UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                   FORM 8-K/A
                                 CURRENT REPORT
     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
      Date of Report (Date of earliest event reported): September 28, 2021
                        Pioneer Natural Resources Company
             ------------------------------------------------------
             (Exact name of Registrant as specified in its charter)
          Delaware                    1-13245                75-2702753
- ----------------------------        ------------        -------------------
(State or other jurisdiction        (Commission          (I.R.S. Employer
     of incorporation)              File Number)        Identification No.)
5205 N. O'Connor Blvd., Suite 900, Irving, Texas                75039
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    (Address of principal executive offices)                 (Zip Code)
                                 (972) 444-9001
              ----------------------------------------------------
              (Registrant's telephone number, including area code)
                                 Not applicable
          -------------------------------------------------------------
          (Former name or former address, if changed since last report)
Check  the  appropriate  box  below  if the  Form  8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the registrant under any of the
following provisions:
[ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR
    230.425)
[ ] Soliciting material pursuant  to Rule  14a-12 under the Exchange Act (17 CFR
    240.14a-12)
[ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange
    Act (17 CFR 240.14d-2(b))
[ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange
    Act (17 CFR 240.13e-4(c))

                        PIONEER NATURAL RESOURCES COMPANY
                                TABLE OF CONTENTS
                                                                      Page
Item 1.01.  Entry into a Material Definitive Agreement.............     3
Item 9.01.  Financial Statements and Exhibits
            (c)   Exhibits.........................................     3
Signature..........................................................     4
Exhibit Index......................................................     5
                                       2

                        PIONEER NATURAL RESOURCES COMPANY
Item 1.01.   Entry into a Material Definitive Agreement
     On September 28, 2004,  Pioneer Natural  Resources  Company (the "Company")
issued the First Supplemental Indenture dated September 28, 2021 with respect to
the Evergreen Resources,  Inc. ("Evergreen")  indenture dated December 18, 2001,
relating to  Evergreen's  4.75%  Senior  Convertible  Notes due 2021 (the "4.75%
Notes")  assumed by the  Company in  conjunction  with the  Evergreen  merger on
September  28, 2004.  The First  Supplemental  Indenture  is attached  hereto as
exhibit 4.1. This Form 8-K/A amends the First  Supplemental  Indenture  filed as
exhibit 4.6 to the Company's Form 8-K dated September 28, 2004.
Item 9.01.   Financial Statements and Exhibits
       (c)   Exhibits
        4.1  First Supplemental Indenture  dated as of September 28, 2004, among
             the Company, Evergreen and Wachovia Bank,  National Association (as
             successor to First Union National Bank),  as trustee,  with respect
             to the indenture dated as of December 18, 2001, among Evergreen and
             First Union National Bank, as trustee, relating to the 4.75% Notes.
                                       3

                       PIONEER NATURAL RESOURCES COMPANY
                               S I G N A T U R E
Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.
                               PIONEER NATURAL RESOURCES COMPANY
Date:   November 4, 2021       By:    /s/ Richard P. Dealy
                                    --------------------------------------------
                                    Richard P. Dealy
                                    Vice President and Chief Accounting Officer
                                       4

                       PIONEER NATURAL RESOURCES COMPANY
                                 EXHIBIT INDEX
Exhibit No.             Description
- -----------             -----------
  4.1(a)                First Supplemental Indenture  dated as  of September 28,
                        2004,  among the Company,  Evergreen and  Wachovia Bank,
                        National  Association   (as  successor  to  First  Union
                        National  Bank),  as  trustee,   with  respect  to   the
                        indenture dated as of December 18, 2001, among Evergreen
                        and First Union National Bank,  as trustee,  relating to
                        the 4.75% Notes.
- -------------
(a) filed herewith
                                       5

                                                                     EXHIBIT 4.1
                          FIRST SUPPLEMENTAL INDENTURE
     THIS FIRST  SUPPLEMENTAL  INDENTURE  dated as of  September  28, 2021 (this
"Supplemental  Indenture"),  is  entered  into  by  and  among  Pioneer  Natural
Resources Corporation, a Delaware corporation ("Pioneer"),  Evergreen Resources,
Inc.,  a Colorado  corporation  (the  "Company"),  and Wachovia  Bank,  National
Association,  the  successor to First Union  National  Bank, a national  banking
association,  as trustee (the "Trustee").  Capitalized terms used herein and not
otherwise  defined  have the  meanings  set forth in the  Indenture  referred to
below.
                                    RECITALS
    A.   The Company  has heretofore  executed and  delivered to the  Trustee an
indenture  dated as of December 18, 2021 (the  "Indenture"),  providing  for the
issuance  of  4.75%  Senior  Convertible  Notes  due  2021 of the  Company  (the
"Securities").
    B.   The Conversion Price  is equal to  $25.00,  pursuant to the two-for-one
split of Evergreen Common Stock (as defined below) effective September 16, 2003.
    C.   The Company has  entered into an  Agreement and Plan of Merger dated as
of May 3,  2004,  by  and  among  Pioneer,  BC  Merger  Sub,  Inc.,  a  Colorado
corporation and a wholly-owned  subsidiary of Pioneer  ("Merger  Sub"),  and the
Company (the  "Merger  Agreement"),  providing  for (i) the merger of Merger Sub
with and into the Company with the Company as the  surviving  corporation  and a
wholly-owned subsidiary of Pioneer and (ii) immediately  thereafter,  the merger
of the Company with and into Pioneer Evergreen Properties,  LLC, a Texas limited
liability  company  ("LLC  Sub"),  with LLC Sub as the  surviving  entity  and a
wholly-owned subsidiary of Pioneer (collectively, the "Merger").
    D.   As a result of the Merger, Pioneer will issue a number of shares of its
common stock, par value $0.01 per share and related shareholder rights ("Pioneer
Common Stock"), equal to approximately 21% of the shares of Pioneer Common Stock
outstanding  immediately prior to the Merger and pay approximately  $865,000,000
in cash, subject to adjustments as provided in the Merger Agreement, in exchange
for shares of common  stock,  no par value,  of the Company  ("Evergreen  Common
Stock").
    E.   Pursuant to Section 2.1(d) of the Merger Agreement, after the effective
time of the merger of Merger Sub and Evergreen  (the "Merger  Effective  Time"),
each Holder of the Securities will have the right to receive, upon conversion of
the  Securities in accordance  with the Indenture,  at the Conversion  Price and
instead of one share of Evergreen  Common Stock that such Holder  previously was
entitled to receive upon conversion,  (i) $19.50 in cash, without interest, plus
(ii)  $0.48  in  cash,   without   interest   (representing   the  Kansas   Sale
Consideration, as defined in the Merger Agreement), and (iii) 0.58175 of a share
of Pioneer Common Stock (the "Evergreen Consideration Unit").
    F.   Pursuant to Section 4.11 of the Indenture,  as a condition precedent to
any  merger  effecting  a change  in the kind and  amount  of  shares  and other
property issuable upon the conversion of the Securities, the Company and Pioneer

