Document:

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                                                                     Exhibit 4.1

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                                WARRANT AGREEMENT

                                 BY AND BETWEEN

                               KOMAG, INCORPORATED

                                       AND

                               FLEET NATIONAL BANK
                             F/K/A BANKBOSTON, N.A.

                                BANK OF MONTREAL

                            BEAR, STEARNS & CO. INC.

                           COMERICA BANK - CALIFORNIA

                            OLYMPUS SECURITIES, LTD.

                              NELSON PARTNERS LTD.

                             THE BANK OF NOVA SCOTIA

                         UNION BANK OF CALIFORNIA, N.A.

                            LOEB PARTNERS CORPORATION

                        THE DAI-ICHI KANGYO BANK, LIMITED

           THE INDUSTRIAL BANK OF JAPAN, LIMITED, SAN FRANCISCO AGENCY

                  THE MITSUBISHI TRUST AND BANKING CORPORATION

                              SANWA BANK CALIFORNIA

                       THE FIRST NATIONAL BANK OF CHICAGO

                             THE FUJI BANK, LIMITED

                           THE SUMITOMO BANK, LIMITED

                            DATED AS OF MAY 25, 2000

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                               TABLE OF CONTENTS(1)

<TABLE>
<CAPTION>
                                                                                          Page
<S>                                                                                       <C>
SECTION 1.  Warrant Certificates; Issuance of Warrants.......................................1

SECTION 2.  Execution of Warrant Certificates................................................2

SECTION 3.  Registration.....................................................................2

SECTION 4.  Registration of Transfers and Exchanges..........................................2

SECTION 5.  Warrants; Exercise of Warrants...................................................3

SECTION 6.  Payment of Taxes.................................................................5

SECTION 7.  Mutilated or Missing Warrant Certificates........................................5

SECTION 8.  Reservation of Warrant Shares; Rights............................................5

SECTION 9.  Obtaining Stock Exchange Listings................................................6

SECTION 10.  Adjustment of Exercise Price and Number of Warrant Shares Issuable..............6
               (a) Adjustment for Change in Capital Stock....................................6
               (b) Adjustment for Rights Issue...............................................7
               (c) Adjustment for Other Distributions........................................8
               (d) Adjustment for Common Stock Issue.........................................8
               (e) Adjustment for Convertible Securities Issue...............................9
               (f) Current Market Price.....................................................10
                      (1) Current Market Price..............................................10
                      (2) Fair Market Value.................................................11
                      (3) Independent Expert................................................11
               (g) Consideration Received...................................................11
               (h) When De Minimis Adjustment May Be Deferred...............................12
               (i) When No Adjustment Required..............................................12
               (j) Notice of Adjustment.....................................................12
               (k) Voluntary Reduction......................................................12
               (l) Reorganization of Company................................................13
               (m) When Issuance or Payment May Be Deferred.................................14
               (n) Adjustment in Number of Shares...........................................14
               (o) Form of Warrants.........................................................14

SECTION 11.  Fractional Interests...........................................................14
</TABLE>

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(1)  This Table of Contents does not constitute a part of this Agreement or have
     any bearing upon the interpretation of any of its terms or provisions.

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<TABLE>
<S>                                                                                       <C>
SECTION 12.  Representations and Warranties to the Company..................................15
               (a) Corporate Organization...................................................15
               (b) Authorization............................................................15
               (c) Governmental Consents....................................................15
               (d) Validity.................................................................16
               (e) Not an Investment Company................................................16
               (f) Reports..................................................................16
               (g) Authorized Shares........................................................16
               (h) Status of the Warrants and the Warrant Shares............................17

SECTION 13.  Purchase for Investment; Authority; Binding Agreement..........................17

SECTION 14.  Notices to Warrant Holders.....................................................17

SECTION 15.  Notices to Company and Warrant Holder..........................................19

SECTION 16.  Supplements and Amendments.....................................................19

SECTION 17.  Successors.....................................................................19

SECTION 18.  Governing Law..................................................................20

SECTION 19.  Benefits of This Agreement.....................................................20

SECTION 20.  Counterparts...................................................................20

