campbell said peer-to-peer lending had great potential, but "lenders should also realise the risks are greater than putting money in a bank".
An FMA spokesman said the regulator was reviewing four applications for equity crowd funding licences and another for a combined peer-to-peer and crowd funding platform.
It is expected to grant its first equity crowd funding licences this month.
