Medibank shareholders have filed a class action against the insurance company, alleging it breached disclosure obligations by not revealing the extent of its security deficiencies.

The class action was filed in the Supreme Court of Victoria and served on Medibank on Wednesday, the company informed the ASX. It is on behalf of those purchased shares between July 1, 2019 to October 2022, when the cyber hack occurred.

The statement of claim includes allegations that Medibank breached its continuous disclosure obligations under the Corporations Act 2001 and ASX Listing Rules by not disclosing to the market information relating to alleged deficiencies in its cyber security systems.

Medibank said it intends to defend the proceedings.