SAFETY KLEEN CORP
8-A12B/A, 1998-03-31
BUSINESS SERVICES, NEC
Previous: SAFEGUARD SCIENTIFICS INC ET AL, 10-K, 1998-03-31
Next: SANTA FE FINANCIAL CORP, 10KSB, 1998-03-31



<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C.  20549

                               -----------------

                                  FORM 8-A/A

               FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                   PURSUANT TO SECTION 12(b) OR 12(g) OF THE
                        SECURITIES EXCHANGE ACT OF 1934


                              Safety-Kleen Corp.
- --------------------------------------------------------------------------------
            (Exact name of registrant as specified in its charter)


           Wisconsin                                         39-6090019
- --------------------------------------------------------------------------------
(State of incorporation or organization)                    (IRS Employer
                                                            Identification No.)

One Brinckman Way, Elgin, Illinois                          60123-7857
- --------------------------------------------------------------------------------
     (Address of principal executive offices)               (Zip Code)


If this Form relates to the registration of a class of debt securities and is
effective upon filing pursuant to General Instruction A(c)(1), please check the
following box.   [_]

If this Form relates to the registration of a class of debt securities and is to
become effective simultaneously with the effectiveness of a concurrent
registration statement under the Securities Act of 1933 pursuant to General
Instruction A(c)(2), please check the following box.  [_]


Securities to be registered pursuant to Section 12(b) of the Act:

     Title of each class                 Name of each exchange on which
     to be so registered                 each class is to be registered
     -------------------                 -----------------------------------

Common Stock Purchase Rights             New York Stock Exchange


Securities to be registered pursuant to Section 12(g) of the Act:


 
                                     None
- --------------------------------------------------------------------------------
                               (Title of Class)
<PAGE>
 
Item 1.   Description of Securities.
          ------------------------- 

     On November 20, 1997, Safety-Kleen Corp., a Wisconsin corporation (the
"Company"), entered into an Agreement and Plan of Merger (the "Merger
Agreement") with SK Parent Corp., a Delaware corporation ("Parent"), and SK
Acquisition Corp. a Wisconsin corporation ("Purchaser").  On March 9, 1998,
following the failure of the Merger Agreement to win shareholder approval on
that date, the Board of Directors of the Company terminated the Merger
Agreement.

     On March 11, 1998, the Board of Directors, following an unsuccessful
attempt to negotiate improvements to the unsolicited pending exchange offer of
Laidlaw Environmental Services, Inc. ("Laidlaw Environmental") made pursuant to
the Amended Prospectus dated January 28, 1998 ("Amended Prospectus") of Laidlaw
Environmental, adopted a Third Amendment, dated as of March 11, 1998 (the "Third
Amendment"), to the Rights Agreement, dated as of November 9, 1988 (as amended
by the First Amendment dated August 9, 1990 (the "First Amendment") and the
Second Amendment dated November 20, 1997 ("Second Amendment").  The Third
Amendment provided, among other things, that the commencement or consummation
occurring prior to Midnight, Eastern Standard Time on March 27, 1998, of the
exchange offer contemplated by the Amended Prospectus, on the terms therein or
on terms more favorable to shareholders of the Company (provided that prior to
such consummation, Laidlaw Environmental publicly announces (the "Announcement")
that it will effect the back-end merger contemplated by the Amended Prospectus
with per share consideration at least as favorable as the per share
consideration paid in the exchange offer), will not (i) cause Laidlaw
Environmental, LES Acquisition, Inc. ("LES") or any of their respective
Affiliates or Associates to become an "Acquiring Person" (as defined in the
Rights Agreement), (ii) give rise to a "Distribution Date" (as defined in the
Rights Agreement) or (iii) trigger certain other events specified in the Rights
Agreement.

