Robert Benmosche will step down as CEO of AIG on September 1, to be replaced by current AIG Property Casualty CEO Peter Hancock.

Mr Benmosche, who is being treated for cancer, initially planned to leave in 2012 but changed his mind.

He will maintain his association with AIG through an advisory role – including to the new CEO – and as a leadership mentor for managers.

London-born Mr Hancock joined AIG in 2010 after serving as vice chairman of banking and financial services group KeyCorp.

He is a former CFO and CRO with JP Morgan and co-founder of risk advisory group Integrated Finance.

At JP Morgan he established the global derivatives group, and he is recognised by many as “the father of credit derivatives” – the financial instruments that helped push the global financial system, and AIG, to the brink in 2008.

Mr Benmosche joined AIG in 2009 and is credited with rescuing it from near-certain collapse.

Under his leadership the global insurer repaid a $US182 billion ($193.4 billion) bailout received from the US Government.

Saving AIG meant halving the size of the company, with major job losses and asset sales.

But Chairman Robert Miller says it is now “a far stronger company than it was five years ago” and “the crisis [is] well behind us”.

“Under Bob’s incomparable leadership and vision, AIG has achieved remarkable, and at times unthinkable, milestones and successes,” he said.