"Rodamco's strategy of concentration, differentiation and innovation", Unibail-Rodamco CEO Christophe Cuvillier said in the statement. The company also is developing malls in Brussels and in Hamburg, Germany.
Unibail-Rodamco has been selling smaller and less dominant assets in its European retail portfolio and reinvesting the proceeds in its development pipeline, which includes larger malls that are expected to be more resilient to the growth of online shopping.
The Lowy family, which owns 9.0 percent of Westfield, said they would rather be investors than executives after putting in a combined 145 years at the company, which has stakes in 18 suburban US shopping centers, three of which it wholly owns.
Unibail will acquire Westfield for $7.55 per share, a 18 percent premium over Westfield's closing price on Monday.
Lowy said it made sense to sell because Unibail offered a "very good price", but acknowledged that the sale partly reflected global consolidation and the pressure on retailers. Westfield, which started off in Sydney in the 1950s, is known for its 35 upscale shopping centers in major metropolitan areas, particularly in the USA and Britain.
Not yet. Unibail-Rodamco's value fell as much as 4.1% on news of the deal.
The new Nordstrom store at Westfield UTC mall. Unibail-Rodamco shares have fallen 1.2 percent.
Unibail Rodamco is the largest commercial real estate company in Europe and will own 104 properties across the world when the acquisition is complete, reportedly resulting in cost savings of $100 million a year.
Westfield Group spun off its Australian and New Zealand operations in 2013 and reorganized its Northern Hemisphere properties as Westfield Corp.in 2014.
Frank Lowy, Westfield's chairman, said "the transaction announced today is the culmination of the strategic journey Westfield has been on since its 2014 restructure". "Steven Lowy serves on Scentre's board", he continues.
Speaking from Milan, Lowy said it was a day of mixed emotion, but was certain it was appropriate to do the deal now.
He was knighted last week in a ceremony at Windsor Castle in recognition of his contribution to the British economy.