shall execute and deliver to the Trustee a supplemental indenture providing that
the Holder of each  Security  then  outstanding  shall have the right to convert
such Security into such other  securities and property  receivable in the merger
by a holder of Evergreen Common Stock.
    G.   In accordance with Section 11.1(a) of the Indenture the Company and the
Trustee may amend or supplement  the Indenture or the  Securities to comply with
Section 4.11 without notice to or consent of any Securityholder.
    H.   The Company and Pioneer desire and have  requested the Trustee to enter
into this  Supplemental  Indenture  for the purpose of amending the Indenture to
provide that, upon conversion of the Securities under the Indenture, a Holder of
Securities will receive one Evergreen  Consideration  Unit in lieu of each share
of  Evergreen  Common  Stock to which  such  Holder  otherwise  would  have been
entitled upon conversion.
    I.   Each of the  Company and  Pioneer has duly authorized the execution and
delivery of this Supplemental Indenture.
                                   AGREEMENTS
     NOW,  THEREFORE,  in  consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the parties
hereto  hereby  covenant  and agree for the equal  and  ratable  benefit  of the
Holders of the Securities as follows:
     Section 1.   Confirmation of  Original  Indenture.  Except  as  mended  and
supplemented hereby, the Indenture is hereby ratified,  confirmed and reaffirmed
in all respects.  The Indenture and this  Supplemental  Indenture shall be read,
taken and construed as one and the same instrument.
     Section 2.   Definitions. Section 1.1 of the Indenture is hereby amended as
follows:
     (a) The  definition  of "Conversion Rate" is hereby amended and restated in
its entirety to read as follows:
                  "Conversion Rate"  means the number of Evergreen Consideration
         Units  into  which  each  $1,000  principal  amount  of  Securities  is
         convertible,  which is determined by  dividing $1,000 by the Conversion
         Price at such time, rounded to three decimal places  (rounded up if the
         fourth decimal place thereof is 5 or  more and otherwise rounded down).
         The Conversion Rate at September 28, 2004, is 40 ($1,000 / $25.00).
     (b) The definition of  "Conversion Value" is hereby amended and restated in
its entirety to read as follows:
                  "Conversion Value" of a  Security as of any date means the sum
         of (A) the product of the Sale Price of a share of Pioneer Common Stock
         times  the number  of shares  of Pioneer  Common Stock  into which  the
         Security could  then  be  converted  (assuming  that  the  Security was
         convertible as of such date) plus (B) the product of the Cash Component
                                       2

         times  the  number of  Evergreen  Consideration  Units  into  which the
         Security  could  then be  converted  (assuming  that  the Security  was
         convertible as of such date).
     (c) The definition of "Ex-Dividend Time" is  hereby amended and restated in
its entirety to read as follows:
                  "Ex-Dividend Time"  means,  with respect  to any  issuance  or
         distribution on shares of Pioneer Common Stock, the first date on which
         the shares of Pioneer  Common Stock trade  regular way on the principal
         securities  market on which the shares of Pioneer Common Stock are then
         traded without the right to receive such issuance or distribution.
     (d) The definition of "Record Date" is hereby  amended and  restated in its
entirety to read as follows:
                  "Record  Date"  shall  mean,  with  respect  to any  dividend,
         distribution  or other  transaction  or event  in which  the holders of
         shares  of Pioneer  Common Stock  have the  right to  receive any cash,
         securities or other property or in which the  shares of  Pioneer Common
         Stock (or other applicable security) is exchanged for or converted into
         any combination of cash,  securities or other property,  the date fixed
         for  determination  of  stockholders  entitled  to  receive  such cash,
         securities or other property  (whether such date is fixed by  the Board
         of Directors or by statute, contract or otherwise).
     (e) The  definition of  "Sale Price" is  hereby amended and restated in its
entirety to read as follows:
         "Sale Price" of the shares of Pioneer Common Stock on any date means:
     (1) the closing  per share  sale price  (or, if  no closing  sale price  is
         reported, the average of the bid and ask prices or, if more than one in
         either case,  the average of the average bid and average ask prices) on
         such date as reported in the  composite transactions  for the principal
         United States securities exchange on which the shares of Pioneer Common
         Stock are traded, or
     (2) if Pioneer Common Stock  is not  listed on a  United States national or
         regional securities exchange,  as reported by the  National Association
         of Securities Dealers Automated Quotation System or its successors.
     (f) The definition of "Cash Component" is hereby added to the Indenture and
shall read as follows:
         "Cash Component" means the cash portion of the  Evergreen Consideration
      Unit, which is $19.98, without interest."
     (g) The definition of "Evergreen Consideration Unit" is hereby added to the
Indenture and shall read as follows:
                                       3

         "Evergreen Consideration Unit"  means  0.58175  of a  share of  Pioneer
      Common Stock plus the Cash Component.
      (h) The  definition of  "Pioneer Common  Stock" is  hereby  added  to  the
Indenture and shall read as follows:
          "Pioneer Common Stock"  means  the  common  stock of  Pioneer  Natural
      Resources Company, a Delaware corporation ("Pioneer"), $0.01 par value, as
      it  exists  on  the date  of this  Indenture,  as heretofore  amended  and
      supplemented,  and any shares  of any class or classes of Capital Stock of
      Pioneer resulting from any  reclassification or  reclassifications thereof
      and which have no preference in respect of dividends or of amounts payable
      in the event of any voluntary or  involuntary liquidation,  dissolution or
      winding-up  of the  Company and  which are  not subject  to  redemption by
      Pioneer; provided, however,  that if at any time  there shall be more than
      one such resulting class,  the shares of  each such class then so issuable
      on conversion of Securities shall be substantially in the proportion which
      the total  number  of  shares  of  such  class  resulting  from  all  such
      reclassifications bears  to the total number of shares of all such classes
      resulting from all such reclassifications."
      Section 3.   Conversion. Article IV of the Indenture is hereby amended and
restated in its entirety to read as set forth on Annex A hereto.
      Section 4.   Conversion  Arrangement on  Repurchase.  Section  5.14 of the
Indenture  is hereby  amended  and  restated in its entirety to read as follows:
          Section 5.14    Conversion Arrangement on Repurchase
          Any Securities required to be repurchased under this Article V, unless
      surrendered  for conversion  before the  close of business on the Optional
      Repurchase Date,  may be deemed to be  purchased from  the Holders of such
      Securities for an amount  in cash  not less  than the  Optional Repurchase
      Price, by one or more investment bankers or other purchasers who may agree
      with the Company to purchase  such Securities from the Holders, to convert
      them into shares of Pioneer Common Stock or  Evergreen Consideration Units
      and to make payment for such  Securities to the  Trustee in trust for such
      Holders.
      Section 5.   Waiver of Defaults and Events of Default.  Section 8.4 of the
Indenture  is hereby  amended and  restated in its entirety to read as follows:
          Section 8.4      Waiver of Defaults and Events of Default
          Subject  to  Sections  8.7  and  11.2,  the  Holders of a  majority in
      principal amount  of the  Securities  then  outstanding  by notice  to the
      Trustee  may waive  an  existing  default or  Event  of  Default  and  its
      consequence,  except a default  or Event  of Default in the payment of the
      principal of or  interest  on any  Security,  a failure by the  Company to
      convert any  Securities into  Evergreen Consideration Units or any default
      or Event of Default  in respect of any provision  of this Indenture or the
      Securities  which,  under  Section  11.2,  cannot be  modified or  amended
      without  the consent  of the  Holder  of each  Security  affected.  When a
      default or Event of Default is waived, it is cured and ceases.
                                       4