SCHEDULE 1...................................................................................1

EXHIBIT A....................................................................................1

EXHIBIt B....................................................................................1
</TABLE>

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        THIS WARRANT AGREEMENT (the "Agreement") is dated as of May 25, 2000,
and entered into by and among Komag, Incorporated, a Delaware corporation (the
"Company"), and Fleet National Bank f/k/a BankBoston, N.A., Bank of Montreal,
Bear, Stearns & Co. Inc., Comerica Bank - California, Olympus Securities, Ltd.,
Nelson Partners Ltd., The Bank of Nova Scotia, Union Bank of California, N.A.,
Loeb Partners Corporation, The Dai-Ichi Kangyo Bank, Limited, The Industrial
Bank of Japan, Limited, San Francisco Agency, The Mitsubishi Trust and Banking
Corporation, Sanwa Bank California, The First National Bank of Chicago, The Fuji
Bank, Limited, and The Sumitomo Bank, Limited (collectively, "Banks").

        WHEREAS, the Banks have made loans and otherwise extended credit in the
aggregate outstanding principal amount of $260,000,000 to the Company pursuant
to certain existing credit facilities;

        WHEREAS, pursuant to a Loan Restructure Agreement dated as of the date
hereof (the "Loan Restructure Agreement"), Banks propose to restructure such
existing credit facilities (as so restructured, the "Credit Facilities"); and

        WHEREAS, to induce Banks to enter into the Loan Restructure Agreement
and to restructure such existing credit facilities, pursuant thereto the Company
proposes to issue to Banks, or their respective designees, Common Stock Purchase
Warrants as hereinafter described (the "Warrants"), to collectively purchase
common stock of the Company, $0.01 par value (the "Common Stock") equal to, in
the aggregate, 3.5% of the issued and outstanding Common Stock (the Common Stock
issuable on exercise of the Warrants being referred to herein as the "Warrant
Shares"), pursuant to this Agreement.

        NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the parties hereto agree as follows:

        SECTION 1. Warrant Certificates; Issuance of Warrants. The certificates
evidencing the Warrants (the "Warrant Certificates") to be delivered to the
Banks or their respective designees permitted as assignees under the Loan
Restructure Agreement, in the respective amounts set forth in Schedule 1 hereto,
pursuant to this Agreement shall be in registered form only and shall be
substantially in the respective forms set forth in Exhibits A and B attached
hereto.

        The Warrants shall be issuable as follows:

               (a) Series A Warrants: The Series A Warrants shall be exercisable
into a number of shares of Common Stock equal to, in the aggregate, 2.5% of the
issued and outstanding Common Stock as of the date of issuance of the Warrants.

               (b) Series B Warrants: The Series B Warrants shall be exercisable
into a number of shares of Common Stock equal to, in the aggregate, 1.0% of the
issued and outstanding Common Stock as of the date of issuance of the Warrants.

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        SECTION 2. Execution of Warrant Certificates. Warrant Certificates shall
be signed on behalf of the Company by its Chairman of the Board of Directors of
the Company (the "Board") or its President or a Vice President and by its
Secretary or an Assistant Secretary under its corporate seal. Each such
signature upon the Warrant Certificates may be in the form of a facsimile
signature of the present or any future Chairman of the Board, President, Vice
President, Secretary or Assistant Secretary and may be imprinted or otherwise
reproduced on the Warrant Certificates and for that purpose the Company may
adopt and use the facsimile signature of any person who shall have been Chairman
of the Board, President, Vice President, Secretary or Assistant Secretary,
notwithstanding the fact that, at the time the Warrant Certificates shall be
delivered or disposed of, he shall have ceased to hold such office. The seal of
the Company may be in the form of a facsimile thereof and may be impressed,
affixed, imprinted or otherwise reproduced on the Warrant Certificates.

        In case any officer of the Company who shall have signed any of the
Warrant Certificates shall cease to be such officer before the Warrant
Certificates so signed shall have been disposed of by the Company, such Warrant
Certificates nevertheless may be delivered or disposed of as though such person
had not ceased to be such officer of the Company; and any Warrant Certificate
may be signed on behalf of the Company by any person who, at the actual date of
the execution of such Warrant Certificate, shall be a proper officer of the
Company to sign such Warrant Certificate, although at the date of the execution
of this Warrant Agreement any such person was not such officer.

        SECTION 3. Registration. The Company shall number and register the
Warrant Certificates in a register as they are issued.

