

Leadership Team
Our founders bring investment expertise, hands-on operational know-how and experience advising many of the world’s largest family offices and long-term investors

Sean Costello
Managing Partner
Sean has more than 30 years of experience in investment banking, equity research, and UHNW/ Global Family Office private banking across the US and almost two decades in Europe. He has worked in senior roles at firms including Morgan Stanley, Lehman Brothers, and Barclays. Sean's clients include some of the largest family offices, sovereign wealth funds, and similar long-term institutional investors.
Sean is an honors graduate of the University of Pennsylvania and holds an MBA from Duke University’s Fuqua School of Business.
Sean is a US, UK, and EU (Irish) Citizen

Michael Kurdziel
Managing Partner
Michael brings experience working with family offices in private equity and venture capital. He was a co-founder of DealerTrack (NASDAQ: TRAK), a venture capital-backed technology firm that secured more than $75mm in financing before going public in 2005. He has led private equity investing for several family offices and has experience sourcing and managing venture capital investments. Over the course of his banking and private equity career, he has led numerous equity and debt transactions totaling more than $1 billion in value. Michael's areas of expertise also include structured credit and debt placement. Michael serves on the board of several private companies and non-profits.
He earned his BA from Trinity College with high honors and an MBA from Duke University’s Fuqua School of Business

Daniel Costello
Managing Partner
Daniel most recently worked for 5 years as SVP of Global M&A and Strategy at News Corp in NYC, after working for News Corp in London. Under his leadership, News Corp completed over $2.5 billion of investments including the acquisitions of Move.com ($1B, US), Harlequin ($400M, CA), Unruly ($200M, UK), Wireless Group/Sports Talk ($200M, UK), Storyful ($20M, Ireland), as well as additional acquisitions across multiple technology and media sectors in India, Thailand, Australia and Europe. Daniel worked for over a decade as a journalist for The Wall Street Journal and the Los Angeles Times, covering economics, healthcare, and politics.
Daniel earned his BA from the University of Pennsylvania in economics and Japanese, and an MBA from Duke University’s Fuqua School of Business

Karen Mitchell
Chief of Staff
Karen Mitchell serves as Chief of Staff for Participant Capital, based in the firm's London office, where she manages client relationships across Participant's global network of family offices, sovereign wealth funds, and institutional investors. Her work spans the full deal lifecycle — from initial introduction through diligence, allocation, and ongoing reporting — and she's frequently the primary point of contact for institutional partners engaging with the platform, providing the continuity that matters in relationships built over years rather than single transactions.
She also leads planning and execution for Participant's investor conferences and private client gatherings, overseeing events that bring the firm's global network together in person.

Jay Liebowitz
Managing Director, Debt Capital Advisory
Jay leads the firm's debt capital advisory practice for Participant. With over 25 years of experience, he has been involved in billions of dollars of transactions across healthcare, pharmaceuticals, consumer wellness, and animal care. Before joining Participant, Jay was a managing director at Post Advisory and a principal at Blackstone Credit, focusing on high-yield, distressed, and mezzanine investments. He also served as an associate at Black Canyon and started his career as a financial analyst at Credit Suisse First Boston.
Jay graduated summa cum laude from the University of Pennsylvania's Wharton School and is a board member of Access Youth Academy, a nonprofit supporting urban youth.
Participant Capital LLC (US) offers securities through Hollister Associates, LLC, member FINRA/SIPC. Participant Capital LLC and Hollister Associates, LLC are not affiliated entities. Check the background of investment professionals on FINRA's BrokerCheck.
Participant Capital LTD (UK) is an Appointed Representative of Kroll Securities Limited, which is authorised and regulated by the Financial Conduct Authority.




