Ben Bernanke on Friday called for a far-reaching overhaul of the giant credit derivatives and triparty repo markets as part of a push to strengthen the financial system and reduce systemic risk.

The Federal Reserve chairman, speaking at the start of the Fed’s annual retreat in Jackson Hole, said changes were needed to minimise the “moral hazard” that might otherwise result from the rescue of Bear Stearns and other efforts to combat the credit crisis.