He worked as a turn-around management consultant with the Investment Management & Consulting Group (IMCG) and with the International Corporate Finance Group of
ABN AMRO Bank. Thielen was a partner and shareholder of RWP Corporate Finance advisors, which was later acquired by Investec group. He was also general manager of his family owned fashion retail group. He is chairman and founder of Waterland Private Equity Investments, an independent private equity group which focuses its investments on
Austria,
Belgium,
Denmark,
Germany,
Ireland, the
Netherlands,
Poland, the
United Kingdom and
Switzerland. Waterland has been involved in about 500 transactions in 54 industries in 18 countries with an equity base of around €6 billion. The company owned
Intertrust Group, until it sold that firm in 2012 for an estimated €400 million. Waterland has ranked in the top 3 of best performing private equity houses globally for 8 years in a row. He was co-founding partner of Elbrus Capital, a Russia-based private equity group. Its equity base is around $1 billion. == Other positions==