        SECTION 4. Registration of Transfers and Exchanges. The Company shall
from time to time register the transfer of any outstanding Warrant Certificates
in a Warrant register to be maintained by the Company upon surrender of such
Warrant Certificates accompanied by a written instrument or instruments of
transfer in form satisfactory to the Company, duly executed by the registered
holder or holders thereof or by the duly appointed legal representative thereof
or by a duly authorized attorney. Upon any such registration of transfer, a new
Warrant Certificate shall be issued to the transferee(s) and the surrendered
Warrant Certificate shall be canceled and disposed of by the Company.

        The Warrant holders agree that each certificate representing Warrant
Shares will bear the following legend:

        THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
        UNDER THE SECURITIES ACT OF 1933 OR THE SECURITIES LAWS OF ANY STATE AND
        MAY NOT BE SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE
        REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
        LAWS OR AN APPLICABLE EXEMPTION TO THE REGISTRATION REQUIREMENTS OF SUCH
        ACT OR SUCH LAWS. SUCH

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        SALE OR OTHER DISPOSITION MUST ALSO BE IN COMPLIANCE WITH THE
        RESTRICTIONS ON TRANSFER SET FORTH IN THE WARRANT AGREEMENT DATED AS OF
        MAY 25 2000, AS MODIFIED OR SUPPLEMENTED FROM TIME TO TIME, A COPY OF
        WHICH MAY BE OBTAINED FROM KOMAG, INCORPORATED AT ITS PRINCIPAL
        EXECUTIVE OFFICE.

        Warrant Certificates may be exchanged at the option of the holder(s)
thereof, when surrendered to the Company at its office for another Warrant
Certificate or other Warrant Certificates of like tenor and representing in the
aggregate a like number of Warrants, and such holder(s) shall pay all reasonable
out-of-pocket expenses actually incurred by Company in connection with such
exchange. Warrant Certificates surrendered for exchange shall be canceled and
disposed of by the Company.

        SECTION 5. Warrants; Exercise of Warrants. Subject to the terms of this
Agreement, each holder of Series A Warrants shall have the right, which may be
exercised commencing as of the date hereof until 5:00 p.m., Los Angeles time on
May 25, 2010, to receive from the Company the number of fully paid and
nonassessable Warrant Shares which the holder may at the time be entitled to
receive on exercise of such Warrants and payment to the Company of the Exercise
Price (as defined below) then in effect for such Warrant Shares. Each Series A
Warrant not exercised prior to 5:00 p.m., Los Angeles time, on May 25, 2010
shall become void and all rights thereunder and all rights in respect thereof
under this Agreement shall cease as of such time. The Company shall notify each
holder of Series A Warrants in writing 90 days prior to the expiration of all
unexercised Series A Warrants, of the upcoming expiration of all such
unexercised Warrants.

        Subject to the terms of this Agreement, each holder of Series B Warrants
shall have the right, which may be exercised commencing at the opening of
business on May 25, 2001 and until 5:00 p.m., Los Angeles time on May 25, 2011,
to receive from the Company the number of fully paid and nonassessable Warrant
Shares which the holder may at the time be entitled to receive on exercise of
such Warrants and payment to the Company of the Exercise Price then in effect
for such Warrant Shares. Each Series B Warrant not exercised prior to 5:00 p.m.,
Los Angeles time on May 25, 2011, shall become void and all rights thereunder
and all rights in respect thereof under this Agreement shall cease as of such
time. The Company shall notify each holder of Series B Warrants in writing 90
days prior to the expiration of all unexercised Series B Warrants, of the
upcoming expiration of all such unexercised Warrants. Notwithstanding anything
to the contrary in this Agreement, the Series B Warrants shall become void and
all rights thereunder and all rights in respect thereof under this Agreement
shall cease if the unpaid loan balances on the notes issued pursuant to the
Credit Facilities, in the aggregate, does not exceed $160,000,000.

