Our Team

Michael Castor, MD
Portfolio Manager

Michael founded Sio in 2006 and has served as the portfolio manager since the firm’s inception. Prior to this, Michael worked at Bernstein Investment Research and Management from 2001 to 2006 as the firm’s healthcare analyst and as the healthcare sector leader. Prior to Bernstein, Michael worked in the investment banking/equity capital markets division of JP Morgan where he focused on biotechnology and healthcare equity offerings.

Before entering finance, Michael spent three years in clinical medicine. He completed his surgery internship at Indiana University Medical Center followed by two years of surgery and otolaryngology residency at Columbia Presbyterian Medical Center in New York. Michael earned his MD from The Ohio State University College of Medicine where he graduated summa cum laude. He earned his undergraduate degree in biomedical engineering from Tulane University where he graduated summa cum laude with departmental honors.

Albert Vigneau

Albert is the CFO at Sio. He has over 17 years of experience in hedge fund financial roles, both acting as CFO and working in various accounting functions. Before Sio, Al served as the CFO for Tiger Europe Management, LLC. Prior to that, Al worked as a Senior Hedge Fund Accountant at Moore Capital Management and as a Controller at Tiger Global Management, LLC. Al has also worked in hedge fund administration, having been a Senior Hedge Fund Accountant at BNY Alternative Investment Services. Al graduated from Northeastern University with a Bachelors of Science in Business Administration with dual concentrations in Accounting and Finance.

Vladimir Vasilyev
Research Analyst

Vladimir is a research analyst covering healthcare distributors, services and information technology. Prior to joining Sio, Vladimir worked as an equity derivatives trader at Access Securities. He earned his MBA with concentrations in Accounting, Finance, and Management from Columbia Business School in 2008, where he was placed on the Dean’s list. He earned his undergraduate degree in Economics from the University of Alaska Anchorage. Vladimir is a CFA charterholder.

Usman Hassan
Research Analyst

Usman is a research analyst covering medical technology and select healthcare services. Before joining Sio, Usman worked for four years as a management consultant at Oliver Wyman, advising clients in the manufacturing and retail sectors on strategy and operations improvement projects. Usman graduated magna cum laude from The Wharton School in 2006 with a Bachelors in Economics and a concentration in Finance, as well as a degree in Computer Science from the University of Pennsylvania.

Logan Suriano
Research Analyst

Logan is a research analyst covering biotechnology and specialty pharmaceuticals. Prior to joining Sio, Logan worked for four years as a sell-side research analyst covering biotechnology (Merrill Lynch) and clean energy (First Berlin Equity Research). Logan graduated from the University of North Carolina with a dual undergraduate degree in Mathematics and Chemistry. He earned his MBA from the Yale School of Management in 2012.

Mansi Sanghvi
Research Analyst

Mansi is a research analyst covering services. Prior to joining Sio, Mansi worked in the Private Banking Group at ICICI Bank, focusing on marketing strategy. Mansi earned her MBA at the Indian School of Business (ISB) with majors in Strategy and Finance. She has an undergraduate degree in Electrical Engineering from Mumbai University.

Willis Hu, CFA
Research Analyst

Willis is a research analyst covering multiple healthcare segments with primary focus on specialty pharmaceuticals. Prior to the current position, Willis worked as the head of operations at Sio. Willis earned his Master of Science in Finance degree from Fordham University. He earned his undergraduate degree in Finance from William Paterson University where he graduated summa cum laude. Willis is a CFA charter holder.