Mittal Steel Co. has announced on 19 May 2006 its decision to improve its offer made to the security holders of Arcelor SA. The highlights include: -Mix and match offer: 1 Mittal Steel share and EUR 11.10 in cash for 1 Arcelor share; or 17 Mittal Steel shares for every 12 Arcelor shares; or EUR 37.74 in cash for each Arcelor share, subject to adjustments, including with respect to Arcelor’s announced dividend; -Offer values Arcelor at EUR 37.74 per share based on Mittal Steel’s 18 May share price, a premium of: 34% over the previous offer upon launch and 70% over the 26 January 2006 (pre-announcement) Arcelor closing price. Offer values Arcelor at EUR 41.5 per share based on Mittal Steel’s one month average share price. Increase of EUR 9.53 per Arcelor share, implying total equity value for Arcelor of EUR 25.8 billion. Total cash consideration of EUR 7.6 billion, an increase of 57%. Upon completion of the offer, adoption of one-share one-vote structure. A prospectus supplement will be made available in the coming days. Based on the Mittal Steel share closing price, on the NYSE, on 18th May 2006, the revised offer values each Arcelor share at EUR 37.74, which represents a 33.8% premium over the consideration offered in the offer announced by Mittal Steel on 27 January 2006 (ie, EUR 28.21 per Arcelor share), a 17.9% premium over the closing price on Euronext Paris of Arcelor shares on 18 May 2006, and a 69.8% premium over the closing price on Euronext Paris of Arcelor shares on 26 January 2006.