        A Warrant may be exercised upon surrender to the Company at its office
designated for such purpose (the address of which is set forth in Section 14
hereof) of the certificate or certificates evidencing the Warrants to be
exercised with the form of election to purchase duly filled in and signed, which
signature shall be guaranteed by a bank or trust company having an

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office or correspondent in the United States or a broker or dealer which is a
member of a registered securities exchange or the National Association of
Securities Dealers, Inc., and upon payment to the Company of the exercise price
(the "Exercise Price") which is set forth in the applicable form of Warrant
Certificate attached here as Exhibit A or B, respectively, subject to adjustment
pursuant to Section 10, for the number of Warrant Shares in respect of which
such Warrants are then exercised. For Warrants exercised within two years of
their date of issuance, payment of the aggregate Exercise Price shall be made,
in lieu of any cash payment, by surrendering such Warrants in exchange for a
number of Warrant Shares equal to the product of (x) the number of Warrant
Shares issuable upon exercise of the Warrants being surrendered multiplied by
(y) a fraction, the numerator of which is the Current Market Price (determined
in accordance with Section 10(f) hereof) of the Warrant Shares less the Exercise
Price, and the denominator of which is such Current Market Price (the surrender
of Warrants in lieu of any cash payment is hereinafter referred to as a
"Cashless Exercise"). For Warrants exercised after two years from their date of
issuance, payment of the aggregate Exercise Price shall be made (i) in cash or
by immediately available funds payable to the order of the Company or (ii) by a
Cashless Exercise.

        Upon such surrender of Warrants and payment of the Exercise Price, the
Company shall, at its sole cost and expense, issue and cause to be delivered
with all reasonable dispatch to or upon the written order of the holder and in
such name or names as the Warrant holder may designate, a certificate or
certificates for the number of full Warrant Shares issuable upon the exercise of
such Warrants together with cash as provided in Section 11; provided, however,
that if any reclassifications, consolidation, merger or lease or sale of assets
is proposed to be effected by the Company as described in subsection (1) of
Section 10 hereof, or a tender offer or an exchange offer for shares of Common
Stock of the Company shall be made, upon such surrender of Warrants and payment
of the Exercise Price as aforesaid, the Company shall, as soon as possible, but
in any event not later than five business days thereafter, issue and cause to be
delivered the full number of Warrant Shares issuable upon the exercise of such
Warrants in the manner described in this sentence together with cash as provided
in Section 11. Such certificate or certificates shall be deemed to have been
issued and any person so designated to be named therein shall be deemed to have
become a holder of record of such Warrant Shares as of the date of the surrender
of such Warrants and payment of the Exercise Price.

        The Warrants shall be exercisable, at the election of the holders
thereof, either in full or from time to time in part; provided, however, that no
partial exercise shall be for an amount less than 2,000 Warrant Shares or, if
less, the total number of Warrant Shares purchasable by the exercising holder.
In the event that a certificate evidencing Warrants is exercised in respect of
fewer than all of the Warrant Shares issuable on such exercise at any time prior
to the date of expiration of the Warrants, a new certificate evidencing the
remaining Warrant or Warrants will be issued and delivered pursuant to the
provisions of this Section and Section 2 hereof.

        All Warrant Certificates surrendered upon exercise of Warrants shall be
canceled and disposed of by the Company. The Company shall keep copies of this
Agreement and any notices given or received hereunder available for inspection
by the holders during normal business hours

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at its office or such other place as the Company may from time to time designate
by written notice to the holders.

        SECTION 6. Payment of Taxes. The Company will pay all stamp,
documentary, transfer or similar taxes attributable to the initial issuance of
the Warrants and the Warrant Shares upon the exercise of Warrants.

        SECTION 7. Mutilated or Missing Warrant Certificates. In case any of the
Warrant Certificates shall be mutilated lost, stolen or destroyed, the Company
shall issue, in exchange and substitution for and upon cancellation of the
mutilated Warrant Certificate, or in lieu of and substitution for the Warrant
Certificate lost, stolen or destroyed, a new Warrant Certificate of like tenor
and representing an equivalent number of Warrants, but only upon receipt of
evidence reasonably satisfactory to the Company of such loss, theft or
destruction of such Warrant Certificate and indemnity also reasonably
satisfactory to it. Applicants for such substitute Warrant Certificates shall
also comply with such other reasonable regulations as the Company may prescribe
and shall pay all reasonable out of pocket expenses actually incurred by Company
in connection with any such exchange and substitution described in this Section
7.

        SECTION 8. Reservation of Warrant Shares; Rights. The Company will at
all times reserve and keep available free from preemptive rights, out of the
aggregate of its authorized but unissued Common Stock or its authorized and
issued Common Stock held in its treasury, for the purpose of enabling it to
satisfy any obligation to issue Warrant Shares upon exercise of Warrants, the
maximum number of shares of Common Stock which may then be deliverable upon the
exercise of all outstanding Warrants.

