A landmark office tower that demonstrated the staying power of Boston’s Financial District following the departure of law firm Goodwin for the Seaport has a new set of owners.

Allianz Real Estate, the Massachusetts Pension Reserves Investment Management (PRIM) and Beacon Capital Partners this week acquired the 1.2-million-square-foot Exchange Place tower at 53 State St. for $845 million from UBS.

Vacancies at Exchange Place rose above 300,000 square feet following Goodwin’s departure for the Fallon Co.’s newly completed 100 Northern Ave. office building in 2016. A leasing program by Cushman & Wakefield secured new tenants including The Boston Globe, Rubin and Rudman, Press Gainey Assoc., Aon and Experian Information Solutions. The property is now 93 percent leased.

UBS, which paid $610 million for the property in 2011, also added a new conference center, Squeeze Cafe and a 7,000-square-foot terrace on the 12th floor.

The property includes the historic Boston Stock Exchange Building from 1891 and the adjacent 40-story glass tower built in 1985. It includes a 7-story, glass-enclosed atrium and an outdoor arcade with seating areas along Congress Street.

A spokesman for PRIM could not say what share of the purchase price the pension fund was responsible for, but Michael Trotsky, executive director and chief investment officer at PRIM, said, “Our real estate portfolio includes some of the top office buildings in the U.S., and this investment is consistent with our overall strategy to generate strong returns from Class A properties.”

PRIM’s headquarters are across the street from Exchange Place at 84 State St.

“53 State St. is a high quality acquisition and another example of PRIM’s strategy of investing in excellent properties with potential for long-term gain,” said Treasurer Deborah Goldberg, who chairs the PRIM board. “Our partnership with Beacon and Allianz continues our collaboration with exceptional partners and we are pleased to be working with them as we move forward.”

PRIM oversees roughly $70 billion is assets for the retirement of teachers and many state and municipal employees.

Material from the State House News Service was included in this report.