SUMMARY OF THE PROXY STATEMENT/ PROSPECTUS

      This summary highlights selected information in this proxy statement/ prospectus and may not contain all of the information that is important to you. You should carefully read this entire proxy statement/prospectus and the other documents to which you are referred for a more complete understanding of the merger. In particular, you should read the documents attached to this proxy statement/ prospectus, including the merger agreement which is attached as Annex A. In addition, we incorporate by reference into this proxy statement/ prospectus important business and financial information about Mittal Steel and ISG, see “WHERE YOU CAN FIND MORE INFORMATION” on page 1. We have included page references in this summary to direct you to more complete descriptions of the topics presented in this summary.

      Unless otherwise indicated, as used in this proxy statement/prospectus:

Information about Mittal Steel (Page 136) and Park Acquisition Corp.

Mittal Steel Company N.V.

      Mittal Steel is one of the world’s largest steel producers¹ with steel-making operations in fourteen countries. Mittal Steel’s operating philosophy embraces both integrated and mini-mill processes for steel-making. Mittal Steel’s steel shipments have increased from 1.5 million tons in 1992 to 27.4 million tons (including LNM Holdings) in 2003. In fiscal year 2003, Mittal Steel (including LNM Holdings) consolidated sales, operating income and net income were $9,567 million, $1,299 million and $1,182 million, respectively. For the nine months ended September 30, 2004, the consolidated sales, operating income and net income of Mittal Steel (including LNM Holdings) were $16,019 million, $4,419 million and $3,147 million, respectively.

Park Acquisition Corp.

      Park Acquisition Corp. is a Delaware corporation and a wholly owned subsidiary of Mittal Steel created solely for the purpose of entering into the transactions contemplated under the merger agreement. Park Acquisition Corp. has not conducted any activities other than those incidental to its formation and the entering into of the merger agreement.

Information about ISG (Page 163)

International Steel Group Inc.

      ISG is one of the largest integrated steel producers in North America² with annual raw steel production capability of about 23 million net tons. ISG ships a variety of steel products from 13 major steel producing and finishing facilities in eight states. ISG has grown by acquiring out of bankruptcy the steel-making assets of LTV Steel Company Inc., or LTV, Acme Steel Company, or Acme, Bethlehem Steel Corporation, or Bethlehem, Weirton Steel Corporation, or Weirton, and Georgetown Steel Corporation, or Georgetown. For the nine months ended September 30, 2004, net sales, income from operations and net income were $6,462.4 million, $556.4 million and $421.4 million, respectively.

The Merger (Page 48)

      In the merger, ISG will merge with Park Acquisition Corp., a wholly owned subsidiary of Mittal Steel, and either Park Acquisition Corp. or ISG will continue as the surviving company and as a wholly owned subsidiary of Mittal Steel.

Merger Consideration (Page 83)

      As consideration for each share of ISG common stock exchanged in the merger, ISG stockholders may elect to receive:

      The number of Mittal Steel class A common shares to be exchanged for each share of ISG common stock will be based on an exchange ratio determined by reference to the average closing price of Mittal Steel class A common shares on the New York Stock Exchange during the 20-trading-day period ending on (and including) the trading day that is two days prior to the effective time of the merger. The maximum and minimum number of Mittal Steel class A common shares to be issued in connection with the merger limit the variation in the exchange ratio so that if the average closing price of Mittal Steel class A common shares is:

      Under the merger agreement, 50% of the issued and outstanding shares of ISG common stock must be exchanged for cash, and the other 50% must be exchanged for Mittal Steel class A common shares.

      As a result, the number of Mittal Steel class A common shares that ISG stockholders receive in the merger will depend on the market prices for Mittal Steel class A common shares during the measurement period prior to the merger. ISG stockholders should therefore review these prices prior to making a decision on the merger or as to which election to make. The portion of the merger consideration payable in cash will not fluctuate from $42.00 per share of ISG common stock.

      The total number of Mittal Steel class A common shares that will be issued as consideration in the merger, will be between approximately 47,949,732 shares and 60,891,883 shares (assuming that 100,035,950 shares of ISG common stock are issued and outstanding at the effective time of the merger and 50% of such shares are converted into Mittal Steel class A common shares).