        The Company shall issue, together with each Warrant Share issued upon
exercise of a Warrant, any rights issued to holders of Common Stock in addition
thereto or in replacement therefor, whether or not such rights shall be
exercisable at such time, but only if such rights are issued and outstanding and
held by other holders of Common Stock at such time and have not expired.

        The Company or, if appointed, the transfer agent for the Common Stock
(the "Transfer Agent") and every subsequent transfer agent for any shares of the
Company's capital stock issuable upon the exercise of any of the rights of
purchase aforesaid will be irrevocably authorized and directed at all times to
reserve such number of authorized shares as shall be required for such purpose.
The Company will keep a copy of this Agreement on file with the Transfer Agent
and with every subsequent transfer agent for any shares of the Company's capital
stock issuable upon the exercise of the rights of purchase represented by the
Warrants. The Company will furnish such Transfer Agent a copy of all notices of
adjustments and certificates related thereto, transmitted to each holder
pursuant to Section 14 hereof.

        Before taking any action which would cause an adjustment pursuant to
Section 10 hereof to reduce the Exercise Price below the then par value (if any)
of the Warrant Shares, the Company will take any corporate action which may, in
the opinion of its counsel, be necessary in

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order that the Company may validly and legally issue fully paid and
nonassessable Warrant Shares at the Exercise Price as so adjusted.

        SECTION 9. Obtaining Stock Exchange Listings. The Company will from time
to time take all action which may be necessary so that the Warrant Shares,
immediately upon their issuance upon the exercise of Warrants, will be listed or
quoted on the principal securities exchanges and markets within the United
States of America, if any, on which other shares of Common Stock are then
listed.

        SECTION 10. Adjustment of Exercise Price and Number of Warrant Shares
Issuable. The Exercise Price and the number of Warrant Shares issuable upon the
exercise of each Warrant are subject to adjustment from time to time upon the
occurrence of the events enumerated in this Section 10. For purposes of this
Section 10, "Common Stock" means shares now or hereafter authorized of any class
of common stock of the Company and any other stock of the Company, however
designated, that has the right (subject to any prior rights of any class or
series of preferred stock) to participate in any distribution of the assets or
earnings of the Company without limit as to per share amount.

        (a) Adjustment for Change in Capital Stock.

               If the Company:

               (1) pays a dividend or makes a distribution on its Common Stock
        in shares of its Common Stock;

               (2) subdivides its outstanding shares of Common Stock into a
        greater number of shares; or

               (3) combines its outstanding shares of Common Stock into a
        smaller number of shares;

then the Exercise Price in effect immediately prior to such action shall then be
adjusted in accordance with the formula:

                                O
                      E' = E x --
                                A

            where:
            E' =   the adjusted Exercise Price

            E =    the current Exercise Price

            O = the number of Shares of Common Stock outstanding prior to such
            action

            A = the number of shares of Common Stock outstanding immediately
            after such action

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               In the case of a dividend or distribution, the adjustment shall
become effective immediately after the record date for determination of holders
of shares of Common Stock entitled to receive such dividend or distribution, and
in the case of a subdivision or combination, the adjustment shall become
effective immediately after the effective date of such corporate action.

               If after an adjustment a holder of a Warrant upon exercise of it
may receive shares of two or more classes of capital stock of the Company, the
Company shall determine the allocation of the adjusted Exercise Price between
the classes of capital stock. After such allocation, the exercise privilege, the
number of shares issuable upon such exercise, and the Exercise Price of each
class of capital stock shall thereafter be subject to adjustment on terms
comparable to those applicable to Common Stock in this Section 10.

               Such adjustment shall be made successively whenever any event
listed above shall occur in accordance with this Section 10(a).

        (b) Adjustment for Rights Issue.

               If the Company distributes any rights, options or warrants to any
holder of its Common Stock entitling such holder at any time after the record
date mentioned below to purchase shares of Common Stock at a price per share
less than the current market price per share on that record date, the Exercise
Price shall be adjusted in accordance with the formula:

                                                   N x P
                                           O  +    _____
                                                     M
                                E' = E x ____________________
                                               O + N

where:

               E' = the adjusted Exercise Price.

               E = the current Exercise Price.

               O = the number of Shares of Common Stock outstanding on the
                   record date.

               N = the number of additional shares of Common Stock issuable upon
                   exercise of the rights, options or warrants offered.

