Moody’s has put the debt ratings of Genworth Financial Inc and the insurance financial strength ratings of its US mortgage insurance companies on review for downgrade.

About $US4.3 billion ($4.2 billion) in debt is affected.

The ratings agency has also downgraded the insurance financial strength ratings of Genworth’s primary life insurance operating subsidiaries from A2 to A3 with a stable outlook.

Moody’s Senior VP Scott Robinson says the downgraded US life rating reflects Genworth Life’s weaker credit profile compared with its peers.

Genworth Mortgage Insurance Corp has been placed on review for downgrade due to uncertainty about the strength of its parent, which is also under review.

Moody’s notes weak credit trends in the US housing market and says there is uncertainty about the role of private mortgage insurers following reform of the mortgage sector.