A Chelmsford flex portfolio occupied by such tenants as Endeavor Robotics and Thermo Fisher Scientific has been sold for $15.75 million to a Springfield investor.

Chestnut Realty Management acquired 19-21 Alpha Road, which contains 127,000 square feet of flex space in two buildings on 12 acres, from Hudson-based Calare Properties on Aug. 8.

Calare purchased the property for $8.9 million in 2016, when it was 50 percent leased. Under Calare ownership, capital improvements included installation of a new roof and solar panels and expanded parking.

The property is now 100 percent occupied, including space leased to NRG Energy and Krueger Food Laboratories.

“We are incredibly pleased with the outcome at 19-21 Alpha Road, where our investment strategy was executed seamlessly and successfully per our target three-year plan,” Charles Nolfi, managing director at Calare, said in a statement. “Property improvements have attracted premier tenants and generated long-term value for this previously underserved property.”

Cushman & Wakefield’s Dave Pergola, Brian Doherty and Pete Rogers represented Calare in the transaction.