SC TO-T/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Amendment No. 4

Tender Offer Statement under Section 14 (d)(1) or 13 (e)(1)

of the Securities Exchange Act of 1934

Oregon Steel Mills, Inc.

(Name of Subject Company (Issuer))

Oscar Acquisition Merger Sub, Inc.

Evraz Group S.A.

(Names of Filing Persons (Offerors))

Common Stock, par value $0.01 per share

 (including the associated preferred stock purchase rights)

(Title of Class of Securities)

686079104

(CUSIP Number of Class of Securities)

Alexander V. Frolov

Chairman of the Board of Directors

Evraz Group S.A.

1 Allée Scheffer

L-2520 Luxembourg

+7 (495) 232-1370

(Name, Address and Telephone Numbers of Person

Authorized to Receive Notices and Communications on Behalf of Filing Persons)

Copy to:

William A. Groll, Esq.
Neil Q. Whoriskey, Esq.

Cleary Gottlieb Steen & Hamilton LLP

One Liberty Plaza

New York, NY 10006

(212) 225-2000

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$2,300,201,998	$246,122

*For purposes of calculating the filing fee pursuant to Rule 0-11(d) only, the Transaction Valuation was calculated on the basis of (i) the aggregate of 36,366,830 shares of common stock, par value $0.01 per share, of Oregon Steel Mills, Inc. outstanding on a fully diluted basis, consisting of: (a) 35,818,848 shares of common stock issued and outstanding, (b) 156,911 shares of common stock issuable on or before expiration of the offer pursuant to existing stock options, (c) 15,591 shares of common stock subject to lapse or vesting restrictions and (d) 375,480 shares of common stock underlying other outstanding equity awards and (ii) the tender offer price of $63.25 per share of common stock.

**The filing fee, calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, is calculated by multiplying the Transaction Valuation by 0.000107.

xCheck the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid: $246,122	Filing Party: Oscar Acquisition Merger Sub, Inc. and Evraz Group S.A.
Form or Registration No.: Schedule TO-T	Date Filed: November 30, 2006

o	Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.
	Check the appropriate boxes below to designate any transactions to which the statement relates:
x	third-party tender offer subject to Rule 14d-1.
o	issuer tender offer subject to Rule 13e-4.
o	going-private transaction subject to Rule 13e-3.
o	amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer: o

This Amendment No. 4 amends and supplements the Tender Offer Statement on Schedule TO (the “Schedule TO”) filed with the United States Securities and Exchange Commission on November 30, 2006, as amended on December 5, 2006, December 11, 2006, and December 22, 2006 by Evraz Group S.A., a company organized as a société anonyme under the laws of the Grand Duchy of Luxembourg (“Evraz”), and its wholly owned subsidiary Oscar Acquisition Merger Sub, Inc. (“Purchaser”), a Delaware corporation.

The Schedule TO relates to the offer by Purchaser to purchase all outstanding shares of common stock, par value $0.01 per share (including the associated preferred stock purchase rights, “Shares”), of Oregon Steel Mills, Inc., a Delaware corporation, at a price of $63.25 per Share, net to the seller in cash, without interest thereon and less any required withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase dated November 30, 2006 (the “Offer to Purchase”) and in the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the “Offer”), which are annexed to the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively.  Capitalized terms used but not defined herein shall have the meanings assigned to such terms in the Offer to Purchase.

Items 1 through 11.

Items 1, 4 and 11 of the Schedule TO are hereby amended and supplemented as follows:

“On December 28, 2006, Evraz issued a press release announcing that the Offer has been extended until 5:00 pm, New York City time on January 9, 2007, unless further extended or earlier terminated.  The Offer was previously scheduled to expire at 12:00 midnight, New York City time, on December 28, 2006.  Based on information provided by Mellon Investor Services LLC, the depositary for the Offer, as of 5:00 pm New York City time on December 27, 2006, stockholders of Oregon Steel had tendered into the Offer 9,607,810 shares of Oregon Steel common stock.  Except for the extension of the expiration date, all of the other terms and conditions of the tender offer remain unchanged.  A copy of the press release is filed as Exhibit (a)(1)(J).”

Item 12.  Exhibits.

Item 12 of the Schedule TO is hereby amended and supplemented to add the following exhibit:

“(a)(1)(J)  Text of press release issued by Evraz on December 28, 2006.”

2

SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: December 28, 2006

Evraz Group S.A.
By:	/s/ Pavel S. Tatyanin
Name:	Pavel S. Tatyanin
Title:	Authorized Signatory

Oscar Acquisition Merger Sub, Inc.
By:	/s/ Timur I. Yanbukhtin
Name:	Timur I. Yanbukhtin
Title:	Authorized Signatory

3

EX-99.A1J

Exhibit(a)(1)(J)

Evraz Extends Tender Offer to Acquire Oregon Steel Mills

Luxembourg, December 28, 2006–Evraz Group S.A. (LSE: EVR) today announced that the cash tender offer by its wholly owned subsidiary Oscar Acquisition Merger Sub, Inc. to purchase all outstanding shares of common stock (including the associated preferred stock purchase rights) of Oregon Steel Mills, Inc. (NYSE: OS) is being extended until 5:00 p.m., New York City time, on January 9, 2007, unless further extended or earlier terminated.  The tender offer had previously been scheduled to expire at 12:00 midnight on December 28, 2006.

