AustralianSuper has entered a joint venture with Brookfield Property Partners LP to acquire a 49-percent stake in 75 State St., a Boston trophy office property that is 98 percent leased.

The transaction values the 31-story tower at $605 million, or $720 per square foot.

Brookfield will retain management and leasing responsibilities at the 841,000-square-foot Financial District property.

“We continue to see healthy demand from investment partners in core, stabilized office property in gateway markets, and took this opportunity to bring AustralianSuper into 75 State Street as part of our ongoing capital recycling initiative,” Ric Clark, CEO of Brookfield Property Group, said in a statement.

Eastdil Secured’s Jeff Scott and Sarah Lagosh represented Brookfield. AustralianSuper was represented by Jim Halliwell and Dan Thornton at Principal Real Estate Investors.

Retirement fund administrator AustralianSuper has $84 billion under management from over two million members, including a $7-billion real estate portfolio.