Grégoire has taken part in many financial operations and transactions for major French industrial groups as advisory banker. He has provided advice and support for the development of groups such as Accor, Bouygues, Casino, Engie, Kering, L ‘Oreal, Suez Environnement, and Veolia in France and abroad. He was a member of the economic analysis committee of the French Prime Minister from 2006 to 2010. In that capacity, he co-authored a report on the financing of small and medium-sized enterprises in 2009. He is also a founding member of the Fondapol think-tank where he is vice president of the supervisory board. Emmanuel Macron elevated him to the rank of officer of the Legion of Honour in 2020.
Grégoire obtained an MBA from INSEAD in 1993 and an undergraduate degree from ESSEC Business School in 1988. He also completed undergraduate studies at Centre de Formation à l’Analyse Financière.