Prosper - like rival outfits Lending Club and Loanio - was forced to close its doors to new loans last year as it looked to register its business with the Securities and Exchange Commission.

That process has not been completed yet but the company says it has received an intra-state exemption from the California Department of Corporations. This means Californian residents and businesses can now make loans with anyone in the US able to borrow.

As well as its traditional P2P lending model, the platform is now introducing an Open Market initiative, where vetted finance companies can post loans on Prosper and invite bids.

All loans will be marked and include information about the company that originated them, while listings must be current and have at least three months of payment history.

Prosper says that because its loans have a one-to-one relationship between the investment and the underlying asset, they're inherently transparent and less complex than traditional debt securitisation.

The firm claims the offering will help unfreeze the credit market, providing banks, credit unions and car finance firms a way to obtain much needed capital they can use to make loans to more people.

Raj Date, board member, Prosper, says: "The Prosper Open Market initiative will help fill the void left by the collapse in asset-backed securitisation."

The P2P lending side of the site will continue to work as before but with the addition of a secondary market, where lenders can buy and sell Prosper loans "notes" to each other.

The site has also tightened up its risk rating system, with loan listings by individuals meet a minimum credit score requirement of 640.

Chris Larsen, CEO, Prosper, says: "Prosper offers an alternative to government bailouts by empowering ordinary Americans to invest and take part in helping rebuild our economy from the ground up."