Funder-backed securities class actions are driving directors' and officers' insurance (D&O) to unaffordable levels, with some premiums increasing by more than 200 per cent a year, according to insurance broker Marsh.

Appearing before the Parliamentary Committee on Corporations and Financial Services on Monday, Scott Leney, chief executive of Marsh, Australia's largest C-suite insurance broker, said the impact of securities class actions had reverberated through all D&O insurance policies.