Mittal Steel has announced the commencement of the previously announced US offer for ordinary shares and convertible bonds of Arcelor SA held by US holders and for all Arcelor American Depositary Shares, each ADS representing one ordinary share of Arcelor. The US offer and withdrawal rights are scheduled to expire at 12:00 midnight, New York City Time, on 5 July 2006, unless extended. Goldman, Sachs & Co., Citigroup Global Markets Inc., Credit Suisse Securities (USA) LLC, HSBC Securities (USA) Inc and SG Americas Securities LLC are acting as Dealer Managers for the US offer. DF King & Co. Inc. is the Information Agent. Mittal is offering to exchange: 1 Mittal Steel class A common share and EUR 10.05 in cash for each Arcelor Share or Arcelor ADS tendered;(1) and 1 Mittal Steel class A common share and EUR 12.92 in cash for each Convertible Bond tendered.(2). In addition to, or instead of, the above primary offer, holders of Arcelor shares or ADSs may elect to participate in one or both of two secondary capped offers, one for cash only and the other for Mittal Steel class A common shares only. Pursuant to the secondary offers, Mittal is offering to exchange: EUR 36.69 in cash for each Arcelor Share or Arcelor ADS tendered in the secondary cash offer;(3) or 1.3773 Mittal Steel class A common shares for each Arcelor Share or Arcelor ADS tendered in the secondary exchange offer.(4).