October 12 2005 Disclosure of Equity Participations Pursuant to the Swiss Stock Exchange Act

Syracuse, New York/Zurich, Switzerland - October 12, 2005 - 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 that according to a notification received from Zürcher Kantonalbank, Zurich, the equity participation of Zürcher Kantonalbank in INFICON Holding AG is now 325,462 shares with a par value of CHF 10 each, representing 13.97 % of the voting rights in INFICON Holding AG.