A type of bonds are emerging in the United States similar to what's known as Ninja or subprime mortgages, those given to people with no income, jobs or assets.
When the global financial crisis first hit, these loans were packaged up and sliced and diced into bonds which were sold to a wide range of banks and pension schemes.
Then borrowers began defaulting.
Radio New Zealand's business editor reports that now, an eerily similar type of bonds is emerging in the US.
Financial gurus have been buying up abandoned houses once owned by the Ninjas, muscling out other home buyers and driving up both house prices and rents.
They rent the houses and package the resulting income into bonds which they on-sell to investors, a process known as securitisation.
The biggest company involved so far is Dallas-based Invitation Homes, backed by Blackstone, the world's largest private equity firm.
Merchant banks such as Credit Suisse and JP Morgan, are also involved.
Last week, more than 75 US housing and consumer groups wrote an open letter to US regulators warning that, left unchecked, these new type of bonds could spur another crisis.
One of the signees, the executive director of Housing and Economic Rights Advocates, Maeve Elise Brown, says these bonds are dangerous.
She says the roof over somebody's head should not be subject to someone else's gambling game.
Ms Brown says the new bonds are just like mortgage-backed securities with a twist and investors in them are dependent on rents being paid for their income.
She says that means there will be an urge to keep increasing rents endlessly beyond what the market can bear and up to a point there will be less interest in investing in the property which could mean poor building maintenance.
Already, there are maintenance problems and people being forced to live in sub-standard homes.
Another signee, California Reinvestment Coalition associate director Kevin Stein says securitisation of rents is exacerbating an already big problem.
He says investors are buying up many of the foreclosed properties in communities and preventing people who want to buy those properties from purchasing them and often displacing tenants in violation of tenant protection laws.
Ms Brown says one hopeful sign is that at least one of the major ratings agencies, Fitch, has refused to rate rental bonds.
Those who signed last week's letter say if regulators fail to take action now, another crisis may be in the making.