      Section 6.   Change of Control.  The definition of the "Change of Control"
in Section 12.1 of the  Indenture is hereby  amended as follows:
      (a)   Clause (4) of Section 12.1  is hereby  amended  and restated  in its
entirety to read as follows:
            (4) the closing price  (determined in accordance with Section 4.6(d)
       of this Indenture)  of Pioneer  Common Stock  for any  five  Trading Days
       within:
                (i) the  period of  the ten  Trading Days  immediately after the
             later of  the Change  in Control  or the public announcement of the
             Change in Control, in the  case of a  Change in  Control  resulting
             solely from a Change in Control under Section 12.1(a)(1), or
                (ii) the period of the ten  Trading Days  immediately  preceding
             the Change in Control, in the case of a Change in Control resulting
             from a Change in Control under Section 12.1(a)(2) or (3),
             plus the Cash Component is at least equal to 105% of the Conversion
             Price in effect on such Trading Day plus the Cash Component; or
      (b)   Clause (5) of  Section 12.1  is hereby  amended and  restated in its
            entirety to read as follows:
                 (5) in  the  case  of  a merger  or consolidation,  all of  the
            consideration  excluding cash  payments for fractional shares in the
            merger or consolidation  constituting the Change in Control consists
            of  common  stock  traded on a  United  States  national  securities
            exchange or quoted on the NNM (or which, will be so traded or quoted
            when issued  or exchanged in connection with such Change in Control)
            and as a result  of such  transaction or transactions the Securities
            become  convertible  solely into  such common  stock plus  the  Cash
            Component.
      Section 7.   Effect  of  Change in  Control  Repurchase  Notice.  The last
sentence  of the first  paragraph  of Section  12.2 of the  Indenture  is hereby
amended and restated in its entirety to read as follows:
                 Securities in  respect of  which a Change in Control Repurchase
            Notice has  been given  by the  Holder thereof  may not be converted
            into  Evergreen  Consideration  Units on  or after  the  date of the
            delivery of such  Change in  Control  Repurchase Notice  unless such
            Change  in   Control  Repurchase   Notice  has  first  been  validly
            withdrawn.
      Section 8.   Form of 4.75% Senior Convertible Notes Due 2021.
      (a)   The last  sentence of the second paragraph of Section 1  of the form
of Security is hereby amended and restated as follows:
                                       5

                 Except as provided  in this  Security or  in the Indenture,  no
            adjustments  in  respect of  payments  of  interest  (including  for
            conversion on any dividend or  distributions or interest  (including
            Contingent Interest)) on any Security  surrendered for conversion on
            any  dividend or  distributions or  interest  (including  Contingent
            Interest) on Pioneer Common Stock or the Cash Component  issued upon
            conversion shall be made upon the conversion of any Security.
      (b)   Section 8 of the form of  Security is hereby amended and restated in
its entirety to read as set forth on Annex B hereto.
      (c)   Section 9 of the form of Security is hereby  amended and restated in
its entirety to read as follows:
                 9.  Conversion Arrangement on Call for Redemption
            Any  Securities  called  for  redemption,   unless  surrendered  for
            conversion  before  the  close  of  business  on  the  Business  Day
            immediately  preceding  the Redemption  Date,  may be  deemed  to be
            purchased  from the  Holders of  such Securities  at an  amount  not
            less than the Redemption Price, together with  accrued  interest, if
            any, to, but not including,  the  Redemption  Date,  by one  or more
            investment  bankers  or other  purchasers  who may  agree  with  the
            Company to  purchase  such Securities from the  Holders,  to convert
            them into Pioneer Common  Stock or Evergreen Consideration Units and
            to make payment for such Securities to the Paying Agent in trust for
            such Holders.
      Section 9.   Wachovia Bank, National  Association. All references to First
Union National Bank,  a national banking  association,  in the Indenture and the
Security are hereby changed to "Wachovia Bank, National Association."
      Section 10.  Conversion  Notice.  The  form of Conversion  Notice for  the
Security is hereby amended  and restated in its entirety to read as set forth on
Annex C hereto.
      Section 11.  Miscellaneous.
      (a) Execution of  Supplemental Indenture.  This Supplemental  Indenture is
executed and  shall be construed  as an  indenture supplemental to the Indenture
and, as provided in the Indenture,  this Supplemental  Indenture forms a part of
the Indenture.
      (b) NEW  YORK LAW TO GOVERN.  THE INTERNAL  LAW OF  THE STATE  OF NEW YORK
SHALL GOVERN AND BE  USED TO CONSTRUE THIS  SUPPLEMENTAL  INDENTURE BUT  WITHOUT
GIVING  EFFECT TO  APPLICABLE  PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.
      (c) Counterparts.  The  parties may  sign  any  number of  copies of  this
Supplemental  Indenture. Each signed copy shall be an original,  but all of them
together represent the same agreement.
                                       6

      (d) Effect of Headings.  The Section headings  herein are for  convenience
only and shall not affect the construction hereof.
      (e) The Trustee.  The  Trustee  shall  not be  responsible in  any  manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals  contained  herein,  all of which
recitals are made solely by Pioneer and the Company.
                  [Remainder of page intentionally left blank]
                                       7

     IN WITNESS  WHEREOF,  the parties  hereto  have  caused  this  Supplemental
Indenture to be duly executed as of the date first above written.
     Dated:  September 28, 2021
                                            EVERGREEN RESOURCES, INC.
                                            By: /s/ Richard P. Dealy
                                               ---------------------------------
                                               Name: Richard P. Dealy
                                               Title: Vice President
                                            PIONEER NATURAL RESOURCES COMPANY
                                            By: /s/ Richard P. Dealy
                                              ----------------------------------
                                               Name: Richard P. Dealy
                                               Title: Vice President
                                            WACHOVIA BANK, NATIONAL ASSOCIATION,
                                             as Trustee
                                            By: /s/ Doug Milner
                                               ---------------------------------
                                               Authorized Signatory
               Signature Page to the First Supplemental Indenture
                        (4.75% Senior Convertible Notes)

                                     ANNEX A
                                   ARTICLE IV
                                   CONVERSION
Section 4.1     Conversion Privilege
     (a)  Subject to and upon compliance with the provisions of this Article, at
the option of the Holder,  any Security or any portion of the  principal  amount
thereof  which  is an  integral  multiple  of  $1,000  may be  converted  at the
principal  amount  thereof,   or  of  such  portion   thereof,   into  Evergreen
Consideration Units, which include duly authorized, fully paid and nonassessable
shares  of  Pioneer  Common  Stock,  at  the  Conversion  Price,  determined  as
hereinafter provided, in effect at the time of conversion:
                 (i) during any Conversion Period, if the Sale Price of 0.58175
          shares of Pioneer Common Stock for at least 20 Trading Days in the 30
          consecutive  Trading  Day  period  ending  on  the  first  day  of the
          Conversion Period plus the  Cash Component  was more than  110% of the
          Conversion Price on that thirtieth Trading Day;
                 (ii) during  the  five  Trading  Day  period  following  any 10
          consecutive  Trading Day  period in  which the  average of the Trading
          Prices for the Security for that 10  Trading Day  period was less than
          105% of the  average Conversion  Value for  the Security  during  that
          period;
                 (iii) during any period in  which the  Securities are  rated by
          Moody's or Standard & Poor's and the  credit rating initially assigned
          to the Securities by either Moody's or Standard & Poor's is reduced by
          two or more ratings levels; provided,  however, that the Company shall
          have no obligation to have the Securities rated;
                 (iv) if the Company has  called the Security for redemption, at
          any  time prior  to  the  close of  business on  the day  that is  two
          Business Days prior to the Redemption Date, even if the Securities are
          not otherwise convertible at that time; or
                 (v) upon the occurrence of the corporate transactions specified
in clause (b) of this Section 4.1.
     The Company shall  determine on a daily basis whether the Security shall be
convertible as a result of the occurrence of an event specified in clause (i) or
clause  (ii) above and, if the  Security  shall be so  convertible,  the Company
shall  promptly  deliver to the Trustee  written  notice  thereof.  Whenever the
Security  shall become  convertible  pursuant to Section 4.1, the Company or, at
the Company's written request, the Trustee in the name and at the expense of the
Company, shall notify the Holders of the event triggering such convertibility in
the manner provided in Section 4.2, and the Company shall also publicly announce
such  information  and publish it on the Company's web site. Any notice so given
shall be  conclusively  presumed  to have been duly  given,  whether  or not the
Holder receives such notice.
                                      A-1