     On March 16, following further negotiations with Laidlaw Environmental, the
Company entered into an Agreement and Plan of Merger (the "LLE Merger
Agreement"), with Laidlaw Environmental and LES.  In connection with the LLE
Merger Agreement, the Board of Directors of the Company approved a Fourth
Amendment, dated March 15, 1998 ("Fourth Amendment") to the Rights Agreement,
dated as of November 9, 1988 (as amended by the First Amendment, the Second
Amendment, the Third Amendment, and the Fourth Amendment, the "Rights Agreement"
(except where the context otherwise requires)) between the Company and The First
National Bank of Chicago, as Rights Agent.  The Fourth Amendment deletes the
provisions relating to Laidlaw Environmental and LES that had been added by the
Third Amendment, and, instead, provides, among other things, that the execution,
delivery and performance of the LLE Merger Agreement will not cause (i) Laidlaw
Environmental, LES or any of their respective Affiliates or Associates to become
an "Acquiring Person" (as defined in the Rights Agreement), (ii) give rise to a
"Distribution Date" (as defined in the Rights Agreement), or (iii) trigger
certain other events specified in the Rights Agreement.

     The following is a description of the Company's Rights Agreement as
amended.

                                      -1-
<PAGE>
 
     On November 9, 1988, the Board of Directors of the Company declared a
dividend of one common share purchase right ("Right") on each outstanding share
of the Company's Common Stock, $.10 par value per share (the "Common Shares"),
payable to shareholders of record on November 21, 1988 (the "Record Date").
Each Right entitles the holder thereof to buy one Common Share at an exercise
price of $73.00, subject to adjustment.  The terms of the Rights are set forth
in the Rights Agreement.

     Until the earlier to occur of (i) 10 days following a public announcement
that a person or group of affiliated or associated persons (excluding Laidlaw
Environmental, LES and their respective affiliates and associates unless any
such person acquires beneficial ownership of 20% or more of the outstanding
Common Shares other than pursuant to the terms of the LLE Merger Agreement (an
"Acquiring Person")) have acquired beneficial ownership of 20% or more of the
outstanding Common Shares or (ii) 10 business days (or such later date as may be
determined by action of the Board of Directors prior to such time as any person
or group becomes an Acquiring Person) following the commencement of, or
announcement of an intention to make, a tender offer or exchange offer the
consummation of which would result in the beneficial ownership by a person or
group of affiliated or associated persons of 20% or more of such outstanding
Common Shares (the earlier of such dates being called the "Distribution Date"),
the Rights will be evidenced by Common Share certificates.  Notwithstanding the
foregoing, a Distribution Date shall not be deemed to have occurred solely as a
result of (i) the approval, execution or delivery of the LLE Merger Agreement,
or (ii) commencement or consummation, of the transactions contemplated by the
LLE Merger Agreement.

     A person shall not be deemed to have become an "Acquiring Person" for any
purposes if, as determined in good faith by the Board of Directors, he
inadvertently becomes an Acquiring Person and promptly thereafter divests
himself of sufficient number of Common Shares to no longer be an "Acquiring
Person".

     The Rights Agreement provides that, until the Distribution Date, the Rights
will be transferred with and only with the Common Shares.  Until the
Distribution Date (or earlier redemption or expiration of the Rights), new
Common Share certificates issued after the Record Date will contain a notation
incorporating the Rights Agreement by reference.  Until the Distribution Date
(or earlier redemption or expiration of the Rights), the surrender for transfer
of any certificates for Common Shares will also constitute the transfer of the
Rights associated with the Common Shares represented by such certificate.  As
soon as practicable following the Distribution Date, separate certificates
evidencing the Rights ("Right Certificates") will be mailed to holders of record
of the Common Shares as of the close of business on the Distribution Date and
such separate Right Certificates alone will evidence the Rights.

     The Rights are not exercisable until the Distribution Date.  The Rights
will expire on November 21, 1998 (the "Final  Expiration Date"), unless the
Rights are earlier redeemed by the Company, as described below.

                                      -2-
<PAGE>
 
     The Purchase Price payable, and the number of Common Shares or other
securities or property issuable, upon exercise of the Rights are subject to
adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Common
Shares, (ii) upon the grant to holders of the Common Shares of certain rights or
warrants to subscribe for or purchase Common Shares at a price, or securities
convertible into Common Shares with a conversion price, less than the then
current market price of the Common Shares or (iii) upon the distribution to
holders of the Common Shares of evidences of indebtedness or assets (excluding
regular periodic cash dividends paid out of earnings or retained earnings or
dividends payable in Common Shares) or of subscription rights or warrants (other
than those referred to above).  With certain exceptions, no adjustment in the
Purchase Price will be required until cumulative adjustments require an
adjustment of at least 1% in such Purchase Price.  No fractional Common Shares
will be issued and in lieu thereof, an adjustment in cash will be made based on
the market price of the Common Shares on the last trading day prior to the date
of exercise.

