Insurer Independence Blue Cross has paid $360 million for the 45-story office tower at 1901 Market St. that it has long occupied as a tenant.

The purchase was an investment “in the growth and efficiency of our organization,” IBC chief financial officer Gregory E. Deavens said in a news release Tuesday.

The sale price works out to about $450 a square foot for the 801,000-square-foot office tower, among the highest valuations on record for a non-medical office building in Center City.

Independence Blue Cross has leased the Market Street tower since it was built as the health insurer’s headquarters in the late 1980s. Seller Piedmont Office Realty Trust of Atlanta acquired the property in 2003.

The insurer and its subsidiary businesses also occupy about half of the 457,000-square-foot property across the street at 1900 Market St., formerly known as the Stock Exchange building.

The company posted $16.3 billion of total revenue in 2018, according to its most recently filed annual report. Its surplus was $2.9 billion.

Piedmont was represented in the deal by brokers Robert Fahey, Jerry Kranzel, Erin Hannan and Jack Corcoran of commercial real estate firm CBRE.