Westfield Corp., which operates upscale shopping malls in Annapolis and in dozens of other U.S. cities and in Britain, agreed to be acquired for nearly $16 billion by French commercial real estate giant Unibail-Rodamco, the companies said Tuesday.

The deal underlined how even operators of marquee malls are not immune from the seismic shift occurring in retail, where consumers worldwide are increasingly moving more of their shopping to online sites such as Amazon.com and away from physical stores in malls and elsewhere.

Westfield, based in Australia, owns 35 malls, including Westfield Annapolis, Westfield Montgomery and Westfield Wheaton in Maryland.

Unibail-Rodamco operates 69 shopping centers in major European cities including Paris, Madrid, Stockholm, Amsterdam and Munich, Germany, and it’s developing malls in Brussels and Hamburg, Germany.

The new company will be based in Paris and Amsterdam, with regional headquarters in Los Angeles and London.

“The industry is under severe pressure from internet selling and particularly Amazon,” said John Colley, a professor at Britain’s Warwick Business School, in an email. “Clearly there are significant savings as the new enterprise will need only one head office, board, systems and functional management.”

Hundreds of bricks-and-mortar stores — especially department stores, apparel-heavy outlets and sporting goods stores — already have closed in the United States in the last year as foot traffic has fallen. That has put pressure on mall operators to fill the vacancies, especially for outlets that serve as anchor stores.

That pressure had resulted in Westfield’s shares falling about 9 percent this year before the merger announcement, and it has sparked the consolidation trend among mall operators seeking heft and cost efficiencies.

The proposed merger “creates a strong and attractive platform for future growth,” Unibail-Rodamco Chief Executive Christophe Cuvillier said in a statement.

The deal also is an opportunity for billionaire Frank Lowy, Westfield’s 87-year-old chairman, to turn over his company in order to cash out a major part of his family’s 9.5 percent ownership in Westfield.

In Anne Arundel County, Westfield Annapolis is one of three major malls. Arundel Mills in Hanover is owned by Simon Property Group. Marley Station mall has changed hands several times since enterting bankruptcy, most recently in November 2016 to LNR Properties.

Westfield bought the Annapolis property in 1994 and spent the next decade on renovations and expansions. It added Nordstrom, Lord & Taylor, Borders and renovated the multiplex theater. In 2007, it opened a a new 240,000-square-foot wing with a mix of 33 new stores.

But just as market changes have put pressures on the industry, they have impacted Westfield Annapolis. Borders closed years ago, The Gap is gone and in November, the parent company of the Lord & Taylor department store notified state officials that it would close the store in April and lay off more than 100 employees.

Starbucks is closing a number of its Teavana locations, including the one at Westfield Annapolis.

The worldwide consolidation trend indicates “the shopping center industry is definitely coming to a different point in its maturity,” said David Gorelick, head of retail in the Americas for real estate brokerage Cushman & Wakefield.

“Institutions that are best in class are looking to acquire other shopping centers in different regions and leveraging their capabilities,” Gorelick said.

Unibail-Rodamco agreed to pay $7.55 in cash and stock for each share of Westfield. The deal was approved by both companies’ directors but remains subject to approval by the firms’ shareholders. The merger is expected to close in the first half of next year.

Westfield began in 1959 when Lowy and his partner John Saunders opened a shopping center in Sydney, Australia. The company’s Australian and New Zealand holdings were spun off into a separate company in 2014.

Lowy, a Holocaust survivor from Czechoslovakia, has a net worth of $5.9 billion, according to Forbes. He served as Westfield’s chief executive for more than 50 years before becoming nonexecutive chairman in 2011. He was knighted by Queen Elizabeth II this month for his contributions to the United Kingdom’s economy and for his philanthropy.

Lowy will retire as Westfield’s chairman after the merger, and his sons Peter and Steven will step down as Westfield’s co-chief executives.

Frank Lowy will become chairman of a newly created advisory board and Peter Lowy, who is based in Los Angeles, will be appointed to the company’s ruling supervisory board.