      The following table illustrates the number of Mittal Steel class A common shares that may be issued in the merger, using a range of illustrative values for the average closing price of Mittal Steel class A common shares during the 20-trading-day period ending on (and including) the trading day that is two days prior to the effective time of the merger. Please refer to “MARKET DATA” beginning on page 247 for historical data on the share price of Mittal Steel class A common shares.

Recommendation of the ISG Board of Directors (Page 52)

      The ISG board of directors:

Opinions of ISG’s Financial Advisors (Page 57)

      UBS Securities LLC, or UBS, and Goldman, Sachs & Co., or Goldman Sachs, ISG’s financial advisors, each rendered its opinion, dated October 24, 2004, to the ISG board of directors that, based upon and subject to the factors, assumptions and procedures set forth therein, it is UBS’ and Goldman Sachs’ opinion that as of October 24, 2004, the consideration to be received by the holders of ISG common stock in the merger, taken in the aggregate, is fair from a financial point of view to such holders.

      The full text of the written opinions of UBS and Goldman Sachs, each dated October 24, 2004, which set forth the assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with each opinion, are attached as Annexes E and F, respectively, to this proxy statement/prospectus. UBS and Goldman Sachs each provided its opinion for the information and assistance of the ISG board of directors in connection with its consideration of the transaction contemplated by the merger agreement. The UBS and Goldman Sachs opinions are not recommendations as to how any holder of shares of ISG common stock should vote or make any election with respect to the transaction contemplated by the merger agreement. ISG stockholders are urged to read these opinions carefully and in their entirety.

Conditions of the Merger (Page 98)

      Before the merger can be completed, a number of conditions must be satisfied, including:

      The parties currently believe that all regulatory merger approvals required prior to completing the merger have been received. These include the merger clearance decision required under German Law which has been issued and notice of the early termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act. In addition, the acquisition of LNM Holdings was completed on December 17, 2004 and the Mittal Steel class A common shares that will be issued as consideration in the merger have been approved for listing by the New York Stock Exchange, subject to official notice of effectiveness of the merger.

      The parties expect to complete the merger on or around April 13, 2005, after the receipt of the required approvals of the ISG stockholders at the ISG special meeting and the Mittal Steel shareholders at the Mittal Steel extraordinary meeting and subject to satisfaction or waiver of all remaining conditions of the merger.

      Neither Mittal Steel nor ISG currently expects to waive any material condition to completion of the merger. If either Mittal Steel or ISG determines to waive any condition to the merger that would result in a material and adverse change in the terms of the merger to ISG stockholders (including any change in the tax consequences of the transaction to ISG stockholders), we would circulate a revised proxy statement/ prospectus and resolicit stockholder approval.

Termination of the Merger Agreement (Page 100)

      ISG and Mittal Steel may agree in writing to terminate the merger agreement at any time prior to the effective time of the merger without completing the merger, even after the ISG stockholders and /or the Mittal Steel shareholders have adopted the merger agreement. The merger agreement may also be terminated at any time prior to the effective time of the merger in certain other circumstances, including:

Fees and Expenses (Page 102)

      Under certain circumstances, in connection with termination of the merger agreement, ISG will be required to pay Mittal Steel a fee of $130 million and, in certain other circumstances, reimburse Mittal Steel for certain expenses incurred in connection with the merger up to $10 million. In certain other circumstances, Mittal Steel is required to reimburse ISG for certain expenses of ISG incurred in connection with the merger up to $10 million.

No Solicitation of Transactions (Page 93)

      The merger agreement contains customary restrictions on the ability of ISG to solicit or engage in discussions or negotiations with a third party regarding specified transactions involving ISG. Notwithstanding these restrictions, the ISG board of directors may respond to an unsolicited written bona fide proposal for a competing transaction or terminate the merger agreement and enter into an acquisition agreement with respect to a superior proposal.

Richmond Support Letter Agreement (Page 106)

      In connection with Mittal Steel entering into the merger agreement, at the request of ISG, The Richmond Investment Holdings Limited (an entity owned by Mr. Lakshmi Mittal, the Chairman of the board of directors and Chief Executive Officer of Mittal Steel, and his wife, Mrs. Usha Mittal, who together are the controlling shareholder of Mittal Steel), at the time the sole shareholder of LNM Holdings, made certain representations and warranties to ISG as of the date of the Richmond support letter agreement with respect to LNM Holdings and the LNM Holdings acquisition agreement and provided ISG with certain rights to conduct due diligence with respect to LNM Holdings between October 24, 2004 and the effective time of the merger.

