Stephen Siderow is the founder and managing principal of Siderofsky Strategic Advisors LLC, a boutique advisory firm that partners with high-growth companies across a range of industries, with particular expertise in financial services, fintech, and alternative investment management. Drawing on over three decades of global business leadership, Stephen provides strategic guidance to early-stage and rapidly scaling businesses, helping them navigate growth opportunities and operational complexities with seasoned insight.

Currently, Stephen advises several innovative companies, including Allposit Inc., which delivers integrated digital platforms to the wealth management sector; NewVest, a pioneer in passive index investing for private markets; along with a number of other early-stage ventures. His previous advisory work includes a role as Senior Advisor to Crayhill Capital, a New York-based private credit investment firm focused on asset-based structured finance.

In addition to his professional work, Stephen is deeply engaged in the nonprofit sector. He serves on the boards of multiple organizations, including iTrek, which connects future leaders in law, business, technology, and public policy to Israel; CLAL—The National Jewish Center for Learning and Leadership, a hub for Jewish thought leadership and innovation; the Hertzberg Palliative Care Institute at Mount Sinai Hospital, which is advancing palliative care education and services; and Ars Nova, a prominent incubator for emerging artists in New York City. Stephen was also a longtime board member and Vice Chairman of the Birthright Israel Foundation, which provides educational trips to Israel for young Jewish adults.

Prior to founding Siderofsky Strategic Advisors, Stephen was President and Co-Founder of BlueMountain Capital Management, an alternative investment firm he launched with Andrew Feldstein in 2003. Under their leadership, the firm grew to oversee $23 billion in assets, employed over 300 professionals, and operated offices in New York, London, and Tokyo. BlueMountain developed and managed a broad suite of investment strategies—including long/short and structured credit, private capital, CLOs, and special situations—through both commingled and customized funds. Stephen was instrumental in structuring the firm’s minority interest sales to Affiliated Managers Group (AMG) in 2005 and 2012, as well as in the full acquisition of the firm by Assured Guaranty in 2019. During his tenure, he oversaw core business functions including strategic planning, investor relations, legal, compliance, finance, and human resources. He also served on the firm’s key leadership committees, including its Management, Investment, Compliance, and Risk Committees.

Following his time at BlueMountain, Stephen spent two years as a Senior Strategist at Millennium Management, a major multi-manager hedge fund based in New York. Earlier in his career, he was a Senior Consultant at McKinsey & Company, working with top-tier financial institutions across global hubs such as New York, London, Zurich, and Tel Aviv on strategic growth initiatives. He began his professional journey as a corporate attorney at Cleary Gottlieb and served as a law clerk to Judge Jacob Mishler of the U.S. District Court for the Eastern District of New York.

Stephen earned his J.D. with honors from Harvard Law School and graduated magna cum laude with a B.A. in Philosophy from Amherst College. He was also awarded both a Fulbright and a Sheldon Fellowship to pursue studies at Tel Aviv University in Israel.