Mercer is poised to announce the acquisition of Westpac Banking Corporation (ASX:WBC)'s BT Super unit, according to sources. It is understood that the corporate super fund manager will also purchase Advance Asset Management, a subsidiary of Westpac. Mercer was tipped to buy the business by DataRoom on May 18.

Westpac's super business manages $45.4 billion of funds. It is understood that while Mercer will buy the Advance fund-of-funds business, it will take on BT Super through a successor fund transfer where it makes no payment to secure the business. The super unit is part of Westpac's broader BT Panorama wealth management platform, which is also for sale through investment bank Morgan Stanley.

DataRoom revealed plans to sell the super book separately to the wealth management unit last year.