Stock Exchange Announcement, September 24, 2007 Change in holding in OMX Citigroup Global Markets Limited (Citigroup) announced today that they have decreased their holding in OMX AB below five (5) percent on September 20, 2007. The holding in OMX AB was decreased with 1,930,583 shares. Thereafter, Citigroup's holding in OMX AB is now 5,628,719 shares which represents 4.67 percent of the shares and votes of OMX AB. The share capital of OMX AB consists of 120 640 467 shares. For further information, please contact: Jakob Håkanson, Vice President, Investor Relations, OMX +46 8 405 60 42