AustralianSuper expects to grow to over two million members and $50 billion worth of member assets, after IBM selected it as its default superannuation fund.
The transfer of IBM Super members to AustralianSuper, subject to due diligence, will add 15,000 members and increase funds under management (FUM) by $1.7 billion.
An AustralianSuper spokesperson said the deal was the "largest ever corporate outsourcing in history".
AustralianSuper chief executive Ian Silk said the fund's increasing scale allowed it to provide sustainable results for members.
"IBM's decision is an endorsement of our members-first strategy," he said.
AustralianSuper merged with Westscheme in July 2011, adding $3.4 billion to AustralianSuper's FUM, and is also set to join up with AGEST Super.
If all goes according to plan, IBM Super members and employees will transfer to AustralianSuper on 1 November this year.
Superannuation fees have continued their multi-year decline, as fund consolidation and index investing deliver scale efficiencies for members.
Super funds demand fast passage of payday super laws, while small business advocates warn of cash flow pressures and compliance risks.
The superannuation industry could move faster on personalisation, according to MLC, and the fund has identified three core areas where it will be focusing its personalisation efforts over the next 12 months.
The Actuaries Institute has released a framework to help super funds deliver affordable guidance and advice to millions approaching retirement.