I understand that the Broadgate West office complex, near Liverpool Street station, is poised to change hands following an on-off auction that has run for more than a year.
The deal could be announced as soon as today.
Valued at around £300m, the sale of the site will reap a sizeable windfall for the American tycoon who was once married to the heiress to the Frisbee fortune. Peter Marano has been in talks to sell the Broadgate West complex for many months, having previously engaged in negotiations with Brookfield, the Canadian property group.
The deal underlines - on the day that the eyes of the world turn to London for the opening of the Olympic Games - the continued interest of overseas investors in London's commercial property market.
The involvement of HSBC Private Bank in the acquisition of Broadgate West is also interesting because it is relatively unusual in deals of this kind.
None of those involved in the deal were available to comment.