Shopping centre giant Westfield is to be taken over by Unibail Rodamco in a $24.7 billion (£18.5 billion) deal.
The combination of the two firms will see the creation of a property titan worth $72.2 billion (£54 billion) spanning countries including Australia, Britain, France, Spain and the United States.
The deal will see Paris-based Unibail pay shareholders in Australia's Westfield Corporation - which has giant malls in London's White City and Stratford - $7.55 a share at a 17.8% premium.
Unibail chief executive Christophe Cuvillier said: "The acquisition of Westfield is a natural extension of Unibail-Rodamco's strategy of concentration, differentiation and innovation.
"It adds a number of new attractive retail markets in London and the wealthiest catchment areas in the United States. It provides a unique platform of superior quality shopping destinations supported by experienced professionals of both Unibail-Rodamco and Westfield."
The acquisition is expected to result in $100 million in cost savings per year across the 104-property group, and the firms have committed to expanding the Westfield brand "flagship shopping destinations".
It comes amid consolidation in the sector.
Last week shopping centre owner Hammerson agreed an all share takeover of rival Intu in a £3.4 billion deal that will create Britain's biggest property company.
The likes of Intu-owned Lakeside and the Bullring in Birmingham, controlled by Hammerson, will come under one roof, forming a £21 billion giant.
Frank Lowy, Westfield chairman, said: "The transaction announced today is the culmination of the strategic journey Westfield has been on since its 2014 restructure.
"We see this transaction as highly compelling for Westfield's securityholders and Unibail-Rodamco's shareholders alike. Unibail-Rodamco's track record makes it the natural home for the legacy of Westfield's brand and business."