     (b)   In addition, in the event that:
                  (i) (A)  Pioneer  distributes  to  all  holders  of  shares of
           Pioneer Common Stock rights  or warrants entitling them (for a period
           expiring  within 60 days of the Record Date for such distribution) to
           subscribe for or  purchase shares of Pioneer Common Stock, at a price
           per share less than the  Trading Price of Pioneer Common Stock on the
           Business  Day   immediately  preceding  the   announcement  of   such
           distribution,  (B)  Pioneer  distributes to  all holders of shares of
           Pioneer Common Stock, cash or other assets, debt securities or rights
           or warrants to purchase  its securities,  where the Fair Market Value
           (as  determined  by the  Board  of  Directors  of  Pioneer)  of  such
           distribution  per share of Pioneer  Common Stock  exceeds 10%  of the
           Trading Price of a  share of Pioneer Common Stock on the Business Day
           immediately preceding the  date of declaration  of such distribution,
           or (C) a Change in Control of Pioneer occurs, then, in each case, the
           Security may  be surrendered for conversion at  any time on and after
           the date  that the Company gives notice to the Holders of such right,
           which shall be not  less than  20 days prior to  the Ex-Dividend Time
           for such distribution, in the case of  (A) or (B),  or within 30 days
           after the  occurrence of the  Change in  Control, in the case of (C),
           until  the  earlier  of the  close  of  business  on the Business Day
           immediately  preceding  the  Ex-Dividend  Time  or  the  date Pioneer
           announces that such distribution will not take place,  in the case of
           (A) or (B), or the earlier of 30 days after the Company's delivery of
           the Change in Control Repurchase Notice or the date Pioneer announces
           that the Change in Control will not take place, in the case of (C),
           or
                  (ii)  Pioneer  consolidates  with   or  merges  into   another
           corporation,  or  is a  party to  a binding  share exchange  pursuant
           to which  the  shares of  Pioneer  Common  Stock  would be  converted
           into  cash,  securities or  other  property as  set forth in  Section
           4.11 hereof,  then the  Security may  be  surrendered for  conversion
           at any time from  and after the date which  is 15  days prior  to the
           date  announced by  Pioneer  as the  anticipated  effective  time  of
           such  transaction  until 15  days  after  the  actual  date  of  such
           transaction.
     The  Conversion  Rate, at any time,  shall equal (A) $1,000  divided by the
Conversion  Price at such time,  rounded to three decimal places  (rounded up if
the fourth decimal place thereof is 5 or more and otherwise rounded down).
     Notwithstanding  the  foregoing,  if such Security is called for redemption
pursuant to Article III or  submitted or presented  for  repurchase  pursuant to
Articles  V or XII,  such  conversion  right  shall  terminate  at the  close of
business on the second Business Day immediately  preceding the Redemption  Date,
Optional  Repurchase Date or Change in Control  Repurchase Date, as the case may
be, for such Security or such earlier date as the Holder  presents such Security
for  redemption or for purchase  (unless the Company shall default in making the
Redemption  Price,  Optional  Repurchase  Price or Change in Control  Repurchase
Price payment when due, in which case the  conversion  right shall  terminate at
the close of  business  on the date such  default is cured and such  Security is
redeemed or  purchased,  as the case may be). If such  Security is  submitted or
                                      A-2

presented  for  purchase  pursuant  to  Article  III  and is  then  subsequently
withdrawn,  such conversion right shall no longer be terminated,  and the Holder
of such  Security  may convert such  Security  pursuant to this Section 4.1. The
number of Evergreen  Consideration  Units issuable upon conversion of a Security
shall be determined by dividing the principal  amount of the Security or portion
thereof  surrendered  for  conversion by the  Conversion  Price in effect on the
Conversion  Date.  The  Conversion  Price  is set  forth in  paragraph  8 of the
Securities and is subject to adjustment as provided in this Article IV.
     Provisions of this  Indenture that apply to conversion of all of a Security
also apply to conversion of a portion of a Security.
     A  Security  in  respect  of  which a  Holder  has  delivered  an  Optional
Repurchase  Notice  pursuant  to Section  5.1 or a Change in Control  Repurchase
Notice  pursuant  to Section  12.1(c)  exercising  the option of such  Holder to
require the Company to purchase  such  Security  may be  converted  only if such
Optional  Repurchase Notice or Change in Control  Repurchase Notice, as the case
may be, is withdrawn  by a written  notice of  withdrawal  delivered to a Paying
Agent prior to the close of business on the Business Day  immediately  preceding
the Optional  Repurchase Date or Change in Control  Repurchase Date, as the case
may be, in accordance with Sections 5.9 or 12.2, respectively.
     A Holder of Securities is not entitled to any rights of a holder of Pioneer
Common Stock until such Holder has  converted its  Securities to Pioneer  Common
Stock,  and only to the extent such Securities are deemed to have been converted
into Pioneer Common Stock pursuant to this Article IV.
Section 4.2    Conversion Procedure
     To convert a Security,  a Holder must (a) complete  and  manually  sign the
conversion  notice on the back of the  Security  and  deliver  such  notice to a
Conversion  Agent, (b) surrender the Security to a Conversion Agent, (c) furnish
appropriate  endorsements and transfer documents if required by a Registrar or a
Conversion Agent, and (d) pay any transfer or similar tax, if required. The date
on which the  Holder  satisfies  all of those  requirements  is the  "Conversion
Date." As soon as  practicable  after the  Conversion  Date,  the Company  shall
deliver to the Holder through a Conversion Agent a certificate for the number of
whole shares of Pioneer Common Stock issuable upon the conversion,  cash in lieu
of any fractional  shares  pursuant to Section 4.3, and the Cash Component times
the number of Evergreen  Consideration Units (or fractions thereof) payable upon
such conversion. Anything herein to the contrary notwithstanding, in the case of
Global  Securities,  conversion notices may be delivered and such Securities may
be surrendered for conversion in accordance with the Applicable Procedures as in
effect from time to time.
     The person in whose name Pioneer  Common Stock  certificate  is  registered
shall be deemed to be a stockholder of record on the Conversion Date;  provided,
however,  that no  surrender  of a Security on any date when the stock  transfer
books of Pioneer shall be closed shall be effective to constitute  the person or
persons  entitled  to  receive  the  shares of  Pioneer  Common  Stock upon such
conversion  as the record  holder or holders  of such  shares of Pioneer  Common
                                      A-3

Stock on such date,  but such  surrender  shall be effective to  constitute  the
person or persons entitled to receive such shares of Pioneer Common Stock as the
record  holder or holders  thereof for all  purposes at the close of business on
the next  succeeding day on which such stock transfer books are open;  provided,
further,  that such conversion shall be at the Conversion Price in effect on the
Conversion  Date as if the stock  transfer books of Pioneer had not been closed.
Upon  conversion of a Security,  such person shall no longer be a Holder of such
Security.  No payment or adjustment will be made for dividends or  distributions
on shares of Pioneer Common Stock issued upon conversion of a Security.
     Securities so  surrendered  for conversion (in whole or in part) during the
period from the close of  business on any regular  record date to the opening of
business on the next succeeding  interest payment date (excluding  Securities or
portions  thereof called for  redemption on a Redemption  Date during the period
beginning  at the close of business  on a regular  record date and ending at the
opening of business on the first Business Day after the next succeeding interest
payment date, or if such interest payment date is not a Business Day, the second
such Business Day) shall also be accompanied  by payment in funds  acceptable to
the Company of an amount equal to the interest  payable on such interest payment
date on the principal  amount of such Security  then being  converted,  and such
interest  shall  be  payable  to  such  registered  Holder  notwithstanding  the
conversion  of such  Security,  subject  to the  provisions  of  this  Indenture
relating  to the  payment  of  defaulted  interest  by the  Company.  Except  as
otherwise  provided in this Section 4.2, no payment or  adjustment  will be made
for accrued  interest on a converted  Security.  If the Company  defaults in the
payment of interest  payable on such interest  payment  date,  the Company shall
promptly repay such funds to such Holder.
     Nothing in this  Section  shall  affect the right of a Holder in whose name
any Security is  registered at the close of business on a record date to receive
the interest  payable on such Security on the related  interest  payment date in
accordance  with the terms of this  Indenture  and the  Securities.  If a Holder
converts  more than one  Security  at the same  time,  the  number of  Evergreen
Consideration Units issuable upon the conversion shall be based on the aggregate
principal amount of Securities converted.
     Upon  surrender of a Security that is converted in part,  the Company shall
execute,  and the Trustee shall  authenticate  and deliver to the Holder,  a new
Security equal in principal  amount to the  unconverted  portion of the Security
surrendered.
Section 4.3    Fractional Shares
     The Company will not issue  fractional  shares of Pioneer Common Stock upon
conversion of  Securities.  In lieu  thereof,  the Company will pay an amount in
cash based upon the current  market  price  (determined  as set forth in Section
4.6(d)) of Pioneer  Common  Stock on the  Trading Day  immediately  prior to the
Conversion Date.
Section 4.4    Taxes on Conversion
     If a Holder  converts a Security,  the Company  shall pay any  documentary,
stamp or  similar  issue or  transfer  tax due on the issue of shares of Pioneer
Common Stock upon such  conversion.  However,  the Holder shall pay any such tax
                                      A-4

