<Page>
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SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
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SCHEDULE TO/A
TENDER OFFER STATEMENT UNDER SECTION 14(D)(1) OR 13(E)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934
(AMENDMENT NO. 2)
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NEWSEDGE CORPORATION
(Name of Subject Company (Issuer))
--------------------------
INFOBLADE ACQUISITION CORPORATION (OFFEROR)
THE THOMSON CORPORATION (PARENT)
(Names of Filing Persons (identifying status as offeror, issuer or other
person))
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COMMON STOCK, PAR VALUE $0.01 PER SHARE
(TITLE OF CLASS OF SECURITIES)
--------------------------
652 49 Q 10 6
(CUSIP NUMBER OF CLASS OF SECURITIES)
EDWARD A. FRIEDLAND, ESQ.
DEPUTY GENERAL COUNSEL
THE THOMSON CORPORATION
METRO CENTER, ONE STATION PLACE
STAMFORD CONNECTICUT 06902
TELEPHONE (203) 969-8700
(Name, address and telephone number of persons authorized to receive notices and
communications on behalf of filing persons)
--------------------------
COPIES TO:
JOSEPH J. ROMAGNOLI, ESQ.
LEE J. HIRSCH, ESQ.
TORYS
237 PARK AVENUE
NEW YORK, NEW YORK 10017-3142
(212) 880-6000
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/ / 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.
Amount Previously Paid:
Form or Registration No.:
Filing Party:
Date Filed:
/ / 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 13e-4.
/ / going-private transaction subject to Rule 13e-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: / /
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This Amendment No. 2 amends and supplements the Tender Offer Statement on
Schedule TO (the "Schedule TO"), filed on August 21, 2001 with the Securities
and Exchange Commission by InfoBlade Acquisition Corporation, a Delaware
corporation ("Purchaser") and an indirect wholly owned subsidiary of The Thomson
Corporation, a corporation organized under the laws of Ontario, Canada
("Thomson"). The Schedule TO relates to the offer by Purchaser to purchase all
the outstanding shares of common stock, par value $0.01 ("Shares"), of NewsEdge
Corporation, a Delaware corporation ("NewsEdge"), at a purchase price of $2.30
per Share, net to the seller in cash, upon the terms and subject to the
conditions set forth in the Offer to Purchase dated August 21, 2001 (the "Offer
to Purchase") and in the related Letter of Transmittal, copies of which are
filed as Exhibits (a)(1) and (a)(2), respectively to the Schedule TO (which,
together with any amendments or supplements thereto, collectively constitute the
"Offer") and which are hereby incorporated by reference. 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 information:
On September 18, 2001, Thomson issued a press release announcing the
extension of the Offer until 12:00 midnight (EDT), on Tuesday, September 25,
2001. Thomson also announced that it had been advised by Computershare Trust
Company of New York, the Depositary for the Offer, that as of 12:00 p.m. (EDT),
on September 17, 2001, 9,498,647 Shares had been tendered. The press release
which is attached hereto as Exhibit(a)(10) is incorporated by reference herein.
ITEM 12. MATERIALS TO BE FILED AS EXHIBITS.
Item 12 of the Schedule TO is hereby amended and supplemented to include the
following information:
<Table>
(a)(10) Press Release issued by Thomson on September 18, 2001.
</Table>
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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.
<Table>
Dated: September 18, 2001 INFOBLADE ACQUISITION CORPORATION
By: /s/ EDWARD A. FRIEDLAND
-----------------------------------------
Name: Edward A. Friedland
Title: Vice President and Secretary
</Table>
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.
<Table>
Dated: September 18, 2001 THE THOMSON CORPORATION
By: /s/ MICHAEL S. HARRIS
-----------------------------------------
Name: Michael S. Harris
Title: Senior Vice President,
General Counsel and Secretary
</Table>
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EXHIBIT INDEX
<Table>
<Caption>
EXHIBIT NO.
---------------------
(a)(1) Offer to Purchase dated August 21, 2001.*
(a)(2) Form of Letter of Transmittal.*
(a)(3) Form of Notice of Guaranteed Delivery.*
(a)(4) Form of Letter to Brokers, Dealers, Commercial Banks, Trust
Companies and other Nominees, dated August 21, 2001.*
(a)(5) Form of Letter to Clients for Use by Brokers, Dealers,
Commercial Banks, Trust Companies and other Nominees, dated
August 21, 2001.*
(a)(6) Form of Guidelines for Certification of Taxpayer
Identification Number on Substitute Form W-9.*
(a)(7) Summary Advertisement as published in The Wall Street
Journal on August 21, 2001.*
(a)(8) Joint Press Release issued by Thomson and NewsEdge on
August 7, 2001.*
(a)(9) Press Release issued by Thomson on August 21, 2001.*
(a)(10) Press Release issued by Thomson on September 18, 2001.
(b) None.
(d)(1) Agreement and Plan of Merger, dated as of August 6, 2001,
among Thomson, Purchaser and NewsEdge. (The exhibits and
schedules to the Agreement and Plan of Merger are not filed
as part of this Schedule TO. A list briefly identifying the
contents of the omitted exhibits and schedules appears in
the table of contents to the Agreement and Plan of Merger.
Thomson and Purchaser undertake to furnish supplementally a
copy of any omitted exhibit or schedule to the Commission
upon request.)*
(d)(2) Confidentiality Agreement dated May 16, 2001, between
Broadview International LLC, on behalf of NewsEdge, and West
Group, an affiliate of Thomson.*
(d)(3) Stockholders Agreement, dated August 6, 2001, among Thomson,
Purchaser and each of Ronald Benanto, Rory J. Cowan,
James D. Daniell, Murat H. Davidson, Jr., William A.
Devereaux, Michael E. Kolowich, Donald L. McLagan,
Clifford M. Pollan, Basil P. Regan and Peter Woodward
(collectively, the "Selling Stockholders"), together with
Schedule I relating to each Selling Stockholder.*
(d)(4) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Ronald Benanto.*
(d)(5) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and John Crozier.*
(d)(6) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Thomas Karanian.*
(d)(7) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Lee Phillips.*
(d)(8) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Clifford Pollan.*
</Table>
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<Table>
<Caption>
EXHIBIT NO.
---------------------
(d)(9) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and David Scott.*
(d)(10) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Charles White.*
(d)(11) Amended and Restated Executive Employment Agreement, dated
August 6, 2001 between NewsEdge and Alton Zink.*
(g) None.
(h) None.
</Table>
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* Incorporated by reference to Thomson's Schedule TO, filed August 21, 2001.
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