"The administrators' key role is to act for all creditors equally, there's no secured creditor in this case, no bank involved. We are up here working to understand every individual investor's position and what they are entitled to claim as quickly as we can.
"But I'm also not here to sugar coat it. We've been in enough of these jobs recently to know this is going to be heavy court involvement and lengthy in time."
Halifax New Zealand is 70 per cent owned by Halifax Investment Services Australia and 30 per cent by Andrew Gibbs of Auckland.
The firm offered a range of investment products, including foreign exchange, CFDs, shares and options trading. It is regulated by the Financial Markets Authority.
The administrators were meeting daily with regulators in both countries.
They have sought an extension of 90 days to the timeframe before the second creditors meeting due to the complexities of the process and the Christmas holiday period.
"We don't think that within the existing timeframe we'll be able to give creditors a sufficient picture about what has happened … or know what investors are entitled to or where they might sit between Australia and New Zealand," McCullum said. "There are lots of complexities."
Past experience indicated a legally intensive and court intensive process to unravel each class of investors, what rights they hold and whether there is any inter-mingling of funds, he said.
"All of those things are likely to require the voices and input of different classes of investors to assist us through that process."
Another subsidiary, Halifax Asia, is not part of the administration, but there are significant Chinese investors caught up in the collapse and that added further complexity, he said.
Halifax NZ gained a derivatives issuer license from the FMA in June 2015, allowing it to transact a variety of financial instruments including futures, options, forex and CFDs.
Most recent accounts filed to the Companies Office reveal Halifax NZ earned brokerage and subscription revenue of $2.4m in the year to March 31 for a profit of $16,726.
In June 2015 it obtained a $1.2m subordinated loan from its Australian parent to meet its capital requirements.