      In addition, pursuant to the Richmond support letter agreement, The Richmond Investment Holdings Limited agreed that from the date of the Richmond support letter agreement to the earlier of the termination of the merger agreement and the completion of the acquisition of LNM Holdings by Ispat International, The Richmond Investment Holdings Limited will cause LNM Holdings not to declare any dividends or distributions with respect to the shares of LNM Holdings or repurchase any of such shares, except for the payment of dividends permitted or otherwise contemplated by the LNM Holdings acquisition agreement. As described above, the acquisition of LNM Holdings was completed on December 17, 2004. The LNM Holdings acquisition agreement specifically permits LNM Holdings to pay a $2 billion dividend to its then sole shareholder, which dividend was previously declared on October 11, 2004. LNM Holdings has made dividend payments totaling $625 million to The Richmond Investment Holdings Limited as of the date of this proxy statement/prospectus and has indicated that it intends to pay the balance of this dividend to The Richmond Investment Holdings Limited in 2005. This dividend will be entirely paid from cash flow from operations. Mittal Steel does not anticipate using any borrowings to pay this dividend.

Parent Shareholder Support Agreement (Page 108)

      In connection with Mittal Steel entering into the merger agreement, at the request of ISG, Ispat International Investments, S.L. entered into a parent shareholder support agreement with ISG. The parent shareholder support agreement provides, among other things, that Ispat International Investments, S.L. will vote all of its Mittal Steel class A common shares and Mittal Steel class B common shares in favor of approval of the merger agreement. Ispat International Investments, S.L. owns 26,100,000 Mittal Steel class A common shares and 72,150,000 Mittal Steel class B common shares, representing approximately 15.7% of the

Company Shareholder Support Agreement (Page 110)

      In connection with ISG entering into the merger agreement, Wilbur L. Ross, Chairman of the ISG board of directors, and certain affiliates of Mr. Ross and Rodney B. Mott, ISG’s President and Chief Executive Officer and a member of the ISG board of directors, entered into a company shareholder support agreement required by Mittal Steel in connection with its entering into the merger agreement. Among other things, this agreement provides that they will each vote all of the shares of ISG common stock they own in favor of the adoption of the merger agreement. Mr. Ross and certain affiliates of Mr. Ross and Mr. Mott beneficially owned 6.9% and 1.4%, respectively, of the shares of ISG common stock outstanding as of the record date. These percentages do not include shares deemed to be beneficially owned by virtue of owning unexercised options. This covenant terminates automatically if the merger agreement is terminated, regardless of the circumstances. In addition, the ISG stockholder parties granted an irrevocable option to Mittal Steel to purchase each such stockholder’s shares of ISG common stock at $38.50 per share. Mittal Steel paid the grantors of these options $3.50 per option share, which amount will be credited against the merger consideration receivable by the grantors in the merger. The option becomes exercisable under certain circumstances upon the termination of the merger agreement, but expires on April 30, 2005.

Directors and Senior Management Following the Merger (Page 114)

      Following the merger, the directors and senior management of Mittal Steel are expected to include (among others) the following individuals:

      The merger agreement and related documentation do not guarantee that Mr. Ross or Mr. Mott will serve in these roles with Mittal Steel for any specified period after the merger. It is also expected that Mr. Ross and Mr. Mott will join the board of directors of Mittal Steel’s U.S. subsidiary after the merger.

Interest of Certain Persons in the Merger (Page 129)

      In considering the recommendation of the ISG board of directors to vote for the adoption of the merger agreement, ISG stockholders should be aware that certain members of the ISG board of directors and executive officers of ISG may have interests in the merger that differ from, or are in addition to, their interests as ISG stockholders. The ISG board of directors was aware of these interests and considered them, among other matters, in approving the merger agreement and the merger. A summary of these interests, in addition to the interests arising out of the company shareholder support agreement and the expected roles in Mittal Steel’s management described in the preceding two sections, is set forth below.