As previously indicated by Evraz, the initial expiration date for the tender offer is being extended to permit the tender offer to remain open until after January 8, 2007, the expiration date of the previously announced 30-day review by the Committee on Foreign Investment in the United States (CFIUS).  Under the Merger Agreement, if all of the conditions to the tender offer are not satisfied as of any expiration date, Evraz will have the right, and under certain circumstances may be required, to further extend the tender offer.

Evraz and Oscar Acquisition Merger Sub, Inc. have been advised by Mellon Investor Services LLC, the depositary for the tender offer, that as of 5:00 pm New York City time on December 27, 2006, stockholders of Oregon Steel had tendered into the tender offer 9,607,810 shares of Oregon Steel common stock. 

The tender offer is being made pursuant to a previously announced definitive merger agreement among Evraz, Oscar Acquisition Merger Sub, Inc. and Oregon Steel dated November 20, 2006. Upon the successful closing of the tender offer, Oregon Steel stockholders would receive $63.25 in cash for each share of Oregon Steel common stock tendered in the tender offer, less any required withholding taxes.  Following the purchase of shares in the tender offer, Oregon Steel would become a subsidiary of Evraz.  Except for the extension of the expiration date, all of the other terms and conditions of the tender offer remain unchanged. 

The description contained herein is neither an offer to purchase nor a solicitation of an offer to sell shares of Oregon Steel.  Evraz and Oscar Acquisition Merger Sub, Inc., have filed with the Securities and Exchange Commission a tender offer statement on Schedule TO, and have mailed an offer to purchase, forms of letter of transmittal and related documents to Oregon Steel stockholders.  Oregon Steel has filed with the Securities and Exchange Commission, and has mailed to Oregon Steel stockholders, a solicitation/recommendation statement on Schedule 14D-9.  These documents contain important information about the tender offer and stockholders of Oregon Steel are urged to read them carefully.  Stockholders of Oregon Steel may obtain a free copy of these documents at http://www.evraz.com/ and http://www.osm.com/ and the website maintained by the Securities and Exchange Commission at http://www.sec.gov/ or by contacting the information agent for the tender offer, MacKenzie Partners, Inc., at proxy@mackenziepartners.com, (212) 929-5500 (call collect) or (800) 322-2885 (toll free). In addition, stockholders may obtain a free copy of these documents from Evraz by

contacting Evraz at ir@evraz.com or +7-495-2321370, attention: Investor Relations, or from Oregon Steel by contacting Oregon Steel at +1 503 240 5223 attention: Investor Relations.

Forward Looking Statement

This press release contains forward-looking statements. These statements are based on Evraz’s and Oregon Steel’s current expectations and beliefs. Actual results could differ materially from the results implied by these statements. Factors that may cause or contribute to such differences include: the risk that the conditions to the offer or the merger set forth in the merger agreement will not be satisfied, changes in both companies’ businesses during the period between now and the closing, developments in obtaining regulatory approvals for the transaction; timely development, competitive products and pricing, as well as fluctuations in demand; cost and availability of raw materials; potential equipment malfunction; and plant construction and repair delays; the ability to retain key management and technical personnel of Oregon Steel; adverse reactions to the proposed transaction by customers, suppliers and strategic partners and other risks described in Oregon Steel’s report on Form 10-K filed with the Securities and Exchange Commission (SEC) for the fiscal year ended December 31, 2005.  Oregon Steel and Evraz are under no obligation to (and expressly disclaim any such obligation to) update or alter their forward-looking statements whether as a result of new information, future events or otherwise.

#  #  #

For further information:

Evraz Group

Corporate Affairs and Investor Relations

Irina Kibina

Tel: +7 495 232 1370

ir@evraz.com

Edelman, for Evraz:

Susan Stillings / Christopher Mittendorf

Tel: +1 212 704 4559 / 8134 

e-mail:

susan.stillings@edelman.com

christopher.mittendorf@edelman.com

Evraz Group S.A. is one of the largest vertically-integrated steel and mining businesses with operations mainly in Russia. In 2005, Evraz Group produced 13.9 million tonnes of crude steel.  Evraz Group’s principal assets include three of the leading steel plants in Russia: Nizhny Tagil (NTMK) in the Urals region and West Siberian (Zapsib) and Novokuznetsk (NKMK) in Siberia, as well as Palini e Bertoli in Italy and Vitkovice Steel in the Czech Republic. Its fast-growing mining businesses comprise Evrazruda, the Kachkanarsky (KGOK) and Vysokogorsky (VGOK) iron ore mining complexes and Neryungriugol coal company and equity interests in the Raspadskaya and Yuzhkuzbassugol coal mines. The mining assets enable Evraz Group to be a vertically-integrated steel producer. Evraz Group also owns and operates the Nakhodka commercial sea port, in the Far East of Russia, which facilitates its access to Asian export markets. Evraz vanadium operations comprise Strategic Minerals Corporation, USA, and a 24.9% equity interest in Highveld Steel and Vanadium Corporation, South Africa.

For further information visit www.evraz.com