BOSTON—John Hancock plans to build a new 26-story office building in the Back Bay here.

The insurer filed a letter of intent with the Boston Redevelopment Authority on Wednesday to replace the current nine-story building, 140,000-square-foot building at 380 Stuart St. with a new glass office tower. If approved, the Class A building would total 625,000 square feet. John Hancock also owns the 197 Clarendon and 200 Berkeley buildings in the Back Bay.

“For 153 years, John Hancock has called Boston home, and our proposed redevelopment of 380 Stuart Street extends our heritage of significant commitments to the city,” said John Hancock president Craig Bromley in a prepared statement. “The new project embodies bold architecture, continuing John Hancock's tradition of choosing world-class design for its buildings in Boston. We look forward to engaging with our neighbors in our plans for 380 Stuart Street.”

It is expected that the project will create 1,500 construction jobs and provide more than $5 million in what the company terms as linkage funds for affordable housing and job creation to the City of Boston as compared with the present site. The existing 380 Stuart St. building was built in 1924.

The company did not reveal how much of the new building it would occupy once it takes occupancy, but did state that the building would also house other commercial tenants.

“Over the past 10 years, John Hancock has invested more than $300 million to upgrade, enhance and reshape our Boston properties to accommodate business operations,” states Kevin J.E. Adolphe, president and CEO of Manulife Real Estate. “We envision that the building will be not only an important addition to our company's real estate investment portfolio, but will provide us with flexibility in meeting the needs of John Hancock's growing business.” Manulife Real Estate is the global real estate arm of Manulife, operating as John Hancock Real Estate in the U.S. and Manulife Real Estate in all other parts of the world.

The new building will also feature four levels of underground parking and the project is being fully financed by John Hancock and the insurer states that it will have no partners or other third parties in the new building construction venture. If all approvals are secured, the company hopes to break ground on the project in late 2016 and expects to take occupancy of the new property in early 2019.

The architect for the new 380 Stuart St. office building is Skidmore Owings Merrill & CBT and the project manager is Colliers International.