     If any person becomes an Acquiring Person, each holder of a Right, other
than Rights beneficially owned by the Acquiring Person (which will be void),
will have the right to receive upon exercise of such Right that number of Common
Shares having a market value of two times the exercise price of the Right.

     In addition, if the Company is acquired in a merger or other business
combination transaction or 50% or more of its consolidated assets or earning
power are sold, proper provision will be made so that each holder of a Right
will thereafter have the right to receive, upon the exercise thereof at the then
current exercise price of the Right, that number of shares of common stock of
the acquiring company which at the time of such transaction will have a market
value of two times the exercise price of the Right.

     Notwithstanding anything in the Rights Agreement to the contrary, holders
of Rights will not have the right to exercise such Rights as set forth in the
immediately preceding two paragraphs, and the Board of Directors of the Company
will not have the right described in the next paragraph, solely as a result of
(i) the approval, execution or delivery of the LLE Merger Agreement, or (ii) the
commencement or consummation of the transactions contemplated by the LLE Merger
Agreement.

     At any time after a person or group becomes an Acquiring Person and prior
to the acquisition by such person or group of 50% or more of the  outstanding
Common Shares, the Board of Directors of the Company may exchange the Rights
(other than Rights owned by such person or group which have become void), in
whole or in part, at an exchange ratio of one Common Share per Right (subject to
adjustment).

     At any time before a person or group becomes an Acquiring Person, the Board
of Directors of the Company may redeem the Rights in whole, but not in part, at
a price of $.01 per Right, subject to adjustment (the "Redemption Price").  The
redemption of the Rights may be made effective at such time, on such basis and
with such conditions as the Board of Directors

                                      -3-
<PAGE>
 
in its sole discretion may establish.  Immediately upon any redemption of the
Rights, the right to exercise the Rights will terminate and the only right of
the holders of the Rights will be to receive the Redemption Price.

     The terms of the Rights may be amended by the Board of Directors of the
Company without the consent of the holders of the Rights, including an amendment
to lower the threshold for exercisability of the Rights from 20% to not less
than the greater of (i) any percentage greater than the largest percentage of
the outstanding Common Shares then known to the Company to be beneficially owned
by any person or group of affiliated or associated persons and (ii) 10%, except
that from and after such time as any person becomes an Acquiring Person no such
amendment may adversely affect the interests of the holders of the Rights.

     Until a Right is exercised, the holder thereof, as such, will have no
rights as a shareholder of the Company, including, without limitation, the right
to vote or to receive dividends.

     The Rights Agreement, dated as of November 9, 1988, between Safety-Kleen
Corp. and The First National Bank of Chicago, as Rights Agent, is filed as
Exhibit 1 to the Company's Registration Statement on Form 8-A dated December 28,
1988.  The First Amendment is filed as Exhibit 1 to the Company's Form 8 dated
August 27, 1990.  The Second Amendment is filed as Exhibit 1.3 to the Company's
Form 8-A/A dated November 20, 1998.  The Third Amendment is filed as Exhibit 1.4
to this Form 8A/A.  The Fourth Amendment is filed as Exhibit 1.5 to this Form
8A/A.  The Board of Directors of the Company adopted a resolution on November
14, 1997 which is described in the Company's Form 8-K dated November 14, 1997.
The foregoing summary description of the Rights does not purport to be complete
and is qualified in its entirety by the reference to such exhibits and Form 8-K,
which are hereby incorporated herein by reference in their entirety.

Item 2.   Exhibits.
          -------- 

     1.1  Rights Agreement, dated as of November 9, 1988, between Safety-Kleen
          Corp. and The First National Bank of Chicago, as Rights Agent
          (incorporated by reference to the Company's Registration Statement on
          Form 8-A dated December 28, 1988).

     1.2  First Amendment, dated as of August 10, 1990, between Safety-Kleen
          Corp. and The First National Bank of Chicago (incorporated by
          reference to the Company's Form 8 dated August 27, 1990 amending the
          Form 8-A dated December 28, 1988).

     1.3  Second Amendment dated as of November 20, 1997 between Safety-Kleen
          Corp. and The First National Bank of Chicago, as Rights Agent.

