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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
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                                 SCHEDULE 14D-9
 
                               (AMENDMENT NO. 1)
 
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                     SOLICITATION/RECOMMENDATION STATEMENT
                      PURSUANT TO SECTION 14(D)(4) OF THE
                        SECURITIES EXCHANGE ACT OF 1934
 
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                         PLENUM PUBLISHING CORPORATION
 
                           (Name of Subject Company)
 
                         PLENUM PUBLISHING CORPORATION
 
                      (Name of Person(s) Filing Statement)
 
                     COMMON STOCK, PAR VALUE $.10 PER SHARE
 
                         (Title of Class of Securities)
 
                                   729093104
 
                     (CUSIP Number of Class of Securities)
 
                         ------------------------------
 
                                 MARTIN E. TASH
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                         PLENUM PUBLISHING CORPORATION
                               233 SPRING STREET
                            NEW YORK, NEW YORK 10013
                                 (212) 620-8000
 
                 (Name, Address and Telephone Number of Person
                Authorized to Receive Notice and Communications
                  on Behalf of the Person(s) Filing Statement)
 
                         ------------------------------
 
                                WITH A COPY TO:
 
                             BERNARD BRESSLER, ESQ.
                          BRESSLER, AMERY & ROSS, P.C.
                                17 STATE STREET
                            NEW YORK, NEW YORK 10004
                                 (212) 425-9300
 
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    This Amendment No. 1 amends the Solicitation/Recommendation Statement on
Schedule 14D-9 filed with the Securities and Exchange Commission on June 16,
1998 by Plenum Publishing Corporation (the "Company"), a Delaware corporation,
relating to the tender offer by PPC Acquisition Corp. ("Purchaser"), a Delaware
corporation and wholly-owned subsidiary of Kluwer Boston, Inc. ("Parent"), a
Massachusetts corporation, for all of the outstanding shares of common stock,
par value $.10 per share, of the Company.
 
ITEM 4. THE SOLICITATION OR RECOMMENDATION.
 
    Item 4(b) is hereby amended as follows:
 
    The eighth and ninth paragraphs are deleted in their entirety and replaced
with the following:
 
        From May 29 through June 3, 1998, Salomon Smith Barney, the Company and
    the Company's legal counsel met to evaluate the responses received from the
    potential purchasers. After such discussions, the Company concluded that the
    proposal submitted by Wolters Kluwer U.S. on behalf of Parent (the "Wolters
    Kluwer Proposal") appeared to be the most favorable to the Company and its
    stockholders, both as to price and other terms, and authorized Salomon Smith
    Barney to begin negotiations with Parent and its financial advisors on
    several issues. The Wolters Kluwer Proposal provided for a tender offer
    price of $72.00 per share and a Termination Fee (as defined in the Merger
    Agreement) of $12,500,000 (in contrast to the $5,000,000 Termination Fee
    offered by the Company) which would be payable by the Company under the
    circumstances provided in the Merger Agreement, including the occurrence of
    certain events on or before June 30, 1999 (in contrast to December 31, 1998
    offered by the Company). The Wolters Kluwer Proposal also included a
    requirement that the Company execute a Stock Option Agreement granting
    Parent the option to purchase 19.9% of the outstanding shares of common
    stock of the Company.
 
        On June 3, 1998, Salomon Smith Barney discussed the Wolters Kluwer
    Proposal with Parent's financial advisor. After these discussions, Parent
    agreed to increase the tender offer price to $73.50 per share and to a
    Termination Fee of $7,500,000, which fee would be triggered by, among other
    circumstances set forth in the Merger Agreement, the occurrence of certain
    events on or before March 31, 1999. On the evening of June 3, 1998, the
    Company and the Company's legal counsel discussed the merits of the amended
    Wolters Kluwer Proposal. At the conclusion of this discussion, the Company
    determined to enter into exclusive negotiations with Parent through their
    respective financial and legal advisors. On June 4, 1998, the Company's
    legal counsel and legal counsel for Parent negotiated provisions of the
    Merger Agreement and Stock Option Agreement and agreement was reached on all
    substantive matters subject to final approval and completion of legal
    documentation. On that date the parties executed an Exclusivity Agreement
    pursuant to which Parent agreed to keep its offer open until June 24, 1998,
    and in exchange the Company agreed to deal only with Parent.
 
