He began his career as Deputy Chief Financial Officer at Total in Cameroon in 1990 and then as Financial Auditor at Ernst & Young on various missions in the industrial and financial sectors.

He then moved to the pharmaceutical industry where, from 1996 to 2006, he held positions of increasing responsibility within the finance division of Pfizer France: first in charge of the treasury and internal audit as Director of Treasury, Tax and Audit. In this position, he was responsible in particular for financial risk management for the French subsidiaries of Pfizer and he managed the financial implementation of various restructuring operations (including two mergers, one with Warner-Lambert in 2000 and then Pharmacia in 2003) as well as the implementation of tax and financial optimisation schemes.
Nicolas Fellmann is a graduate of Lyon Graduate School of Management (EM Lyon).