which is due because the Holder requests the shares to be issued in a name other
than the  Holder's  name.  The  Conversion  Agent  may  refuse  to  deliver  the
certificate  representing Pioneer Common Stock being issued in a name other than
the Holder's name until the  Conversion  Agent  receives a sum sufficient to pay
any tax which  will be due  because  the shares are to be issued in a name other
than the  Holder's  name.  Nothing  herein shall  preclude  any tax  withholding
required by law or regulation.
Section 4.5    Pioneer to Provide Stock
     Pioneer shall, prior to issuance of any Securities hereunder, and from time
to time as may be necessary, reserve, out of its authorized but unissued Pioneer
Common Stock,  a sufficient  number of shares of Pioneer  Common Stock to permit
the conversion of all outstanding Securities into shares of Pioneer Common Stock
(in addition to the Cash Component).
     All  shares of  Pioneer  Common  Stock  delivered  upon  conversion  of the
Securities  shall be newly  issued  shares,  shall be duly  authorized,  validly
issued,  fully paid and  nonassessable  and shall be free from preemptive rights
and free of any lien or adverse claim.
     Pioneer  will  endeavor  promptly  to  comply  with all  federal  and state
securities  laws  regulating  the offer and delivery of shares of Pioneer Common
Stock upon  conversion  of  Securities,  if any,  and will list or cause to have
quoted such shares of Pioneer Common Stock on each national  securities exchange
or on the Nasdaq  National  Market ("NNM") or other  over-the-counter  market or
such  other  market on which  Pioneer  Common  Stock is then  listed or  quoted;
provided,  however, that if rules of such automated quotation system or exchange
permit the Company to defer the listing of such  Pioneer  Common Stock until the
first conversion of the Securities into Pioneer Common Stock (in addition to the
Cash  Component) in accordance  with the provisions of this  Indenture,  Pioneer
covenants to list such Pioneer  Common Stock  issuable  upon  conversion  of the
Securities  (in  addition  to  the  Cash   Component)  in  accordance  with  the
requirements of such automated quotation system or exchange at such time.
Section 4.6    Adjustment of Conversion Price
     The  conversion  price as  stated in  paragraph  8 of the  Securities  (the
"Conversion  Price")  shall be  adjusted  from  time to time by the  Company  as
follows:
     (a) In case  Pioneer  shall (i) pay a dividend on Pioneer  Common  Stock in
shares of Pioneer Common Stock, (ii) make a distribution on Pioneer Common Stock
in shares of Pioneer Common Stock,  (iii) subdivide  outstanding  Pioneer Common
Stock into a greater number of shares,  or (iv) combine its outstanding  Pioneer
Common Stock into a smaller  number of shares,  the  Conversion  Price in effect
immediately  prior  thereto shall be adjusted so that the Holder of any Security
thereafter  surrendered for conversion  shall be entitled to receive that number
of shares of Pioneer Common Stock (and the Cash  Component)  which it would have
owned had such Security  been  converted  immediately  prior to the happening of
such event.  An  adjustment  made pursuant to this  subsection  (a) shall become
effective  immediately  after  the  record  date in the  case of a  dividend  or
distribution and shall become effective  immediately after the effective date in
the case of subdivision or combination.
                                      A-5

     (b) In case Pioneer shall issue rights or warrants to all or  substantially
all holders of Pioneer Common Stock  entitling them (for a period  commencing no
earlier than the record date described  below and expiring not more than 60 days
after such record date) to subscribe  for or purchase  shares of Pioneer  Common
Stock (or securities convertible into Pioneer Common Stock) at a price per share
(or having a conversion  price per share) less than the current market price per
share of Pioneer Common Stock (as determined in accordance  with  subsection (d)
of this Section 4.6) on the record date for the  determination  of  stockholders
entitled to receive  such rights or  warrants,  the  Conversion  Price in effect
immediately prior thereto shall be adjusted so that the same shall equal the sum
of (i) the Cash  Component plus (ii) the product  determined by multiplying  (A)
the Conversion Price in effect  immediately  prior to such record date minus the
Cash Component by (B) a fraction,  of which the numerator shall be the number of
shares of Pioneer  Common Stock  outstanding on such record date plus the number
of shares which the  aggregate  offering  price of the total number of shares of
Pioneer  Common  Stock so  offered  (or the  aggregate  conversion  price of the
convertible  securities so offered, which shall be determined by multiplying the
number of shares of  Pioneer  Common  Stock  issuable  upon  conversion  of such
convertible securities by the conversion price per share of Pioneer Common Stock
pursuant  to the terms of such  convertible  securities)  would  purchase at the
current  market  price per share (as defined in  subsection  (d) of this Section
4.6) of Pioneer Common Stock on such record date,  and of which the  denominator
shall be the number of shares of Pioneer Common Stock outstanding on such record
date plus the number of  additional  shares of Pioneer  Common Stock offered (or
into  which  the  convertible  securities  so  offered  are  convertible).  Such
adjustment shall be made  successively  whenever any such rights or warrants are
issued, and shall become effective immediately after such record date. If at the
end of the period during which such rights or warrants are  exercisable  not all
rights or warrants  shall have been  exercised,  the adjusted  Conversion  Price
shall be immediately readjusted to what it would have been based upon the number
of additional  shares of Pioneer Common Stock actually  issued (or the number of
shares  of  Pioneer  Common  Stock  issuable  upon   conversion  of  convertible
securities actually issued).
     (c) In case Pioneer shall distribute to all or substantially all holders of
Pioneer  Common  Stock any shares of Capital  Stock of the  Company  (other than
Pioneer  Common  Stock),  evidences of  indebtedness  or other  non-cash  assets
(including  securities  of any  person  other than  Pioneer  but  excluding  (1)
dividends  or  distributions  paid  exclusively  in  cash  or (2)  dividends  or
distributions  referred to in  subsection  (a) of this  Section  4.6),  or shall
distribute to all or substantially all holders of Pioneer Common Stock rights or
warrants to subscribe  for or purchase any of its  securities  (excluding  those
rights and warrants  referred to in subsection (b) of this Section 4.6), then in
each such case the  Conversion  Price  shall be  adjusted so that the same shall
equal the sum of (i) the Cash  Component  plus (ii) the  product  determined  by
multiplying (A) the current  Conversion  Price minus the Cash Component by (B) a
fraction of which the numerator  shall be the current market price per share (as
defined in  subsection  (d) of this Section 4.6) of Pioneer  Common Stock on the
record date  mentioned  below less the fair market value on such record date (as
determined by the Board of Directors of Pioneer,  whose  determination  shall be
conclusive evidence of such fair market value and which shall be evidenced by an
Officers' Certificate of Pioneer delivered to the Trustee) of the portion of the
Capital Stock, evidences of indebtedness or other non-cash assets so distributed
or of such rights or warrants  applicable  to one share of Pioneer  Common Stock
                                      A-6