                                      -4-
<PAGE>
 
     1.4  Third Amendment dated as of March 11, 1997 between Safety-Kleen Corp.
          and the First National Bank of Chicago, as Rights Agent (filed
          herewith).

     1.5  Fourth Amendment, dated as of March 15, 1998, between Safety-Kleen
          Corp. and The First National Bank of Chicago, as Rights Agent (filed
          herewith).

                                      -5-
<PAGE>
 
                                  SIGNATURES


     Pursuant to the requirements of Section 12 of the Securities Exchange Act
of 1934, the registrant has duly caused this registration statement to be signed
on its behalf by the undersigned, thereunto duly authorized.



                                      SAFETY-KLEEN CORP.


                                      /s/ DONALD W. BRINCKMAN
                                      ----------------------------------
                                      Donald W. Brinckman
Dated: March 30, 1998                 Chairman and Chief Executive Officer

                                      -6-
<PAGE>
 
                               INDEX TO EXHIBITS
                               -----------------



Exhibit
- -------

1.1  Rights Agreement, dated as of November 9, 1988, between Safety-Kleen Corp.
     and The First National Bank of Chicago, as Rights Agent (incorporated by
     reference to the Company's Registration Statement on Form 8-A dated
     December 28, 1988).

1.2  First Amendment, dated as of August 10, 1990, between Safety-Kleen Corp.
     and The First National Bank of Chicago (incorporated by reference to the
     Company's Form 8 dated August 27, 1990 amending the Form 8-A dated December
     28, 1988).

1.3  Second Amendment dated as of November 20, 1997 between Safety-Kleen Corp.
     and The First National Bank of Chicago, as Rights Agent.

1.4  Third Amendment dated as of March 11, 1997 between Safety-Kleen Corp. and
     the First National Bank of Chicago, as Rights Agent (filed herewith).

1.5  Fourth Amendment, dated as of March 15, 1998, between Safety-Kleen Corp.
     and The First National Bank of Chicago, as Rights Agent (filed herewith).

<PAGE>

                                                                     EXHIBIT 1.4
 
                      THIRD AMENDMENT TO RIGHTS AGREEMENT
                      -----------------------------------

          THIRD AMENDMENT dated as of March 11, 1998 (the "Third Amendment") to
the Rights Agreement dated as of November 9, 1988, as amended (the "Rights
Agreement"), between Safety-Kleen Corp., a Wisconsin corporation (the
"Company"), and The First National Bank of Chicago, as Rights Agent (the "Rights
Agent").

          Pursuant to Section 27 of the Rights Agreement, the Company and the
Rights Agent may from time to time amend the Rights Agreement in accordance with
Section 27 thereof.  All acts and things necessary to make this Third Amendment
valid and enforceable have been performed and done, including, as required by
Section 27(b) of the Rights Agreement, the delivery by the Company to the Rights
Agent of certified resolutions of the Board of Directors of the Company.  Unless
the context otherwise requires, terms not defined herein have the same meanings
as in the Rights Agreement.

          In consideration of the foregoing and the mutual agreements herein,
the Company and the Rights Agent agree as follows:

          1.  Section 1(a) of the Rights Agreement is hereby amended by deleting
the first sentence of that section and substituting the following therefor:

          "(a) "Acquiring Person" shall mean any Person who or which, together
          with all Affiliates and Associates of such Person, shall be the
          Beneficial Owner of 20% or more of the aggregate number of Common
          Shares of the Company then issued and outstanding, but shall not
          include (i) the Company, (ii) any Subsidiary, (iii) any employee
          benefit plan of the Company or any Subsidiary, (iv) any entity holding
          Common Shares for or pursuant to the terms of any such plan, (v) SK
          Parent Corp., a Delaware corporation ("Parent"), SK Acquisition Corp.,
          a Wisconsin Corp. ("Purchaser"), or any Affiliate or Associate of
          Parent or Purchaser; provided, however, that Parent, Purchaser and the
          Affiliates and Associates of Parent and Purchaser will not be excepted
          from this definition of "Acquiring Person" in the event that any of
          Parent, Purchaser or any Affiliate or Associate of Parent or Purchaser
          becomes the Beneficial Owner of 20% or more of the aggregate number of
          Common Shares of the Company then issued and outstanding other than
          pursuant to the terms of the Agreement and Plan of Merger, dated as of
          November 20, 1997 (the "Merger Agreement"), between the
<PAGE>
 
