Sachverständigenrat zur Begutachtung der gesamtwirtschaftlichen Entwicklung
Giersch was succeeded by Horst Siebert (1938–2009) in 1989. Numerous economic sea changes also took place during his period in office: communist economies collapsed, the two Germanys were reunited, China became a world economic power, information technology emerged, and reforms of the labor market and social security systems became topical, as did the sustainable use of environmental resources as well. During his period in office, he was, like Herbert Giersch before, a member of the German Council of Economic Experts. Further, he defined the Institute's public image by often appearing on television and by publishing numerous articles and monographs on topical economic issues. Under his leadership, the Institute became more involved in environmental and resource economics, and international financial market economics. Siebert served as the president of the Institute until 2003, when he was given emeritus status.