[4] At the end of the 1950s he met the advertisers Karl Gerstner and Markus Kutter [de] and became their partner in 1962.
After Gerstner and Kutter retired in 1975, Gredinger took over their shares and expanded the agency into a European network with up to 20 branches.
[5] Gredinger supported his artist friends such as Dieter Roth, André Thomkins and Donald Judd.
Gredinger was elected honorary member for Germany by the Art Directors Club of New York in 1992.
[6] Gredinger was brought to ETH Zurich in 1999 by the then guest lecturer Valerio Olgiati as a fictitious client, for whom one of the residential buildings was designed by Raphael Zuber.