          Company, Parent and Purchaser or (vi) Laidlaw Environmental Services,
          Inc., ("Laidlaw Environmental"), LES Acquisition, Inc. ("LES
          Acquisition") or any Affiliate or Associate of Laidlaw Environmental
          or LES Acquisition; provided, however, that Laidlaw Environmental, LES
          Acquisition, and the Affiliates and Associates of Laidlaw
          Environmental and LES Acquisition will not be excepted from this
          definition of "Acquiring Person" in the event that any of Laidlaw
          Environmental, LES Acquisition or any Affiliate or Associate of
          Laidlaw Environmental or LES Acquisition becomes the Beneficial Owner
          of 20% or more of the aggregate number of Common Shares of the Company
          then issued and outstanding unless the acquisition by which any such
          person becomes the Beneficial Owner of 20% or more of such Common
          Shares satisfies each of the following requirements: (A) it is
          consummated prior to Midnight, Eastern Standard Time on March 27, 1998
          (B) it is consummated pursuant to either the terms of the Laidlaw
          Environmental Exchange Offer as stated in the Amended Prospectus of
          Laidlaw Environmental dated January 28, 1998 as filed on such date
          ("Amended Prospectus") or terms more favorable to shareholders of the
          Company than the terms of such Amended Prospectus; without limiting
          the generality of the foregoing, the Minimum Condition, as defined in
          the Amended Prospectus, must not have been waived or decreased, and
          the Laidlaw Environmental Offer Consideration, as defined in the
          Amended Prospectus, must not have been diminished and (C) prior to
          such consummation, Laidlaw Environmental has publicly announced (and
          reflected in an appropriate filing with the Securities and Exchange
          Commission) (the "Announcement and Filing") that it will effect the
          Merger, as defined in the Amended Prospectus, with per share
          consideration paid in the Merger that is at least as favorable as the
          per share consideration paid in the acquisition referred to in clause
          (B).

          2.  Section 3(a) of the Rights Agreement is hereby amended by
substituting for the final sentence thereof the following:

          "Notwithstanding anything in this Agreement to the contrary, a
          Distribution Date shall not be deemed to have occurred solely as a
          result of (i) the approval, execution or delivery of the Merger
          Agreement, (ii) the commencement or consummation of the transactions
          contemplated by the Merger Agreement or (iii) the commencement or
          consummation occurring prior to Midnight, Eastern Standard Time on
          March 27, 1998 (accompanied by the Announcement and Filing prior to
          such consummation), of the exchange offer contemplated by the Amended
          Prospectus, on the terms therein or on terms more favorable to
          shareholders of the Company than the terms of the Amended Prospectus;
          without limiting the generality of the foregoing, the Minimum
          Condition, as defined in the Amended Prospectus, must not have been
          waived or decreased, and the Laidlaw Environmental Offer
          Consideration, as defined in the Amended Prospectus, must not have
          been diminished."

                                      -2-
<PAGE>
 
     3.  Section 11(a)(ii) of the Rights Agreement is hereby amended by
substituting for the final sentence thereto the following:

     "Notwithstanding anything in this Agreement to the contrary, an event
     described in this subparagraph (ii) of Section 11(a) shall not be deemed to
     have occurred solely as a result of (i) the approval, execution or delivery
     of the Merger Agreement, (ii) the commencement or consummation of the
     transactions contemplated by the Merger Agreement or (iii) the commencement
     or consummation occurring prior to Midnight, Eastern Standard Time on March
     27, 1998 (accompanied by the Announcement and Filing prior to such
     consummation), of the exchange offer contemplated by the Amended
     Prospectus, on the terms therein or on terms more favorable to shareholders
     of the Company than the terms of the Amended Prospectus; without limiting
     the generality of the foregoing, the Minimum Condition, as defined in the
     Amended Prospectus, must not have been waived or decreased, and the Laidlaw
     Environmental Offer Consideration, as defined in the Amended Prospectus,
     must not have been diminished."

