BellCornerstone Announces Ownership Transition and Next-Generation Leadership

Manlius, NY — January 1, 2026 — BellCornerstone, a nationally recognized commercial real estate brokerage headquartered in Manlius, New York, announced today the completion of an internal ownership transition that positions the firm for its next phase of growth.

Longtime owner Mark Bethmann has sold his remaining ownership interest in the firm to existing partners Aidan Cleghorn and Brian Rossi, effective January 1, 2026.

Bethmann will remain with BellCornerstone as President Emeritus and Director of Tenant Representation Services, where he will continue advising clients and supporting the firm’s strategic initiatives. A widely respected industry veteran with more than 30 years of experience, Bethmann has helped companies navigate complex real estate decisions across the country and was an early pioneer of tenant representation services as a specialized advisory discipline within the brokerage industry.

“Aidan and Brian have been exceptional partners and leaders within the firm,” said Bethmann. “This transition reflects the strength of our team and the opportunities ahead for BellCornerstone as we continue to expand our impact nationally.”

Under the new leadership structure, Aidan Cleghorn will serve as Managing Broker and Principal, while Brian Rossi will assume the role of Chief Executive Officer.

Cleghorn, a seven-time CoStar Power Broker award recipient, has completed numerous landmark transactions across the country and is widely recognized for advising companies on large, operationally significant real estate decisions.

Rossi is an accomplished entrepreneur who has founded, grown, and successfully exited multiple businesses, bringing a strategic and operational perspective to BellCornerstone’s continued expansion.

“Mark built an extraordinary platform and culture at BellCornerstone,” said Rossi. “We are honored to continue working alongside him and are excited to build on that foundation as we expand the firm’s capabilities and serve clients facing increasingly complex real estate decisions.”

BellCornerstone has developed a national reputation for advising corporations on complex real estate challenges involving large and operationally significant properties. Over the past decade, the firm has facilitated the sale of more than 1,000 newspaper and printing facilities across North America and has advised numerous regional and national companies in optimizing and repositioning their real estate portfolios.

Looking ahead, BellCornerstone plans to accelerate its growth through strategic acquisitions, expanded advisory services, and targeted industry verticals, while continuing to provide corporate clients with disciplined, creative solutions to complex real estate challenges.

About BellCornerstone

BellCornerstone is a nationally recognized commercial real estate brokerage headquartered in Manlius, New York. The firm specializes in advising corporations on complex real estate transactions involving large, operationally significant properties throughout North America.