(determined  on the  basis of the  number  of shares  of  Pioneer  Common  Stock
outstanding  on the  record  date),  and of which the  denominator  shall be the
current  market  price per share (as defined in  subsection  (d) of this Section
4.6) of Pioneer Common Stock on such record date. Such adjustment  shall be made
successively  whenever any such  distribution is made and shall become effective
immediately after the record date for the determination of shareholders entitled
to receive such distribution.
               (1)  In case Pioneer shall, by dividend or otherwise, at any time
        distribute (a  "Triggering  Distribution") to  all  or substantially all
        holders of  Pioneer  Common  Stock  cash in  an aggregate  amount  that,
        together with the aggregate amount of  (A) any cash and  the fair market
        value  (as  determined  by the  Board  of  Directors of  Pioneer,  whose
        determination shall be  conclusive evidence thereof and  which shall  be
        evidenced by an  Officers' Certificate  delivered to the Trustee) of any
        other  consideration  payable in  respect  of any  tender  offer  by the
        Company  or  a  Subsidiary  of  the  Company for  Pioneer  Common  Stock
        consummated  within the  12 months  preceding the date of payment of the
        Triggering Distribution and  in respect  of which  no  Conversion  Price
        adjustment  pursuant to this Section 4.6 has been made and (B) all other
        cash distributions to all or substantially all holders of Pioneer Common
        Stock made  within the  12 months  preceding  the date of payment of the
        Triggering Distribution  and in  respect  of which  no Conversion  Price
        adjustment pursuant to this Section 4.6 has been made, exceeds an amount
        equal to 10.0%  of the  product of the current market price per share of
        Pioneer Common Stock (as determined in accordance with subsection (d) of
        this  Section 4.6)  on  the  Business  Day  (the  "Determination  Date")
        immediately preceding  the day on  which such Triggering Distribution is
        declared by Pioneer multiplied by the number of shares of Pioneer Common
        Stock  outstanding on the  Determination Date  (excluding shares held in
        the treasury of Pioneer),  the Conversion Price shall be reduced so that
        the same  shall  equal the  sum of  (i) the Cash Component plus (ii) the
        product determined  by multiplying (x) such  Conversion Price  in effect
        immediately  prior to the Determination Date minus the Cash Component by
        (y) a fraction of which  the numerator shall be the current market price
        per share  of  Pioneer  Common  Stock (as determined  in accordance with
        subsection (d) of this Section 4.6)  on the Determination  Date less the
        sum of the aggregate amount of cash  and the aggregate fair market value
        (determined  as  aforesaid in  this Section 4.6(c)(1)) of any such other
        consideration  so distributed,  paid or  payable within  such 12  months
        (including, without limitation,  the Triggering Distribution) applicable
        to one  share of  Pioneer  Common Stock  (determined on the basis of the
        number  of   shares  of   Pioneer  Common   Stock  outstanding   on  the
        Determination Date)  and the  denominator shall  be such current  market
        price per  share of Pioneer  Common Stock  (as determined  in accordance
        with subsection (d) of this Section 4.6) on the Determination Date, such
        reduction  to  become  effective  immediately  prior  to the  opening of
        business on  the day  next following  the date  on which  the Triggering
        Distribution is paid.
               (2) In case any  tender offer  made by  the Company or any of its
        Subsidiaries for Pioneer Common Stock shall expire and such tender offer
        (as amended  upon the  expiration thereof)  shall involve the payment of
        aggregate  consideration  in  an amount  (determined  as the  sum of the
        aggregate amount  of cash  consideration and the  aggregate fair  market
        value  (as  determined  by  the  Board of  Directors of  Pioneer,  whose
                                      A-7

        determination shall  be conclusive  evidence thereof  and which shall be
        evidenced by an Officers' Certificate delivered to the  Trustee thereof)
        of any other consideration) that, together with the  aggregate amount of
        (A) any cash and the  fair market value  (as determined  by the Board of
        Directors of Pioneer,  whose determination  shall be conclusive evidence
        thereof and which  shall be  evidenced  by an  Officers'  Certificate of
        Pioneer  delivered to the Trustee) of any other consideration payable in
        respect of  any other  tender offers  by Pioneer  or any  Subsidiary  of
        Pioneer for  Pioneer Common  Stock  consummated  within  the  12  months
        preceding the  date of  the Expiration  Date (as  defined  below) and in
        respect of which no Conversion Price adjustment pursuant to this Section
        4.6 has been made and (B) all cash distributions to all or substantially
        all holders of Pioneer Common Stock made within the  12 months preceding
        the  Expiration  Date  and  in  respect of  which  no  Conversion  Price
        adjustment pursuant to this Section 4.6 has been made, exceeds an amount
        equal to 10.0% of the product of the  current market  price per share of
        Pioneer Common Stock (as determined in accordance with subsection (d) of
        this Section 4.6)  as of the last date  (the "Expiration Date")  tenders
        could  have  been made  pursuant to  such  tender  offer (as  it may  be
        amended) (the last  time at which  such tenders could  have been made on
        the  Expiration  Date is  hereinafter  sometimes called  the "Expiration
        Time")  multiplied by  the  number  of  shares  of Pioneer  Common Stock
        outstanding  (including tendered shares but excluding any shares held in
        the treasury of Pioneer) at the Expiration Time, then, immediately prior
        to the  opening  of business on the  day after  the Expiration Date, the
        Conversion Price shall be reduced so  that the same  shall equal the sum
        of  (i)   the  Cash  Component  plus  (ii)  the  product  determined  by
        multiplying  (I) the  Conversion Price  in effect  immediately  prior to
        close of business on the  Expiration  Date minus  the Cash  Component by
        (II) a fraction  of which the  numerator shall  be  the  product of  the
        number of shares of Pioneer Common Stock outstanding (including tendered
        shares but excluding any shares held in the treasury of Pioneer)  at the
        Expiration  Time  multiplied by the  current market price  per share  of
        Pioneer Common Stock (as determined in accordance with subsection (d) of
        this Section 4.6) on the Trading Day next succeeding the Expiration Date
        and the denominator shall be the sum of (x) the  aggregate consideration
        (determined  as  aforesaid)   payable  to  stockholders   based  on  the
        acceptance  (up to  any maximum  specified in  the terms  of the  tender
        offer)  of all  shares  validly  tendered  and not  withdrawn as  of the
        Expiration  Time (the shares deemed so accepted, up to any such maximum,
        being referred to  as the "Purchased Shares") and (y) the product of the
        number of shares of Pioneer Common Stock outstanding (less any Purchased
        Shares and excluding  any shares held in the treasury of Pionner) at the
        Expiration Time and the current market price per share of Pioneer Common
        Stock (as determined in  accordance with  subsection (d) of this Section
        4.6) on  the  Trading  Day  next  succeeding the  Expiration Date,  such
        reduction  to become  effective immediately  prior  to  the  opening  of
        business on the day following the  Expiration  Date.  In the event  that
        Pioneer is  obligated to  purchase  shares  pursuant to  any such tender
        offer,  but  Pioneer is  permanently  prevented by  applicable  law from
        effecting any  or  all such  purchases or any  or all such purchases are
        rescinded,  the  Conversion  Price  shall  again be  adjusted to  be the
        Conversion Price which would have been in  effect based upon the  number
        of shares  actually  purchased.  If  the  application  of  this  Section
        4.6(c)(2) to  any tender  offer  would  result  in  an  increase  in the
        Conversion Price,  no adjustment shall be  made  for  such  tender offer
        under this Section 4.6(c)(2).
                                      A-8

