The Im Obersteg Foundation was founded 1992 by Doris Im Obersteg-Lerch (1931–2015) and is based in Basel since 2004. The foundation’s capital, the important classical modern collection of Karl and Jürg Im Obersteg, has been housed in the Kunstmuseum Basel ever since. The collection consists of about 220 paintings, sculptures and works on paper as well as a comprehensive archive of artist letters. The aim of the foundation is to preserve the collection and make it accessible to the public through exhibitions and publications. The two exhibition rooms of the Im Obersteg Foundation on the intermediate floor of the Hauptbau host temporary exhibitions on selected themes from the Im Obersteg collection, supplemented by works from the Kunstmuseum. Every five to eight years, a representative overview exhibition of the collection is also shown at the Kunstmuseum.
For the Kunstmuseum Basel, this permanent loan is an exceptionally valuable addition. World-famous masterpieces such as The Jew in Green, The Jew in Red, and The Jew in Black and White by Marc Chagall (1887–1985), as well as Pablo Picasso's (1881–1973) Buveuse d'absinthe – a major work from the beginning of his Blue Period – complement the museum's collection perfectly. A group of 30 works by Alexej von Jawlensky (1864–1941) from all creative periods, unique in Switzerland, and an ensemble of paintings by Chaïm Soutine (1893–1943) set new accents in Basel.
Basel-based freight forwarder and art connoisseur Karl Im Obersteg (1883–1969) and his son Jürg (1914–1983) collected international 20th-century art over a period of around 70 years. There was never a specific concept behind the collection. Rather, friendships with artists, especially Jawlensky, and a preference for expressive figurative painting influenced the respective purchases. Not only the expressiveness of color is a constant leitmotif, but also the haunting, melancholic view of human existence.