Starting in 1986, he worked in different positions at Rehau Group, a company founded by his father in
Rehau,
Germany. In 2000, Wagner's father transferred control of the company to Wagner and his brother, Veit. As Chairman of the
Supervisory Board of the Rehau group, Wagner led approximately 18,000 employees across 50 countries. In December 2018, following the acquisition of MB Barter & Trading by REHAU, Wagner was confirmed as a member of the new board of directors. On 1 July 2021, Wagner took over the role of vice-chairman of the supervisory board, with his brother Veit taking over his former position as chairman. Wagner is also one of the largest shareholders of the SMH Verlag AG and is member of the supervisory board. He is the founder and the Research Council within the Foundation StrategieDialog21. The StrategieDialog21 (SD21) sees itself as a dialogue platform with a focus on federally-liberal values and derived strategic approaches and impulses for Switzerland. ==Personal life==