Gibson Sotheby’s International Realty acquired New Hampshire-based Madden Group. As part of the deal, the brokerage will open a new office in Portsmouth — its first outside of Massachusetts.

Madden Group’s agents will continue to serve the Seacoast and surrounding markets while former principal owner and managing broker Jennifer Madden will become vice president, New Hampshire for Gibson Sotheby’s.

“Jenn has built a brokerage that reflects many of the values we’ve prioritized as we’ve grown: a boutique culture, close collaboration and a deep commitment to the communities it serves,” said Gibson Sotheby’s founder Larry Rideout. “This builds on a business already active in New Hampshire, where our agents have long served clients from Newburyport and across coastal New England, and Jenn’s team is an exceptional cultural fit.”

In 2025, Gibson Sotheby’s reported $4 billion in sales volume, making it the No. 1 Massachusetts-based real estate firm by sales volume, according to a press release.

“In an industry that has experienced significant change in recent years, our continued growth reflects the stability of our company and the strength of the advisors who choose to build their businesses here,” said Colleen Barry, CEO of Gibson Sotheby’s. “We’re excited to support Jenn and her team through the Sotheby’s International Realty network, connecting their clients to buyers and sellers around the world.”