December 4 2007 Disclosure of Equity Participation Pursuant to the Swiss Stock Exchange Act

Syracuse, New York/Zurich, Switzerland - December 4, 2007 - INFICON Holding AG (SWX Swiss Exchange: IFCN), a leading manufacturer of vacuum instrumentation and process control software for the semiconductor and related industries and other industrial applications, today announced, in line with SWX Swiss Exchange's new disclosure reporting threshold of 3% for equity participations, that according to a notification received via Taryn O'Donoghue from Schroder Investment Management Limited, 31 Gresham Street, London, EC2V 7QA, the company's equity participation in INFICON Holding AG is 99,150 registered shares at CHF 5 par value each as of December 3, 2007. This represents 4.2 % of the voting rights in INFICON Holding AG.