               (3) For purposes of this Section 4.6(c),  the term "tender offer"
        shall mean  and include  both tender  offers and  exchange  offers,  all
        references to  "purchases" of shares  in tender offers  (and all similar
        references) shall mean and include both the purchase of shares in tender
        offers and the  acquisition of  shares pursuant to  exchange offers, and
        all references to "tendered shares"  (and all similar  references) shall
        mean and  include  shares tendered  in both  tender offers  and exchange
        offers.
     (d) For the purpose of any computation  under  subsections (b), (c) and (d)
of this Section 4.6, the current  market price per share of Pioneer Common Stock
on any date shall be deemed to be the  average of the daily  closing  prices for
the 30  consecutive  Trading  Days  commencing  45 Trading  Days  before (i) the
Determination  Date or the Expiration  Date, as the case may be, with respect to
distributions  or tender offers under subsection (c) of this Section 4.6 or (ii)
the  record  date with  respect  to  distributions,  issuances  or other  events
requiring such computation  under subsection (b) or (c) of this Section 4.6. The
closing price for each day shall be the last reported sales price or, in case no
such reported sale takes place on such date, the average of the reported closing
bid and asked  prices in either case on the NNM or, if Pioneer  Common  Stock is
not  listed  or  admitted  to  trading  on the NNM,  on the  principal  national
securities  exchange  on which  Pioneer  Common  Stock is listed or  admitted to
trading  or, if not listed or  admitted  to  trading on the NNM or any  national
securities  exchange,  the last reported  sales price of Pioneer Common Stock as
quoted on NASDAQ or, in case no reported  sales takes place,  the average of the
closing bid and asked prices as quoted on NASDAQ or any comparable system or, if
Pioneer  Common  Stock is not  quoted on NASDAQ or any  comparable  system,  the
closing sales price or, in case no reported sale takes place, the average of the
closing bid and asked  prices,  as  furnished by any two members of the National
Association of Securities  Dealers,  Inc.  selected from time to time by Pioneer
for that purpose. If no such prices are available,  the current market price per
share shall be the fair value of a share of Pioneer  Common Stock as  determined
by the Board of Directors  of Pioneer  (which shall be evidenced by an Officers'
Certificate of Pioneer delivered to the Trustee).
     (e) In any case in which this Section 4.6 shall  require that an adjustment
be made following a record date or a Determination  Date or Expiration  Date, as
the case may be, established for purposes of this Section 4.6, Pioneer may elect
to defer (but only until five Business Days  following the filing by the Company
with the Trustee of the  certificate  described  in Section  4.9) issuing to the
Holder of any Security converted after such record date or Determination Date or
Expiration  Date the shares of Pioneer  Common Stock and other  Capital Stock of
Pioneer  issuable  upon such  conversion  over and above the  shares of  Pioneer
Common Stock and other  Capital Stock of Pioneer  issuable upon such  conversion
only on the basis of the Conversion  Price prior to adjustment;  and, in lieu of
the shares the  issuance of which is so deferred,  Pioneer  shall issue or cause
its transfer agents to issue due bills or other appropriate evidence prepared by
Pioneer of the right to receive such shares.  If any  distribution in respect of
which an  adjustment  to the  Conversion  Price is required to be made as of the
record date or Determination  Date or Expiration Date therefor is not thereafter
made or paid by Pioneer for any reason, the Conversion Price shall be readjusted
to the  Conversion  Price  which would then be in effect if such record date had
not been fixed or such effective date or  Determination  Date or Expiration Date
had not occurred.
                                      A-9

Section 4.7    No Adjustment
     No  adjustment  in the  Conversion  Price  shall  be  required  unless  the
adjustment  would  require  an  increase  or  decrease  of at  least  1% in  the
Conversion Price as last adjusted; provided, however, that any adjustments which
by reason of this  Section  4.7 are not  required  to be made  shall be  carried
forward and taken into account in any subsequent  adjustment.  All  calculations
under  this  Article  IV shall  be made to the  nearest  cent or to the  nearest
one-hundredth of a share, as the case may be.
     No adjustment  need be made for issuances of Pioneer  Common Stock pursuant
to a Pioneer plan for  reinvestment  of dividends or interest or for a change in
the par value or a change to no par value of Pioneer Common Stock.
     To the extent  that the  Securities  become  convertible  into the right to
receive  cash, no adjustment  need be made  thereafter as to the cash.  Interest
will not accrue on the cash.
Section 4.8    Adjustment for Tax Purposes
     The Company  shall be entitled to make such  reductions  in the  Conversion
Price,  in addition to those  required by Section  4.6, as it in its  discretion
shall determine to be advisable in order that any stock dividends,  subdivisions
of  shares,   distributions  of  rights  to  purchase  stock  or  securities  or
distributions of securities convertible into or exchangeable for stock hereafter
made by Pioneer to its stockholders shall not be taxable.
Section 4.9    Notice of Adjustment
     Whenever the  Conversion  Price or  conversion  privilege is adjusted,  the
Company shall  promptly mail to  Securityholders  a notice of the adjustment and
file  with the  Trustee  an  Officers'  Certificate  briefly  stating  the facts
requiring  the  adjustment  and the manner of computing it. Unless and until the
Trustee  shall receive an Officers'  Certificate  setting forth an adjustment of
the Conversion Price, the Trustee may assume without inquiry that the Conversion
Price has not been adjusted and that the last  Conversion  Price of which it has
knowledge remains in effect.
Section 4.10    Notice of Certain Transactions
        In the event that:
             (1)   Pioneer takes any action which would require an adjustment in
        the Conversion Price;
             (2)   Pioneer  consolidates or  merges with,  or  transfers  all or
        substantially all of its property and assets to, another corporation and
        shareholders of Pioneer must approve the transaction; or
             (3)   there  is a  dissolution or  liquidation  of  the Company  or
        Pioneer,
                                      A-10

the Company shall mail to Holders and file with the Trustee a notice stating the
proposed  record or effective  date,  as the case may be. The Company shall mail
the notice at least ten days  before  such date.  Failure to mail such notice or
any defect therein shall not affect the validity of any transaction  referred to
in clause (1), (2) or (3) of this Section 4.10.
Section 4.11    Effect of Reclassification, Consolidation, Merger or Sale on
                Conversion Privilege
     If any of the following shall occur,  namely: (a) any  reclassification  or
change of  shares of  Pioneer  Common  Stock  issuable  upon  conversion  of the
Securities (other than a change in par value, or from par value to no par value,
or  from  no  par  value  to par  value,  or as a  result  of a  subdivision  or
combination,  or any other change for which an adjustment is provided in Section
4.6); (b) any consolidation or merger or combination to which Pioneer is a party
other than a merger in which  Pioneer is the  continuing  corporation  and which
does not result in any  reclassification of, or change (other than in par value,
or from par value to no par value,  or from no par value to par  value,  or as a
result of a subdivision or combination) in, outstanding shares of Pioneer Common
Stock;  or (c) any sale or  conveyance  as an  entirety or  substantially  as an
entirety of the property and assets of Pioneer,  directly or indirectly,  to any
person, then Pioneer, or such successor,  purchasing or transferee  corporation,
as the case may be, shall,  as a condition  precedent to such  reclassification,
change,  combination,  consolidation,  merger,  sale or conveyance,  execute and
deliver to the Trustee a  supplemental  indenture  providing  that the Holder of
each  Security  then  outstanding  shall have the right to convert such Security
into the kind and amount of shares of stock and other  securities  and  property
(including cash)  receivable upon such  reclassification,  change,  combination,
consolidation, merger, sale or conveyance by a holder of the number of shares of
Pioneer Common Stock  deliverable  upon conversion of such Security (in addition
to the  Cash  Component)  immediately  prior to such  reclassification,  change,
combination,  consolidation,  merger,  sale  or  conveyance.  Such  supplemental
indenture shall provide for  adjustments of the Conversion  Price which shall be
as nearly  equivalent as may be practicable to the adjustments of the Conversion
Price   provided  for  in  this  Article  IV.  If,  in  the  case  of  any  such
consolidation,  merger,  combination,  sale or  conveyance,  the  stock or other
securities and property  (including  cash)  receivable  thereupon by a holder of
Pioneer Common Stock include shares of stock or other securities and property of
a person other than the successor,  purchasing or transferee corporation, as the
case may be, in such  consolidation,  merger,  combination,  sale or conveyance,
then such supplemental indenture shall also be executed by such other person and
shall contain such additional provisions to protect the interests of the Holders
of the Securities as the Board of Directors shall reasonably  consider necessary
by reason of the foregoing.  The provisions of this Section 4.11 shall similarly
apply to successive reclassifications,  changes,  combinations,  consolidations,
mergers, sales or conveyances.
     In the event the Company shall execute a supplemental indenture pursuant to
this  Section  4.11,  the Company  shall  promptly  file with the Trustee (x) an
Officers'  Certificate briefly stating the reasons therefor,  the kind or amount
of shares of stock or other  securities or property  (including cash) receivable
by Holders of the Securities upon the conversion of their  Securities  after any
such  reclassification,  change,  combination,  consolidation,  merger,  sale or
conveyance,  any  adjustment  to be made  with  respect  thereto  and  that  all
conditions  precedent have been complied with and (y) an Opinion of Counsel that
all conditions precedent have been complied with, and shall promptly mail notice
thereof to all Holders.
                                      A-11