     4.  Section 13(a) of the Rights Agreement is hereby amended by substituting
for the final sentence thereof the following:

     "Notwithstanding anything in this Agreement to the contrary, an event
     described in any of clauses (i), (ii) or (iii) of this Section 13(a) shall
     not be deemed to have occurred solely as a result of (i) the approval,
     execution or delivery of the Merger Agreement, (ii) the commencement or
     consummation of the transactions contemplated by the Merger Agreement or
     (iii) the commencement or consummation occurring prior to Midnight, Eastern
     Standard Time on March 27, 1998 (accompanied by the Announcement and Filing
     prior to such consummation), of the exchange offer contemplated by the
     Amended Prospectus, on the terms therein or on terms more favorable to
     shareholders of the Company than the terms of the Amended Prospectus;
     without limiting the generality of the foregoing, the Minimum Condition, as
     defined in the Amended Prospectus, must not have been waived or decreased,
     and the Laidlaw Environmental Offer Consideration, as defined in the
     Amended Prospectus, must not have been diminished."

     5.  This Third Amendment shall be governed by and construed in accordance
with the laws of the State of Wisconsin applicable to contracts made and
performed entirely within such state.

                                      -3-
<PAGE>
 
     6.  In all respects not inconsistent with this Third Amendment, the Rights
Agreement is hereby ratified, approved and confirmed.  In executing and
delivering this Third Amendment, the Rights Agent shall be entitled to all the
privileges and immunities afforded to the Rights Agent under the Rights
Agreement.

     7.  If any term, provision, covenant or restriction of the Third Amendment
is held by a court of competent jurisdiction or other authority to be invalid,
void or unenforceable, the other terms, provisions, covenants and restrictions
of this Third Amendment, and of the Rights Agreement, shall remain in full force
and effect and shall in no way be affected, impaired or invalidated.

     8.  This Third Amendment may be executed in any number of counterparts,
each of which shall be an original, but all of which shall together constitute
one and the same instrument.

                                      -4-
<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have caused this Third Amendment to
be duly executed and attested, all as of the date first above written.

                              SAFETY-KLEEN CORP.

                              By:
                                 ------------------------------


                              THE FIRST NATIONAL BANK OF CHICAGO

                              By:
                                 --------------------------------  

                                      -5-

<PAGE>

                                                                     EXHIBIT 1.5
 
                      FOURTH AMENDMENT TO RIGHTS AGREEMENT
                      ------------------------------------

     FOURTH AMENDMENT dated as of March 15, 1998 (the "Fourth Amendment") to the
Rights Agreement dated as of November 9, 1988, as amended (the "Rights
Agreement"), between Safety-Kleen Corp., a Wisconsin corporation (the
"Company"), and The First National Bank of Chicago, as Rights Agent (the "Rights
Agent").

     Pursuant to Section 27 of the Rights Agreement, the Company and the Rights
Agent may from time to time amend the Rights Agreement in accordance with
Section 27 thereof.  All acts and things necessary to make this Fourth Amendment
valid and enforceable have been performed and done, including, as required by
Section 27(b) of the Rights Agreement, the delivery by the Company to the Rights
Agent of certified resolutions of the Board of Directors of the Company.  Unless
the context otherwise requires, terms not defined herein have the same meanings
as in the Rights Agreement.

     In consideration of the foregoing and the mutual agreements herein, the
Company and the Rights Agent agree as follows:

     1.  Section 1(a) of the Rights Agreement is hereby amended by deleting the
first sentence of that section and substituting the following therefor:

     "(a)  "Acquiring Person" shall mean any Person who or which, together with
     all Affiliates and Associates of such Person, shall be the Beneficial Owner
     of 20% or more of the aggregate number of Common Shares of the Company then
     issued and outstanding, but shall not include (i) the Company, (ii) any
     Subsidiary, (iii) any employee benefit plan of the Company or any
     Subsidiary, (iv) any entity holding Common Shares for or pursuant to the
     terms of any such plan, (v) SK Parent Corp., a Delaware corporation
     ("Parent"), SK Acquisition Corp., a Wisconsin Corp. ("Purchaser"), or any
     Affiliate or Associate of Parent or Purchaser; provided, however, that
     Parent, Purchaser and the Affiliates and Associates of Parent and Purchaser
     will not be excepted from this definition of "Acquiring Person" in the
     event that any of Parent, Purchaser or any Affiliate or Associate of Parent
     or Purchaser becomes the Beneficial Owner of 20% or more of the aggregate
     number of Common Shares of the Company then issued and
<PAGE>
 
