Cornerstone Real Estate Advisers is purchasing the 20-story building at 99 Summer St. in Boston for about $110.8 million.
The firm, a subsidiary of MassMutual Financial Group, is buying the top-rated office building from Normandy Real Estate Partners, which acquired it in 2006 and has renovated the lobby and other common areas.
The sale comes at a time of increasing activity in Boston’s office market, which is experiencing increases in rent and renewed interest from national and international investors.
Cornerstone, which has offices in the United States, Europe including the United Kingdom, and Asia, is among the world’s largest global real estate managers.
It is also a major investor in the Fan Pier development in the South Boston Innovation District.
The building at 99 Summer has 272,614 square feet of office space and is 93 percent leased. Its exterior features flame finish granite with a red pyramidal roof.
Eastdil Secured served as the broker.