More than 3600 former Feltex shareholders are now opted into litigation against the carpet-maker's former directors and an updated list of claimants has been filed with the High Court.
The representative action alleges Feltex's prospectus in 2004 - the year it floated - contained information that was misleading or wrong, or omitted to make information available that would have affected investment decisions.
Feltex collapsed in 2006, causing 8000 investors to lose millions of dollars.
Investors, represented in court by Feltex shareholder Eric Houghton, are seeking a refund of the purchase price of their shares, plus associated interest and costs.
The first part of the case is due to begin in the High Court at Wellington next March and investors had until recently to opt-into the case.