    The fourteenth paragraph is deleted in its entirety and replaced with the
following:
 
        In approving the Offer, the Merger, the Merger Agreement and the other
    transactions contemplated thereby and recommending that all holders of
    Shares accept the Offer and tender their Shares pursuant to the Offer, the
    Company Board considered a number of factors. The material factors
    considered by the Board were:
 
           1. The presentations and views expressed by management of the Company
       (at the meeting of the Company Board held on June 10, 1998, and at
       previous meetings of the Company Board) regarding, among other things:
       (a) the financial condition, results of operations, cash flows, business
       and prospects of the Company, which led to the belief that the prospects
       for internal growth of the Company and increased stockholder value if the
       Company remained independent were limited because of the unavailability
       of sources of such growth which the Company could afford without undue
       risk; (b) the absence of affordable strategic alternatives such as
       acquisitions
 
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       and new products; (c) the fact that in view of the discussions held with
       various parties, as well as the Auction Process conducted, it appeared to
       be unlikely that any other party would propose an acquisition or
       strategic business combination that would be more favorable to the
       Company and its stockholders than the Offer and the Merger; and (d) the
       recommendation of the Merger by the management of the Company and the
       willingness of certain officers of the Company to enter into binding
       commitments to sell the stock owned by them.
 
           2. The opinion of Salomon Smith Barney, expressed orally at the June
       10, 1998 Board meeting (and subsequently confirmed in writing), to the
       effect that, as of June 10, 1998, the consideration to be received by the
       Company's stockholders pursuant to the Merger Agreement is fair, from a
       financial point of view, to the Company's stockholders. The full text of
       the opinion of Salomon Smith Barney, dated June 10, 1998, which sets
       forth the assumptions made, matters considered and limitations on the
       review undertaken by Salomon Smith Barney, is attached hereto as EXHIBIT
       12. Stockholders are urged to read the opinion of Salomon Smith Barney
       carefully in its entirety for information concerning the assumptions
       made, matters considered and the limits of the review undertaken by
       Salomon Smith Barney.
 
           3. The historical market prices, the recent limited trading activity
       of the Shares and the fact that the Offer Price represents a premium of
       approximately 58% over the reported closing price of the Shares on the
       National Association of Securities Dealers Automatic Quotation system on
       the last full trading day preceding the public announcement of the
       retention of Salomon Smith Barney.
 
           4. The results of the inquiries made by the Company's management and
       financial advisor in the Auction Process regarding a possible sale of the
       Company and the public nature of the Auction Process itself, which
       demonstrated that the transaction involving the Offer and the Merger
       would be the most favorable which the Company and its stockholders could
       obtain.
 
           5. The arms-length negotiations between the Company and the Parent
       leading to the belief of the Company Board that $73.50 per Share
       represents the highest price per Share that could be negotiated with
       Parent.
 
           6. The fact that the Offer and the Merger provide for a prompt
       all-cash tender offer for all Shares to be followed by a merger for the
       same consideration, thereby enabling the Company's stockholders to obtain
       the benefits of the transaction in exchange for their Shares at the
       earliest possible time.
 
           7. Other provisions of the Offer and the Merger Agreement, including
       the parties' representations, warranties and covenants, the conditions to
       their respective obligations, and the limited ability of Parent and the
       Purchaser to terminate the Wolters Kluwer Proposal or the Merger
       Agreement.
 
           8. The ability of the Company to withdraw from the Merger Agreement
       if an appropriate Superior Proposal is received.
 
           9. The business reputation and capabilities of Parent and its
       management and Parent's financial strength, including its warranted
       ability to fund the offer.
 
    A new paragraph is added as the second to last paragraph which provides as
follows:
 
        The Board found that each of the foregoing factors supported its
    decision to approve the transaction involving the Offer and the Merger as
    fair to the stockholders of the Company.
 
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                                   SIGNATURE
 
    After reasonable 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.
 

                               
                                PLENUM PUBLISHING CORPORATION
 
                                By:              /s/ MARTIN E. TASH
                                     -----------------------------------------
                                                Name: Martin E. Tash
                                        Title: PRESIDENT AND CHIEF EXECUTIVE
                                                      OFFICER

 
DATED: July 10, 1998
 
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