Anthony Pratt is reported to be paying $22 million for a North Bondi home.
The deal for 144 Ramsgate Avenue would be the priciest for a residence in the suburb.
The vendors, CSA Architects director Alex Smith and his wife, spent $3.2m in 2004 before undertaking a major renovation.
On 276 sqm, it previously traded for $690,000 in 1991.
The Wentworth Courier reported the Pratt off-market deal following confirmation by sources (story continues below).
Raine & Horne Double Bay’s Ric Serrao is understood to be the agent.
Any deal would come two years since Mr Pratt and his wife, Claudine Revere, were speculated to have spent $A21.3m on a New York home.
In 2016, the pair developed a contemporary mansion on part of the Raheen estate, in Melbourne’s east Kew.