John Hancock is moving back to the Back Bay.
The insurance company said Tuesday that it will relocate more than 1,000 employees from its headquarters in the Seaport District to two properties it owns in the Back Bay, including the longtime Hancock building on Berkeley Street with its distinctive weather beacon.
The move represents an unusual development for the booming Seaport District, which has been gaining, not losing, big employers. When Hancock moved its headquarters to the Seaport in 2005, it was one of the first major companies to set down stakes in the neighborhood, which was at the time mostly a sea of parking lots.
Since then, an entire business district has grown up around Hancock’s Congress Street location, and the area is now among the most expensive — and crowded — addresses in Boston.
Hancock also maintained a presence in the Back Bay, where it has about 2,200 employees, though it is no longer affiliated with the city’s tallest building, the glass skyscraper that bore the insurer’s name for decades. Today, the former Hancock Tower is known as 200 Clarendon.
In a memo to employees on Tuesday, Hancock’s chief executive, Marianne Harrison, said bringing all of the company’s Boston employees together at one location in the Back Bay would improve the corporate culture and customer service.
“Working together as a team is crucial to our success,” said Harrison, who was appointed to the top job in October.
A Hancock spokeswoman said the relocation will not be accompanied by a cut in the workforce. The company has a total of 1.2 million square feet of office space at 200 Berkeley St. and 197 Clarendon St., enough to accommodate the workers from the Seaport.
Hancock, which traces its founding to 1862, has also received the city’s approval to build a 26-story tower on Stuart Street near its two Back Bay properties.
Several Boston-area real estate professionals said that if Hancock is rooting itself in the Back Bay, the proposed building would provide the logical next place to grow. In her memo, Harrison told employees that Hancock is continuing to work on plans for the tower, but did not elaborate.
Harrison also noted that the move enables Hancock to save on real estate costs. The company hasn’t decided whether it will sell or lease out the 465,000-square-foot building in the Seaport that it’s leaving. Hancock’s parent, Manulife Financial Corp., owns the 14-story Congress Street building, which sits on land leased from the Massachusetts Port Authority, and has the right to sell or lease out the structure. The ground lease lasts through 2096.
Returning to the Back Bay makes sense on two levels, said Brendan Carroll, director of intelligence at the real estate firm Perry Brokerage: It allows Hancock to put all of its Boston employees in one place and lets the company sell or lease a valuable building in a hot real estate market.
A number of blue-chip employers, including Vertex Pharmaceuticals, Boston Consulting Group, and Akamai Technologies, have consolidated Boston-area operations under one roof or are in the process of doing so, Carroll said — despite technology that makes it easier to work remotely.
“There’s value in having your workforce in one location,” Carroll said. “You’re seeing companies really double down to make that happen.”
As for the Congress Street building that Hancock is leaving, Carroll said the company should have no problem finding takers, because many larger companies — such as Amazon — are looking to expand in the Seaport.
“That will not remain a vacant building for very long,” Carroll said.
The Back Bay has also been experiencing a wave of development and corporate expansions lately, since several prominent employers decamped for the Financial District. In addition to building the new Hancock tower, Boston Properties is planning to erect a massive complex above the Massachusetts Bay Transportation Authority’s Back Bay Station, between Clarendon and Dartmouth streets.
Several blocks west, Boston Properties recently opened a 17-story building on Boylston Street that’s part of the Prudential complex.
The developer also owns the former Hancock Tower, at 200 Clarendon St., and has largely refilled empty offices there after several big tenants, including John Hancock, moved out over the past decade or so.
Meanwhile, DraftKings and WeWork have signed sizable leases for Boylston Street properties in recent months, while the online retailer Wayfair is close to finalizing plans for an enormous expansion.
Hancock’s homecoming is a huge statement for the neighborhood, said Meg Mainzer-Cohen, president of the Back Bay Association, a business group.
“I think it’s fantastic news,” she said. “They were part of the Back Bay’s DNA. To have them return, well, it’s huge.”