French property giant Unibail-Rodamco is to buy Australia's Westfield shopping mall operator in a deal to create "a global property leader", the two groups said in a statement.
The deal, which values Westfield at US$24.7 billion, would "create the world's premier developer and operator of flagship shopping destinations", they said.
Tuesday's announcement comes as mall operators embark on a consolidation drive as they face increasingly tough competition from online shopping sites such as Amazon, which this month launched in Australia.
Westfield's share price is down about 10 percent in 2018.
"The acquisition of Westfield is a natural extension of Unibail-Rodamco?s strategy of concentration, differentiation and innovation," Christophe Cuvillier, chief executive officer of Unibail-Rodamco, said.
"It adds a number of new attractive retail markets in London and the wealthiest catchment areas in the United States.
"We believe that this transaction represents a compelling opportunity for both companies to realise benefits not available to each company on a standalone basis, and creates a strong and attractive platform for future growth."
The statement said the proposal had been "unanimously recommended by Westfield?s board of directors and Unibail-Rodamco?s supervisory board".
Unibail-Rodamco is Europe's largest commercial landlord and the purchase comes as it offloads smaller assets in Europe to focus on bigger shopping centres, which are likely to be better suited to fending off the march of e-commerce giants.
-- Bloomberg News contributed to this story --
© 2017 AFP