Steffen is a financial markets specialists and a founding partner of Fideres, where he has acted as expert in a number of high-profile financial markets and securities litigation cases in the US, the UK and Europe. His professional expertise includes financial markets and the valuation of financial transactions and securities, including equity and debt instruments, derivatives and structured products. Steffen has provided expert testimony on market efficiency and damages quantum and the valuation and risk of securities and derivatives.

Prior to Fideres, Steffen was a director at the Royal Bank of Scotland, working within the Exotic Credit Derivates and Structured Capital Solutions team. Before joining RBS he worked in a similar role to Deutsche Bank.

Steffen holds an MSc-level degree in Mathematics (Diplom Mathematik) from the University of Erlangen (Germany), the Certificate of Advanced Studies in Mathematics from the University if Cambridge (UK) and an MSc in Financial Engineering and Quantitative Analysis from the ICMA Centre at the University of Reading (UK).