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A sovereign institutional investor has bought a 45-percent stake in the Vertex Pharmaceuticals headquarters on Boston’s Fan Pier for $261 million.

Newton-based Senior Housing Properties Trust, which acquired the buildings at 11 Fan Pier and 50 Northern Ave. in 2014 for $1.1 billion, said Monday it has formed a joint venture with the unidentified passive investor. The deal is based upon a valuation of $1.2 billion with $620 million in debt.

Vertex leases 95 percent of the two 15-story buildings developed by The Fallon Co. of Boston.

SHPT will use the proceeds to repay a part of its revolving credit facility, the company said in a press release.

Eastdil Secured represented SHPT and Sullivan & Worcester LLP provided legal counsel.

Investor Buys $261M Stake In Vertex Headquarters

by Steve Adams time to read: <1 min