      ISG’s executive severance pay plan provides officers of ISG certain benefits following a termination of employment, consisting of cash payments and continuation of certain benefits for a period of six to twenty-four months. Messrs. Anthony, Goodwin, Hernandez, Mott and Nelson are not participants in the executive severance pay plan. Mr. Arnett, Ms. Smith and Mr. Spelich, among others, are participants in the plan. If the employment of any of these ISG executives is terminated involuntarily without “cause,” voluntarily for “good reason” or involuntarily for any reason within six months of a change-in-control and the termination is in connection with the merger, these benefits are enhanced to include a bonus payment equal to the average bonus amounts paid with respect to the previous three calendar years (or, if employed for less than three years, the shorter period) and an additional lump sum cash payment equal to six months of salary. This severance amount may not exceed twice the ISG officer’s annual compensation during the year immediately preceding termination of employment with ISG (or, if employed for less than one year, the year of termination).

      The estimated value of the severance benefits payable to Mr. Arnett, Ms. Smith and Mr. Spelich, assuming a qualifying termination occurs in connection with the merger, would be approximately $800,000, $700,000 and $900,000, respectively.

Accounting Treatment and Considerations (Page 68)

      Mittal Steel will account for the merger as a purchase for financial reporting purposes.

Material U.S. Federal Income Tax Consequences of the Merger to ISG Stockholders (Page 68)

      The U.S. federal income tax consequences of the merger to an ISG stockholder will depend on the form of consideration received by such stockholder in the merger. An ISG stockholder that receives solely Mittal Steel class A common shares in exchange for such stockholder’s ISG common stock will not recognize any gain or loss for U.S. federal income tax purposes (except with respect to cash received instead of fractional shares). An ISG stockholder who receives part cash and part Mittal Steel class A common shares, and who has an adjusted tax basis in ISG common stock that is less than the sum of the amount of cash and the fair market value (as of the date of the merger) of the Mittal Steel class A common shares received in the merger, will recognize a gain equal to the amount of such difference or, if less, the amount of cash received in the merger. However, if an ISG stockholder’s adjusted tax basis in ISG common stock is greater than the sum of the amount of cash and the fair market value (as of the date of the merger) of the Mittal Steel class A common shares received for the ISG common stock, the resulting loss will not currently be allowed for U.S. federal income tax purposes. If an ISG stockholder receives solely cash, gain or loss generally will be recognized by such stockholder to the extent of the difference between the amount of cash received and such stockholder’s adjusted tax basis in such stockholder’s ISG common stock.

      The consequences described above assume that the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code and that Section 367(a)(1) of the Internal Revenue Code does not apply to the receipt of Mittal Steel class A common shares by the ISG stockholders. The same U.S. federal income tax consequences generally will apply to ISG stockholders in the event Mittal Steel effects the merger pursuant to a reverse-subsidiary merger which, together with the recently completed acquisition of the shares of LNM Holdings, qualifies as transfers of property described in Section 351(a) of the Internal Revenue Code. Completion of the merger is conditioned on receipt of certain tax opinions as described below under “THE MERGER — Material U.S. Federal Income Tax Consequences of the Merger and the Ownership of Mittal Steel Class A Common Shares Received by ISG Stockholders” beginning on page 68.

      THE TAX CONSEQUENCES OF THE MERGER TO AN ISG STOCKHOLDER WILL DEPEND ON EACH STOCKHOLDER’S INDIVIDUAL SITUATION. ISG STOCKHOLDERS

Material Dutch Tax Consequences of the Merger to Dutch Resident ISG Stockholders (Page 75)

