Exhibit 5.1

SKADDEN, ARPS, SLATE, MEAGHER & FLOM LLP
	FOUR TIMES SQUARE NEW YORK 10036-6522 ——	FIRM/AFFILIATE OFFICES ——
	TEL: (212) 735-3000 FAX: (212) 735-2000 www.skadden.com	BOSTON CHICAGO HOUSTON LOS ANGELES PALO ALTO SAN FRANCISCO WASHINGTON, D.C. WILMINGTON ——
	August 7, 2007	BEIJING BRUSSELS FRANKFURT HONG KONG LONDON MOSCOW MUNICH PARIS SINGAPORE SYDNEY TOKYO TORONTO VIENNA

The Nasdaq Stock Market, Inc.

One Liberty Plaza

New York, New York 10006

RE: The Nasdaq Stock Market, Inc. Registration Statement

on Form S-4                                                                             

Ladies and Gentlemen:

We have acted as special counsel to The Nasdaq Stock Market, Inc., a Delaware corporation (the “Company”), in connection with the issuance by the Company of an aggregate of up to 60,516,515 shares of common stock, par value $0.01 per share, of the Company (the “Common Stock”) pursuant to the Transaction Agreement, dated as of May 25, 2007 (the “Transaction Agreement”), between the Company and OMX AB (publ), a public corporation organized under the laws of Sweden.

This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act of 1933, as amended (the “Act”).

In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of (i) the Registration Statement on Form S-4 (the “Registration Statement”) as filed with the Securities and Exchange Commission (the “Commission”) on August 6, 2007 under the Act; (ii) a specimen certificate representing the Common Stock; (iii) the Restated Certificate of Incorporation of the Company, as amended to date and currently in effect; (iv) the By-Laws of the Company, as amended to date and currently in effect; (v) the Transaction Agreement; and (vi) certain resolutions of the Board of Directors of the

The Nasdaq Stock Market, Inc.

August 7, 2007

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Company relating to the approval of the Transaction Agreement and the transactions contemplated thereby, including the issuance of the Common Stock, and related matters. We also have examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates of public officials, certificates of officers or other representatives of the Company and others, and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinion set forth herein.

In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures including endorsements, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as facsimile, electronic, certified or photostatic copies and the authenticity of the originals of such latter documents. In making our examination of executed documents, we have assumed that the parties thereto, other than the Company and its directors and officers, had the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and execution and delivery by such parties of such documents and the validity and binding effect thereof on such parties. As to any facts material to the opinions expressed herein which we have not independently established or verified, we have relied upon statements and representations of officers and other representatives of the Company and others.

Members of our firm are admitted to the bar in the State of New York, and we do not express any opinion as to the laws of any jurisdiction other than the General Corporation Law of the State of Delaware, and we do not express any opinion as to the effect of any other laws on the opinion stated herein.

Based upon and subject to the foregoing, we are of the opinion that when (i) the Registration Statement becomes effective under the Act; (ii) the Offer (as such term is defined in the Transaction Agreement) is declared unconditional and (iii) if issued in physical form, certificates representing shares of Common Stock have been duly executed by the duly authorized officers of the Company in accordance with applicable law or, if issued in book entry form, an appropriate account statement evidencing shares of Common Stock credited to the recipient’s account maintained with the Company’s transfer agent for Common Stock has been issued by said transfer agent, the issuance of the Common Stock will have been duly authorized, and the Common Stock will be validly issued, fully paid and nonassessable.

We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement. We also consent to the reference to our

The Nasdaq Stock Market, Inc.

August 7, 2007

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firm under the caption “Legal Matters” in the Registration Statement. In giving this consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission.

Very truly yours,

/s/ Skadden, Arps, Slate, Meagher & Flom LLP