CareSuper chief executive Julie Lander will lead the merged super fund, if the union with Asset Super goes ahead.

"Realistically, you would expect the larger partner to take the running. That is certainly the way I would see it operating," Asset Super chief executive John Paul told InvestorDaily on Friday.

Paul said he would probably not join the merged entity.

"I think that you should have one CEO [chief executive officer] and not two," he said.

"I don't think it is healthy to have a CEO of the merged fund hanging around keeping an eye on the other CEO."

"Given my age, I'm 63 next year, it is not inappropriate for me to be looking at moving on."

"I would probably be looking at retirement, but you can never say never," Paul said.

The merger was partly inspired by the upcoming changes under the Stronger Super reforms, in particular the proposed requirement for trustees to look at whether their fund has sufficient scale.

"The government is keen for funds to look at merging where it makes sense," Lander said.

"We think [the combined fund] is a good size, it gives us scale," she said.

"But CareSuper has demonstrated that when looking at the top performing funds it isn't all down to the big funds under management," she said.

"Whilst this should give us greater scale in terms of investments, it is about other costs and services as well."

CareSuper and Asset Super have the same administration provider in Australian Administration Services and custodian in National Asset Servicing, but they have different insurance providers.

CareSuper has Comminsure, while Asset Super makes use of MLC for its insurance products.

The two funds also have different asset consultants with CareSuper being advised by JANA and Asset Super by Mercer.

"That is something that we will have to work through over the next months," Lander said.