Newton-based Senior Housing Properties Trust (SHPT) has completed its $1.1 billion acquisition of the Vertex headquarters in Boston’s Seaport District.

SHPT paid $572.8 million for 50 Northern Ave. and $552.6 million for 11 Fan Pier, according to filings at the Suffolk Registry of Deeds. SHPT announced the acquisition in February.

Totaling 1.1 million square feet, the two buildings were developed by The Fallon Co. of Boston as part of its 3 million-square-foot Fan Pier complex. Vertex began moving 1,300 employees from Cambridge to Fan Pier at the beginning of the year.

Last month, Fallon announced that Starbucks, Bright Horizons and a restaurant called Committee have leased 21,450 square feet on the ground floor of 50 Northern Ave.