A massive office tenant is expanding to more than a half-million SF in Boston’s Atlantic Wharf tower.

Wellington Management signed a 524K SF, 10-year lease extension at 280 Congress St., Boston Properties and Norges Bank Investment Management announced Wednesday evening. The investment management firm will add 66K SF beginning next year and will occupy 22 floors of the 31-story tower through 2036.

“Since day one, Wellington has been an extraordinary partner and supporter in our commitment to sustainable innovation and bringing diverse public programming and access to the waterfront,” BXP Executive Vice President of the Boston Region Bryan Koop said in a release.

Wellington has been headquartered at the 790K SF tower since it opened in 2011. The BXP and Norges Bank joint venture also owns 100 Federal St. in Boston's Financial District and the 601 Lexington Ave. and 7 Times Square office towers in New York City.

Atlantic Wharf sits across South Boston's Fort Point Channel waterfront and is two blocks north of South Station. BXP in 2018 installed AquaFence portable storm barriers, which at least a dozen waterfront buildings have added since then, the REIT said in a statement. Atlantic Wharf also touts LEED Double-Platinum certification, a rooftop rain harvesting system, and four rooftop beehives, which produce honey gifted to tenants and the community.

Wellington’s lease at the tower appears to be the year’s second-largest office commitment, behind Amazon’s 630K SF full-building lease with WS Development in the Seaport.

Boston office leasing activity paused in August, but sublease activity declined and the market retained a healthy active tenant roster, according to a new CBRE report. The historic Boston office market woes of last winter appeared on the upswing in Q2 according to market reports, and at least four leases and subleases exceeding 100K SF have been signed over the summer.