OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
            (INCLUDING THE ASSOCIATED COMMON STOCK PURCHASE RIGHTS)
                                       OF
                              PRIMARK CORPORATION
                                       AT
                              $38.00 NET PER SHARE
                                       BY
                        MARQUEE ACQUISITION CORPORATION
                     AN INDIRECT WHOLLY OWNED SUBSIDIARY OF
                            THE THOMSON CORPORATION
     ----------------------------------------------------------------------
         THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,
 NEW YORK CITY TIME, ON WEDNESDAY, JULY 12, 2000, UNLESS THE OFFER IS EXTENDED.
- --------------------------------------------------------------------------------

                                                                   June 14, 2000

To Brokers, Dealers, Commercial Banks,
  Trust Companies and Other Nominees:

    We have been appointed by Marquee Acquisition Corporation, a Michigan
corporation ("Purchaser") and an indirect wholly owned subsidiary of The Thomson
Corporation, a corporation organized under the laws of Ontario, Canada
("Thomson"), to act as Dealer Manager in connection with Purchaser's offer to
purchase all outstanding shares of Common Stock, no par value per share (the
"Shares"), of Primark Corporation, a Michigan corporation (the "Company"), at a
price of $38.00 per Share, net to the seller in cash, upon the terms and subject
to the conditions set forth in Purchaser's Offer to Purchase, dated June 14,
2000 (the "Offer to Purchase"), and the related Letter of Transmittal (which,
together with the Offer to Purchase and any amendments or supplements thereto,
collectively constitute the "Offer").

    Please furnish copies of the enclosed materials to those of your clients for
whose accounts you hold Shares registered in your name or in the name of your
nominee.

    THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, THERE BEING VALIDLY
TENDERED AND NOT WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER AT LEAST 51% OF
THE SHARES OUTSTANDING ON A FULLY DILUTED BASIS AND THE EXPIRATION OR
TERMINATION OF ANY APPLICABLE ANTITRUST WAITING PERIODS.

    Enclosed for your information and for forwarding to your clients for whom
you hold Shares registered in your name or in the name of your nominee, are
copies of the following documents:

         1. Offer to Purchase, dated June 14, 2000;

         2. Letter of Transmittal for your use in accepting the Offer and
    tendering Shares and for the information of your clients;

         3. Notice of Guaranteed Delivery to be used to accept the Offer if the
    Shares and all other required documents are not immediately available or
    cannot be delivered to ChaseMellon Shareholder Services L.L.C. (the
    "Depositary") by the Expiration Date (as defined in the Offer to Purchase)
    or if the procedure for book-entry transfer cannot be completed by the
    Expiration Date;

         4. A letter to shareholders of the Company from Joseph E. Kasputys,
    Chairman, President and Chief Executive Officer of the Company, together
    with a Solicitation/Recommendation Statement on Schedule 14D-9 filed with
    the Securities and Exchange Commission by the Company;

         5. A letter which may be sent to your clients for whose accounts you
    hold Shares registered in your name or in the name of your nominee, with
    space provided for obtaining such clients' instructions with regard to the
    Offer;

         6. Guidelines for Certification of Taxpayer Identification Number on
    Substitute Form W-9; and

         7. Return envelope addressed to the Depositary.

    WE URGE YOU TO CONTACT YOUR CLIENTS AS PROMPTLY AS POSSIBLE. PLEASE NOTE
THAT THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
TIME, ON WEDNESDAY, JULY 12, 2000, UNLESS THE OFFER IS EXTENDED.

    In all cases, payment for Shares accepted for payment pursuant to the Offer
will be made only after timely receipt by the Depositary of (i) certificates
evidencing such Shares (or a confirmation of a book-entry transfer of such
Shares into the Depositary's account at one of the Book-Entry Transfer
Facilities (as defined in the Offer to Purchase)), (ii) a Letter of Transmittal
(or manually signed facsimile thereof) properly completed and duly executed with
any required signature guarantees or, in the case of a book-entry transfer, an
Agent's Message (as defined in the Offer to Purchase) and (iii) any other
required documents.

    If holders of Shares wish to tender, but cannot deliver such holder's
certificates or cannot comply with the procedure for book-entry transfer prior
to the expiration of the Offer, a tender of Shares may be effected by following
the guaranteed delivery procedure described in "Section 3. Procedures for
Accepting the Offer and Tendering Shares" of the Offer to Purchase.

    Purchaser will not pay any fees or commissions to any broker, dealer or
other person (other than the Dealer Manager, the Depositary and Innisfree M&A
Incorporated (the "Information Agent") as described in the Offer to Purchase) in
connection with the solicitation of tenders of Shares pursuant to the Offer.
However, Purchaser will reimburse you for customary mailing and handling
expenses incurred by you in forwarding any of the enclosed materials to your
clients. Purchaser will pay or cause to be paid any stock transfer taxes payable
with respect to the transfer of Shares to it, except as otherwise provided in
Instruction 6 of the Letter of Transmittal.

    Any inquiries you may have with respect to the Offer should be addressed to
the Information Agent or the undersigned at their respective addresses and
telephone numbers set forth on the back cover page of the Offer to Purchase.

    Additional copies of the enclosed material may be obtained from the
Information Agent, at the address and telephone number set forth on the back
cover page of the Offer to Purchase.

                                          Very truly yours,
                                          MORGAN STANLEY & CO. INCORPORATED

NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU OR
ANY OTHER PERSON THE AGENT OF THOMSON, PURCHASER, THE COMPANY, THE DEALER
MANAGER, THE INFORMATION AGENT OR THE DEPOSITARY, OR OF ANY AFFILIATE OF ANY OF
THEM, OR AUTHORIZE YOU OR ANY OTHER PERSON TO USE ANY DOCUMENT OR TO MAKE ANY
STATEMENT ON BEHALF OF ANY OF THEM IN CONNECTION WITH THE OFFER OTHER THAN THE
ENCLOSED DOCUMENTS AND THE STATEMENTS CONTAINED THEREIN.