Section 4.12    Trustee's Disclaimer
     The Trustee shall have no duty to determine  when an adjustment  under this
Article IV should be made, how it should be made or what such adjustment  should
be, but may accept as conclusive evidence of that fact or the correctness of any
such  adjustment,   and  shall  be  protected  in  relying  upon,  an  Officers'
Certificate  including the Officers'  Certificate with respect thereto which the
Company is  obligated  to file with the  Trustee  pursuant to Section  4.9.  The
Trustee makes no representation as to the validity or value of any securities or
assets  issued upon  conversion  of  Securities,  and the  Trustee  shall not be
responsible  for the  Company's  failure to comply with any  provisions  of this
Article IV.
     The  Trustee  shall  not be  under  any  responsibility  to  determine  the
correctness of any provisions  contained in any supplemental  indenture executed
pursuant  to  Section  4.11,  but  may  accept  as  conclusive  evidence  of the
correctness thereof, and shall be fully protected in relying upon, the Officers'
Certificate with respect thereto which the Company is obligated to file with the
Trustee pursuant to Section 4.11.
Section 4.13    Voluntary Reduction
     The Company from time to time may reduce the Conversion Price by any amount
for any period of time if the period is at least 20 days and if the reduction is
irrevocable  during the period if the Board of  Directors  determines  that such
reduction would be in the best interest of the Company and the Company  provides
15 days  prior  notice  of any  reduction  in the  Conversion  Price;  provided,
however, that in no event may the Company reduce the Conversion Price to be less
than the par value of a share of Pioneer Common Stock.
                                      A-12

                                    ANNEX B
        8. Conversion
Subject  to  compliance  with the  provisions  of the  Indenture,  a Holder of a
Security  may  convert the  principal  amount of such  Security  (or any portion
thereof  equal to $1,000 or any integral  multiple of $1,000 in excess  thereof)
into Evergreen Consideration Units at the Conversion Price in effect at the time
of conversion under certain circumstances described in the Indenture;  provided,
however,  that if the Security is called for redemption or subject to repurchase
upon a specific  date pursuant to Article V of the Indenture or upon a Change in
Control,  the  conversion  right will  terminate at the close of business on the
Business Day immediately  preceding the redemption date or the Change in Control
Repurchase  Date,  as the case may be, for such Security or such earlier date as
the Holder presents such Security for redemption or purchase (unless the Company
shall default in making the redemption  payment,  Optional  Repurchase  Price or
Change in Control  Repurchase Price, as the case may be, when due, in which case
the conversion  right shall  terminate at the close of business on the date such
default is cured and such Security is redeemed or purchased).
     The  Company  will  notify  Holders  of any event  triggering  the right to
convert the Security as specified above in accordance with the Indenture.
     A  Security  in  respect  of  which a  Holder  has  delivered  an  Optional
Repurchase Notice or a Change in Control Repurchase Notice exercising the option
of such  Holder to  require  the  Company to  repurchase  such  Security  may be
converted  only if such notice of exercise is withdrawn in  accordance  with the
terms of the Indenture.
     The Conversion Price is $25.00 per Evergreen Consideration Unit, subject to
adjustment under certain  circumstances.  The number of Evergreen  Consideration
Units  issuable  upon  conversion  of a Security is  determined  by dividing the
principal amount of the Security or portion thereof  converted by the Conversion
Price in effect on the Conversion Date. No fractional shares will be issued upon
conversion;  in lieu  thereof,  an amount  will be paid in cash  based  upon the
closing  price (as  defined in the  Indenture)  of Pioneer  Common  Stock on the
Trading Day immediately prior to the Conversion Date.
To  convert  a  Security,  a Holder  must (a)  complete  and  manually  sign the
conversion notice set forth below and deliver such notice to a Conversion Agent,
(b)  surrender  the  Security to a  Conversion  Agent,  (c) furnish  appropriate
endorsements  and transfer  documents if required by a Registrar or a Conversion
Agent,  and (d) pay any  transfer or similar  tax, if  required.  Securities  so
surrendered  for  conversion  (in whole or in part)  during the period  from the
close of business  on any Regular  Record Date to the opening of business on the
next succeeding Interest Payment Date (excluding  Securities or portions thereof
called for redemption or subject to repurchase  upon a specific date pursuant to
Article V of the  Indenture  or upon a Change in Control on a  Redemption  Date,
Optional  Repurchase Date or Change in Control  Repurchase Date, as the case may
be,  during the period  beginning  at the close of business on a Regular  Record
Date and ending at the opening of business on the first  Business  Day after the
next succeeding Interest Payment Date, or if such Interest Payment Date is not a
Business Day, the second such Business Day) shall also be accompanied by payment
                                      B-1

in funds acceptable to the Company of an amount equal to the interest payable on
such Interest  Payment Date on the principal  amount of such Security then being
converted,  and  such  interest  shall  be  payable  to such  registered  Holder
notwithstanding  the conversion of such  Security,  subject to the provisions of
this Indenture relating to the payment of defaulted interest by the Company.  If
the Company defaults in the payment of interest (including  Contingent Interest)
payable on such Interest  Payment Date,  the Company shall  promptly  repay such
funds to such  Holder.  A Holder may  convert a portion  of a Security  equal to
$1,000 or any integral multiple thereof.
                                      B-2

                                     ANNEX C
                                CONVERSION NOTICE
     To convert this Security into Evergreen Consideration Units, check the box:
| |
     To convert only part of this  Security,  state the  principal  amount to be
converted (must be $1,000 or a multiple of $1,000):
$
- ------------.
     If you want the stock  certificate  made out in another person's name, fill
in the form below:
- --------------------------------------------------------------------------------
                  (Insert assignee's soc. sec. or tax I.D. no.)
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
              (Print or type assignee's name, address and zip code)
                                      Your Signature:
Date:
       ---------------------------    ------------------------------------------
                                      (Sign exactly as your name appears on the
                                      other aide of this Security)
*Signature guaranteed by:
By:
      ----------------------------
- -------------
*    The Signature must be guaranteed by an institution which is a member of one
     of  the  following  recognized  signature  guarantly  programs  :  (i)  the
     Securities  Transfer Agent  Medallion  Program  (STAMP);  (ii) the New York
     Stock Exchange  Medallion Program (MSP); (iii) the Stock Exchange Medallion
     Program  (SEMP);  or (iv) such other  guaranty  program  acceptable  to the
     Trustee.
                                      C-1

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