Colin Hall - CEO

Colin Hall is the Head of Investments of GBL and the CEO of Sienna Capital.

Previously, he worked at Rhône Group, a private equity firm.

Mr. Hall holds an MBA from the Stanford University Graduate School of Business.

Denis Blank - CIO

Denis Blank is the Chief Investment Officer of Sienna Capital

Before joining Sienna Capital, Denis previously was the Chief Investment Officer at a family office. Previously he worked at a hedge fund focused on Global Emerging Markets.

Denis holds a BA from Southern Methodist University and an MBA from the Stanford University Graduate School of Business.

Johann Dumas - CFO

Johann Dumas is the CIO of Sienna Capital

Before joining Sienna Capital, Johann was the CFO of Quilvest Private Equity.

Johann is chartered accountant in Luxembourg. He holds a Master in Accounting and Finance from the University of Nancy and more recently, he graduated from the Advanced Management Program of INSEAD in 2017.

Figen Eren

Figen joined Sienna Capital in 2020 as Chief Legal Officer.

Prior to joining Sienna Capital, Ms. Eren-Gangloff worked for LVMH and L Real Estate as Director heading Legal, Compliance and Risk Management. She was also Conducting Officer for Compliance and Risk Management approved by the CSSF.

Ruairi Keeley

Ruairi is the Financial Analyst at Sienna Captial.

Mr. Keeley formerly worked as a Credit and Portfolio Analyst at 23 Capital and has previous experience with roles at EQT Partners, 3i Group and GFC Economics.

He holds an MA from the University of St Andrews.

Christoph Ruiner

Christoph Ruiner is the Senior Financial Controller of Sienna Capital.

Before joining Sienna Capital, Christoph previously was Head of Corporate Development at Becker Holding AG & Co. KG as well as Head of Business Controlling at Profine GmbH.

Christoph holds a PhD in Business Administration from Saarland University.


Vincent Noël joined Sienna Capital’s Luxembourg office in 2015 as Financial Accountant/Controller.

Previously, he spent five years working at GDF Suez in Luxembourg.

He holds a BA in Accounting from the Haute École Robert Schuman in Libramont-Chevigny, Belgium.

Antonina Rogler

Antonina Rogler is an Accounts Assistant at Sienna Capital.

Mrs. Rogler worked in Finance and event management sectors as an administrative assistant and receptionist in Moscow and Paris.

Mrs. Rogler graduated in Management at The State University of Management in Moscow. She also holds a degree in Management from the Paris-Dauphine University in Paris.

Victoria Bond

Victoria Bond is Office Manager of the Sienna Capital London office and Executive Assistant to CEO Colin Hall.

Victoria joined Sienna Capital in December 2017 from executive search firm Egon Zehnder, prior to this she assisted the founders of Maverick Advertising & Design in London.

Victoria holds a BSc in Geography from University College London.