      Under Dutch tax laws the exchange of shares of ISG common stock for cash and/or Mittal Steel class A common shares will not qualify as a tax free merger. Consequently, any capital gain that may be realized upon the exchange of shares of ISG common stock for cash and/or Mittal Steel class A common shares by individuals and corporate entities who are resident or deemed to be resident in The Netherlands for Dutch tax purposes, or Dutch resident individuals and Dutch resident entities may be subject to Dutch income or corporate income tax. For Dutch resident individuals any such capital gain will generally not be subject to tax, provided that the Mittal Steel class A common shares are not attributable to an enterprise from which such individual derives a share of the profit, whether as an entrepreneur or as a person who has a co-entitlement to the net worth of such enterprise without being a shareholder and such individual does not have an actual or deemed substantial interest (statutorily defined term; see page 78 for a further description) in Mittal Steel. For Dutch resident entities a capital gain will generally not be subject to tax if such entity is a qualifying Dutch pension fund or Dutch resident investment fund (fiscale beleggingsinstelling) or if the Dutch participation exemption applies to the Mittal Steel class A common shares. Please see the section “THE MERGER — Material Dutch Tax Consequences of the Merger and the Ownership of Mittal Steel Class A Common Shares to ISG Stockholders” beginning on page 75 for a more detailed description of the taxation of Dutch resident individual and corporate shareholders.

      THE TAX CONSEQUENCES OF THE MERGER TO A DUTCH RESIDENT ISG STOCKHOLDER WILL DEPEND ON THE STOCKHOLDER’S OWN SITUATION. ISG STOCKHOLDERS SHOULD CONSULT THEIR OWN ADVISORS FOR A FULL UNDERSTANDING OF THE TAX CONSEQUENCES OF THE MERGER.

Dissenter’s Rights of Appraisal (Page 81 and Annex G)

      The DGCL provides ISG stockholders with appraisal rights in connection with the merger. This means that ISG stockholders are entitled to have the value of their common stock determined by the Delaware Chancery Court and to receive payment based on that valuation. The ultimate amount an ISG stockholder receives as a dissenting stockholder in an appraisal proceeding may be more or less than or the same as they would have otherwise received as consideration under the merger agreement.

      To exercise appraisal rights, an ISG stockholder must deliver a written objection to the merger to ISG at or before the vote on the adoption of the merger agreement at the special meeting and such ISG stockholder must not vote in favor of the adoption of the merger agreement. Failure to follow exactly the procedures specified under the DGCL will result in the loss of such appraisal rights.

      A copy of Section 262 of the DGCL governing the exercise of appraisal rights is attached to this proxy statement/prospectus as Annex G.

Listing of Mittal Steel’s Class A Common Shares (Page 81)

      Mittal Steel’s class A common shares are listed on the New York Stock Exchange, Mittal Steel’s principal U.S. trading market, and outside the United States on Euronext Amsterdam, in each case under the symbol “MT”. In accordance with the terms of the merger agreement, Mittal Steel has made an application to list on Euronext Amsterdam the Mittal Steel class A common shares that Mittal Steel will issue as consideration in the merger, subject to notice of issuance. The Mittal Steel class A common shares that will be issued as consideration in the merger have been approved for listing by the New York Stock Exchange, subject to official notice of effectiveness of the merger. Listing and trading of the Mittal Steel class A common shares that will be issued as consideration in the merger will commence on the New York Stock Exchange on

Comparison of Rights of Shareholders under Delaware Law and Dutch Law (Page 233)

      ISG is organized under the laws of the State of Delaware while Mittal Steel is organized under the laws of The Netherlands. Therefore, your rights as a shareholder of Mittal Steel will be governed by Dutch law and by Mittal Steel’s Articles of Association. These rights differ in certain respects from the current rights of ISG stockholders, which are governed by Delaware law and by ISG’s Certificate of Incorporation and Bylaws. In addition, Mittal Steel class A common shares entitle the holder to one vote per share, while Mittal Steel class B common shares entitle the holder to ten votes per share, on all matters submitted to a vote of Mittal Steel shareholders. Immediately following the completion of the merger, the former ISG stockholders, on a fully diluted basis, will own approximately 7% to 9% of the common shares of Mittal Steel, representing approximately 1% to 1.3% of the combined voting power of Mittal Steel.

ISPAT INTERNATIONAL SELECTED HISTORICAL FINANCIAL DATA

      The following table presents selected consolidated financial information of Ispat International for the years ended December 31, 1999, 2000, 2001, 2002 and 2003 and for the nine months ended September 30, 2003 and 2004 derived from Ispat International’s consolidated financial statements and related notes. This selected historical financial information should be read in conjunction with the respective audited and unaudited consolidated financial statements of Ispat International, including the notes thereto, beginning on page F-20.

      A reconciliation of Sales and Net Sales is given below: