Standard & Poor's is expected to agree within days to pay $1.37 billion to settle lawsuits over its rosy grading of mortgage bonds in the financial crisis, sources told AFP Wednesday.

People close to the situation said the powerful rating agency could announce a deal with federal and state justice authorities next week.

S&P is not expected to admit guilt to charges, but to "agree to a statement of facts of wrongdoing" in the cases, one of the sources said.

That would wrap up one of the last major lawsuits concerning the over-grading and deceptive marketing of securities that pulled together in a package millions of often high-risk home mortgages in the years running up to the 2008 financial crisis.

Investors lost billions of dollars on the securities when the housing market crashed and showed that large numbers of the mortgages were highly risky "sub-prime" deals that quickly fell into default.

As major banks, pension funds and other huge institutional investors took heavy losses on the bonds, in 2008 US authorities were forced to step in massively to prevent total collapse of the financial system.

Numerous banks have already paid huge fines and settlements for their roles in packaging and selling the bonds as low-risk, solid investments.