     outstanding other than pursuant to the terms of the Agreement and Plan of
     Merger, dated as of November 20, 1997 (the "Merger Agreement"), between the
     Company, Parent and Purchaser or (vi) Laidlaw Environmental Services, Inc.,
     ("Laidlaw Environmental"), LES Acquisition, Inc. ("LES Acquisition") or any
     Affiliate or Associate of Laidlaw Environmental or LES Acquisition;
     provided, however, that Laidlaw Environmental, LES Acquisition, and the
     Affiliates and Associates of Laidlaw Environmental and LES Acquisition will
     not be excepted from this definition of "Acquiring Person" in the event
     that any of Laidlaw Environmental, LES Acquisition or any Affiliate or
     Associate of Laidlaw Environmental or LES Acquisition becomes the
     Beneficial Owner of 20% or more of the aggregate number of Common Shares of
     the Company then issued and outstanding other than pursuant to the terms of
     the Agreement and Plan of Merger, dated as of March 16, 1998 ("LLE Merger
     Agreement"), among the Company, Laidlaw Environmental and LES Acquisition.

     2.   Section 3(a) of the Rights Agreement is hereby amended by substituting
for the final sentence thereof the following:

     "Notwithstanding anything in this Agreement to the contrary, a Distribution
     Date shall not be deemed to have occurred solely as a result of (i) the
     approval, execution or delivery of the Merger Agreement, (ii) the
     commencement or consummation of the transactions contemplated by the Merger
     Agreement, (iii) the approval, execution or delivery of the LLE Merger
     Agreement, or (iv) the commencement or consummation of the transactions
     contemplated by the LLE Merger Agreement.

     3.   Section 11(a)(ii) of the Rights Agreement is hereby amended by
substituting for the final sentence thereof the following:

     "Notwithstanding anything in this Agreement to the contrary, an event
     described in this subparagraph (ii) of Section 11(a) shall not be deemed to
     have occurred solely as a result of (i) the approval, execution or delivery
     of the Merger Agreement, (ii) the commencement or consummation of the
     transactions contemplated by the Merger Agreement, (iii) the approval,
     execution or delivery of the LLE Merger Agreement, or (iv) the commencement
     or consummation of the transactions contemplated by the LLE Merger
     Agreement.

     4.   Section 13(a) of the Rights Agreement is hereby amended by
substituting for the final sentence thereof the following:

                                      -2-
<PAGE>
 
     "Notwithstanding anything in this Agreement to the contrary, an event
     described in any of clauses (i), (ii) or (iii) of this Section 13(a) shall
     not be deemed to have occurred solely as a result of (i) the approval,
     execution or delivery of the Merger Agreement, (ii) the commencement or
     consummation of the transactions contemplated by the Merger Agreement,
     (iii) the approval, execution or delivery of the LLE Merger Agreement, or
     (iv) the commencement or consummation of the transactions contemplated by
     the LLE Merger Agreement.

     5.   This Fourth Amendment shall be governed by and construed in accordance
with the laws of the State of Wisconsin applicable to contracts made and
performed entirely within such state.

     6.   In all respects not inconsistent with this Fourth Amendment, the
Rights Agreement is hereby ratified, approved and confirmed.  In executing and
delivering this Fourth Amendment, the Rights Agent shall be entitled to all the
privileges and immunities afforded to the Rights Agent under the Rights
Agreement.

     7.   If any term, provision, covenant or restriction of the Fourth
Amendment is held by a court of competent jurisdiction or other authority to be
invalid, void or unenforceable, the other terms, provisions, covenants and
restrictions of this Fourth Amendment, and of the Rights Agreement, shall remain
in full force and effect and shall in no way be affected, impaired or
invalidated.

     8.   This Fourth Amendment may be executed in any number of counterparts,
each of which shall be an original, but all of which shall together constitute
one and the same instrument.

                                      -3-
<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have caused this Fourth Amendment to
be duly executed and attested, all as of the date first above written.

                              SAFETY-KLEEN CORP.

                              By:
                                 --------------------------------  

                              THE FIRST NATIONAL BANK OF CHICAGO

                              By:
                                 --------------------------------    


                                      -4-


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission