<SUBMISSION>
<ACCESSION-NUMBER>0000947871-01-000051
<TYPE>SC TO-T/A
<PUBLIC-DOCUMENT-COUNT>2
<FILING-DATE>20010207
<GROUP-MEMBERS>ARTIST ACQUISITION, INC.
<GROUP-MEMBERS>VNU N V
<GROUP-MEMBERS>VNU N.V.
<SUBJECT-COMPANY>
<COMPANY-DATA>
<CONFORMED-NAME>ACNIELSEN CORP
<CIK>0001019878
<ASSIGNED-SIC>8700
<IRS-NUMBER>061454128
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>SC TO-T/A
<ACT>34
<FILE-NUMBER>005-47591
<FILM-NUMBER>1526648
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>177 BROAD STREET
<CITY>STAMFORD
<STATE>CT
<ZIP>06901
<PHONE>2038344200
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>177 BROAD ST
<CITY>STAMFORD
<STATE>CT
<ZIP>06901
</MAIL-ADDRESS>
</SUBJECT-COMPANY>
<FILED-BY>
<COMPANY-DATA>
<CONFORMED-NAME>VNU N V
<CIK>0001093410
<ASSIGNED-SIC>0000
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>SC TO-T/A
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O VNU USA INC
<STREET2>1515 BROADWAY
<CITY>NEW YORK
<STATE>NY
<ZIP>10036
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O VNU USA INC
<STREET2>1515 BROADWAY
<CITY>NEW YORK
<STATE>NY
<ZIP>10036
</MAIL-ADDRESS>
</FILED-BY>
<DOCUMENT>
<TYPE>SC TO-T/A
<SEQUENCE>1
<FILENAME>0001.txt
<DESCRIPTION>AMENDMENT NO. 4 TO SCHEDULE TO
<TEXT>


    As filed with the Securities and Exchange Commission on February 7, 2001.
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                            ------------------------
                                   SCHEDULE TO
            Tender Offer Statement Under Section 14(d)(1) or 13(e)(1)
                     of the Securities Exchange Act of 1934

                                (Amendment No. 4)
                            ------------------------
                              ACNIELSEN CORPORATION
                            (Name of Subject Company)
                            ------------------------
                            ARTIST ACQUISITION, INC.
                                    VNU N.V.
            (Names of Filing Persons (identifying status as offeror,
                            issuer or other person))
                            ------------------------

                     Common Stock, Par Value $.01 Per Share
           (Including the Associated Preferred Share Purchase Rights)
                         (Title of Class of Securities)
                            ------------------------
                                    004833109
                      (CUSIP Number of Class of Securities)

Th.C.M. van Kampen, Esq.                                   James Ross, Esq.
        VNU N.V.                                              VNU, Inc.
       P.O. Box 1                                            770 Broadway
     200 MA Haarlem                                    New York, New York 10003
     The Netherlands                                        (646) 654-5000
  (011) 31-23-546-3463
      (Name, Address and Telephone Number of Persons Authorized to Receive
            Notices and Communications on Behalf of filing persons)
                            ------------------------
                                   Copies to:

                                John Madden, Esq.
                               Clare O'Brien, Esq.
                               Shearman & Sterling
                              599 Lexington Avenue
                            New York, New York 10022
                                 (212) 848-4000


                            CALCULATION OF FILING FEE

================================================================================
    Transaction Valuation*                     Amount of Filing Fee**
--------------------------------------------------------------------------------
       $2,334,104,773.35                             $466,820.95
================================================================================

*    Estimated for purposes of calculating the amount of the filing fee only.
     The fee was calculated by multiplying $36.75, the per share tender offer
     price, by the 57,830,966 currently outstanding shares of Common Stock
     sought in the Offer, which gives an aggregate consideration of
     $2,125,288,000.50 (the "Common Stock Consideration"). The Common Stock
     Consideration was then added to the product of $16.11, the per share
     consideration for the options (after deduction of the option exercise price
     of $20.64), and 12,961,935, the number of options that will be vested as of
     December 22, 2000, to arrive at a total transaction value of
     $2,334,104,773.75.
**   Calculated as 1/50 of 1% of the transaction value.
[X]  Check 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.
<TABLE>
<CAPTION>
<S>                         <C>                                     <C>              <C>
Amount Previously Paid:    $466,820.95                              Filing Party:    VNU N.V., Artist Acquisition, Inc.
                           ----------------------------------------               --------------------------------------------------
Form or Registration No.:   Schedule TO                               Date Filed:    December 22, 2000
                           ----------------------------------------               --------------------------------------------------
</TABLE>
Check the box if the filing relates solely to preliminary communications made
before the commencement of a tender offer.

Check the appropriate boxes to designate any transactions to which the statement
relates:

[X]  third-party tender offer subject to Rule 14d-1.

[ ]  issuer tender offer subject to Rule 13c-4.

[ ]  going-private transaction subject to Rule13e-3.

[ ]  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.   [ ]
================================================================================

<PAGE>


         This Amendment No. 4 (the "Amendment") amends and supplements the
Tender Offer Statement on Schedule TO filed with the Securities and Exchange
Commission on December 22, 2000 (the "Schedule TO") and as amended by Artist
Acquisition, Inc., a Delaware corporation ("Purchaser") and a wholly owned
subsidiary of VNU N.V., a corporation organized under the laws of the
Netherlands ("Parent"). The Schedule TO relates to the offer by Purchaser to
purchase all outstanding shares of common stock, par value $.01 per share (the
"Shares"), of ACNielsen Corporation, a Delaware corporation (the "Company"), at
a purchase price of $36.75 per Share, net to the seller in cash, upon the terms
and subject to the conditions set forth in the Offer to Purchase dated December
22, 2000 (the "Offer to Purchase") and in the related Letter of Transmittal,
copies of which are filed as Exhibits (a)(1)(i) and (ii) to the Schedule TO
(which, together with the Offer to Purchase and any amendments or supplements
thereto, collectively constitute the "Offer"). Capitalized terms used and not
defined herein shall have the meanings ascribed to such terms in the Offer to
Purchase or in the Schedule TO.

Item 4.  Terms of the Transaction

         Item 4 of the Schedule TO is hereby amended and supplemented by the
following:

         On February 7, 2001, Parent issued a press release announcing the
extension of the Offer until 12:00 midnight, New York City time, Wednesday,
February 14, 2001. Parent also announced that it had been advised by Citibank,
N.A., the depositary for the Offer, that as of the close of business on February
6, 2001, a total of 55,527,922 shares of common stock of the Company, or
approximately 93% of the 59,577,043 shares issued and outstanding had been
tendered. The foregoing description of the press release, which is attached
hereto as Exhibit (a)(5)(iv), is incorporated by reference herein.

Item 11. Additional Information

         Item 11 of the Schedule TO is hereby amended and supplemented by the
following:

         On February 6, 2001, Parent received a letter from the Company,
asserting its right under the Merger Agreement to request that Purchaser extend
the expiration date of the Offer because, at the scheduled expiration date of
the Offer, the condition to the Offer relating to the issuance of a decision
under Article 6(1)(b) or 8(2) of the EC Merger Regulation had not been
satisfied.



                  [Remainder of page intentionally left blank]

<PAGE>


         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:  February 7, 2001

                                            ARTIST ACQUISITION, INC.



                                            By  /s/  James Ross
                                              ----------------------------------
                                              Name:  James Ross
                                              Title: General Counsel

         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:  February 7, 2001

                                            VNU N.V.



                                            By  /s/  T.G.G. Bouwman
                                              ----------------------------------
                                              Name:  T.G.G. Bouwman
                                              Title: Chief Financial Officer


<PAGE>

                                  EXHIBIT INDEX

Exhibit  No.
----------------

(a)(1)(i)        Offer to Purchase dated December 22, 2000.*

(a)(1)(ii)       Form of Letter of Transmittal.*

(a)(1)(iii)      Form of Notice of Guaranteed Delivery.*

(a)(1)(iv)       Form of Letter to Brokers, Dealers, Commercial Banks, Trust
                 Companies and Other Nominees.*

(a)(1)(v)        Form of Letter from Brokers, Dealers, Commercial Banks, Trust
                 Companies and Nominees to Clients.*

(a)(1)(vi)       Form of Guidelines for Certification of Taxpayer Identification
                 Number on Substitute Form W-9.*

(a)(1)(vii)      Summary Advertisement as published in The Wall Street Journal
                 on December 22, 2000.*

(a)(5)(i)        Press Release issued by Parent on December 18, 2000
                 (incorporated by reference to exhibit 99.1 of the Schedule TO-C
                 filed by Parent on December 18, 2000).

(a)(5)(ii)       Presentation by Parent to analysts and investors on December
                 18, 2000, (incorporated by reference to exhibit 99.2 of the
                 Schedule TO-C filed by Parent on December 18, 2000).

