The $750 million development will see a 50-50 joint venture between the two companies.
The old Westpac building was built in 1971 and will be demolished to see the development of the new tower which is said to be constructed by the end of 2018.
It was reported in The Australian that the tower is expected to sit 33-storeys high and have a NLA of 30,000 square metres and a GA of 44,000 square metres.
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Investa Office Head of Capital Transactions, Commercial Development and Leasing Michael Cook
told The Australian that a formal design competition for shortlisted parties is expected to commence within a month.
Investa has reportedly come to an agreement with the adjacent heritage listed St Stephen's Uniting Church to amalgamate their land titles, allowing for a bigger structure.
Investa will provide the church weekend carpark access in return as well as possible financial contributions.