His combination of knowledge, eye for quality, charm, humor, looks,[3] and discretion took him to the top of the art world by his mid 30s[4] (Skis with Valentino, dines with Audrey Hepburn and Elizabeth Taylor ... lives on the Concorde.
[6] A memorial service was held at the Church of St. Peter in Zurich [7] and subsequently at The Solomon R. Guggenheim Museum in New York City on 18 November 1993, with speakers Patricia Phelps de Cisneros, Thomas Krens, William H. Luers, Ernst Beyeler, Robert Wilson (director), Bob Colacello, Bianca Jagger and artists Ross Bleckner, Francesco Clemente, and Eric Fischl.
[10] From his villa by Otto Rudolf Salvisberg[11] on the hill of Zurich, his chalet in Gstaad or his apartment at the Pierre in New York, Ammann dealt mainly in paintings and sculpture by twentieth century artists including Francis Bacon, Balthus, Max Beckmann, Constantin Brâncuși, Georges Braque, Alexander Calder, Alberto Giacometti, Wassily Kandinsky, Ernst Ludwig Kirchner, Paul Klee, Willem de Kooning, Fernand Léger, Henri Matisse, Joan Miró, Barnett Newman, Pablo Picasso and Mark Rothko.
The press noted "his presence in the worlds salesrooms created a mood of optimism, whatever the market conditions, and his enthusiastic bids for paintings by Cy Twombly and Andy Warhol were driven by genuine passion as much as potential profit".
The art world agreed on Thomas Ammann's collection of works of the second half of the twentieth century to be amongst the finest in existence,[17] with unparalleled[21] workgroups of artists such as Andy Warhol, Cy Twombly, Brice Marden, Robert Ryman, Sigmar Polke, Eric Fischl, Francesco Clemente and Neil Jenney.
Ammann convinced artist friends from Jasper Johns to Cy Twombly to donate works to the auction he co-hosted with Patricia Buckley, the proceeds of which went to the supportive care programme of St. Vincent's Hospital and Medical Center of New York.
[26] It was in 1977 that Ammann envisioned a catalogue raisonné[27] of all of Andy Warhol's paintings, sculptures and drawings, and with the artist's consent, started the vast undertaking of assembling the material needed for such a project to finally create a comprehensive, scholarly and authoritative publication.