Isaac Zion is a managing principal of real estate investment firm Acram Group, which he formed in early 2021 with David Taylor and Matthew Cassin as the successor company to JMC Holdings, the firm founded by Taylor and Cassin.

Prior to Acram, Zion was co-CIO at SL Green Realty Corporation. Zion joined SL Green in 2007, and was made co-CIO along with David Schonbraun in 2011. He was previously the co-head of the company's investment group and head of the suburban portfolio.

Prior to SL Green, Zion was a managing director of Tishman Speyer where he was responsible for acquisitions and dispositions. When he first joined Tishman in 2002, Zion headed marketing and leasing operations for the firm. Before Tishman, Zion was a director at CBRE (then Insignia/ESG), focusing on tenant representation on large leasing deals.

Over the course of his career, Zion has played a role in over $25 billion of investment and leasing transactions.

Zion is a member of the Real Estate Board of New York (REBNY) and the Urban Land Institute.