(a)(5)(iii)      Press Release issued by Parent on January 24, 2001.+

(a)(5)(iv)       Press Release issued by Parent on February 7, 2001.

(b)              Revolving Credit Facility Agreement, dated December 17, 2000,
                 between Merrill Lynch International and Parent.*

(d)(i)           Agreement and Plan of Merger, dated as of December 17, 2000,
                 among Parent, Purchaser and the Company.*

(d)(ii)          Letter Agreement, dated December 17, 2000, between ACNielsen
                 Corporation and Earl Doppelt.*

(d)(iii)         Letter Agreement, dated December 17, 2000, between ACNielsen
                 Corporation and Michael Connors.*

(d)(iv)          Letter Agreement, dated December 17, 2000, between ACNielsen
                 Corporation and Robert Chrenc.*

(d)(v)           Letter Agreement, dated December 17, 2000, between ACNielsen
                 Corporation and Nicholas Trivisonno.*

--------
* Incorporated by reference to Parent's Schedule TO, filed December 22, 2000.
+ Incorporated by reference to Parent's Schedule TO/A, filed January 24, 2001.
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.(A)(5)(IV)
<SEQUENCE>2
<FILENAME>0002.txt
<DESCRIPTION>PRESS RELEASE
<TEXT>


Press release

Date           February 7, 2001


               VNU ANNOUNCES EXTENSION OF TENDER OFFER FOR ACNIELSEN

               Haarlem, The Netherlands - VNU, a leading media and information
               company, today announced that its wholly owned subsidiary, Artist
               Acquisition, Inc., is extending its offer to purchase all
               outstanding shares of common stock of ACNielsen Corporation
               (NYSE: ART) for USD 36.75 per share, net to seller in cash, until
               12:00 midnight, New York City time, on Wednesday, February 14,
               2001. The offer had previously been scheduled to expire on
               February 6, 2001. The terms of the extended offer otherwise are
               identical to the offer as set forth in offering materials filed
               with the Securities and Exchange Commission on December 22, 2000,
               as amended.

               VNU notified the European Commission of the transaction pursuant
               to the European Union Merger Control Regulation. In the absence
               of a finding by the European Commission that the transaction
               raises serious doubts as to its compatibility with the European
               Common Market, the European Commission will issue, or will be
               deemed to have issued, a decision declaring the transaction to be
               compatible with the European Common Market by February 12, 2001.
               [This is the sole remaining regulatory condition to the offer and
               VNU expects to complete the offer on February 14, 2001 if that
               regulatory condition is satisfied at that time.]

               According to Citibank N.A., the depositary for the offer, as of
               the close of business on February 6, 2001, a total of 55,527,922
               shares of common stock of ACNielsen, or approximately 93% of the
               59,689,051 shares issued and outstanding, had been validly
               tendered and not withdrawn pursuant to the offer (including
               shares tendered via guarantee of delivery).

               Contact:          Rob de Meel, telephone +31 23 546 36 48
               website:          news.vnu.com

               VNU is one of the world's leading media and information companies
               and has leading market positions in marketing & media
               information, business information, directories, consumer
               information, as well as educational information. Worldwide, VNU
               employs approximately 16,000 people and has annual revenues of
               more than EUR 2.8 billion (1999).

               ACNielsen, with 21,000 employees and annual revenues of more than
               USD 1.5 billion, is the world's leading market research firm,
               offering measurement and analysis of marketplace dynamics,
               consumer attitudes and behavior, and new and traditional media in
               more than 100 countries. ACNielsen's clients include leading
               consumer product manufacturers and retailers, service firms,
               media and entertainment companies and the Internet community.

               The offer for all the outstanding shares of ACNielsen common
               stock is being made through, and the foregoing announcement is
               qualified in its entirety by reference to, Artist Acquisition,
               Inc.'s Tender Offer Statement on Schedule TO, including the Offer
               to Purchase dated December 22, 2000, and the related letter of
               transmittal, which can be obtained for free, along with other
               filed documents, at the SEC's website www.sec.gov. ACNielsen
               stockholders should read the Offer to Purchase and related




               VNU by/Communications
               P.O. Box 1, 2000 MA Haarlem, The Netherlands/Telephone
               +31 23 546 36 000/Fax +31 23 546 39 12
               news.vnu.com

<PAGE>

Press release


Date           February 7, 2001
Page           2 of 2

               letter of transmittal in their entirety before making any
               decision as to whether to tender their shares into the offer.

</TEXT>
</DOCUMENT>
</SUBMISSION>