               P = the exercise price per share of the additional shares
                   issuable upon exercise of the rights, options or warrants.

               M = the current market price per share of Common Stock on the
                   record date.

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               The adjustment shall be made successively whenever any such
rights, options or warrants are issued and shall become effective immediately
after the record date for the determination of stockholders entitled to receive
the rights, options or warrants. If at the end of the period during which such
rights, options or warrants are exercisable, not all rights, options or warrants
shall have been exercised, the Exercise Price shall be immediately readjusted to
what it would have been if "N" in the above formula had been the number of
shares actually issued.

        (c) Adjustment for Other Distributions.

               If the Company distributes to any holder of its Common Stock any
of its assets (including but not limited to securities and cash), debt
securities, capital stock, or any rights or warrants to purchase assets, debt
securities, capital stock, or other securities of the Company, the Exercise
Price shall be adjusted in accordance with the formula:

                                              M  -  F
                                    E'=  E x ___________
                                                 M

where:

               E'= the adjusted Exercise Price.

               E = the current Exercise Price.

               M = the current market price per share of Common Stock on the
record date mentioned below.

               F = the Fair Market Value (as defined in Section 10(f)) on the
                   record date of the assets, debt securities, capital stock,
                   rights or warrants or other securities applicable to one
                   share of Common Stock.

               The adjustment shall be made successively whenever any such
distribution is made and shall become effective immediately after the record
date for the determination of stockholders entitled to receive the distribution.

               This subsection does not apply to (i) dividends, distributions,
subdivisions, or combinations referred to in subsection (a) of this Section 10,
(ii) rights, options or warrants referred to in subsection (b) of this Section
10, or (iii) ordinary course quarterly cash dividends distributed to all holders
of Common Stock.

        (d)Adjustment for Common Stock Issue.

               If the Company issues shares of Common Stock for a consideration
per share less than the current market price per share of Common Stock on the
date the Company fixes the offering price of such additional shares, the
Exercise Price shall be adjusted in accordance with the formula:

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<PAGE>   12

                                                          P
                                                  O  +  ____
                                                          M
                                      E' =  E x _________________
                                                         A

where:

               E' = the adjusted Exercise Price.

               E = the current Exercise Price.

               O = the number of shares outstanding immediately prior to the
                   issuance of such additional shares.

               P = the aggregate consideration received for issuance of such
                   additional shares.

               M = the current market price per share of Common Stock on the
                   date of issuance of such additional shares.

               A = the number of shares outstanding immediately after the
                   issuance of such additional shares.

               The adjustment shall be made successively whenever any such
issuance is made, and shall become effective immediately after such issuance.

               This subsection (d) does not apply to:

               (1) rights, options, warrants or other distributions referred to
        in subsections (b), (c) or (e) of this Section 10,

               (2) Common Stock issued to the Company's directors, employees and
        non-employee service providers under bona fide benefit plans, if such
        Common Stock would otherwise be covered by this subsection (d), or

               (3) Common Stock issued in a bona fide underwritten public
        offering.

        (e) Adjustment for Convertible Securities Issue.

               If the Company issues any securities convertible into or
exchangeable for Common Stock (other than securities issued in transactions
described in subsections (b) and (c) of this Section 10) for a consideration per
share of Common Stock initially deliverable upon conversion or exchange of such
securities less than the current market price per share of Common Stock on the
date of issuance of such securities, the Exercise Price shall be adjusted in
accordance with this formula:

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<PAGE>   13

                                                          P
                                                  O  +  ____
                                                          M
                                      E' =  E x _________________
                                                    O  +  D

where:

               E' = the adjusted Exercise Price.

               E = the then current Exercise Price.

               O = the number of shares outstanding immediately prior to the
                   issuance of such additional shares.

               P = the aggregate consideration received for issuance of such
                   securities.

               M = the current market price per share of Common Stock on the
                   date of issuance of such securities.

               D = the maximum number of shares deliverable upon conversion or
                   in exchange for such securities at the initial conversion or
                   exchange rate.

               The adjustment shall be made successively whenever any such
issuance is made, and shall become effective immediately after such issuance.

               If all of the Common Stock deliverable upon conversion or
exchange of such securities have not been issued when such securities are no
longer outstanding, then the Exercise Price shall promptly be readjusted to the
Exercise Price which would then be in effect had the adjustment upon the
issuance of such securities been made on the basis of the actual number of
shares of Common Stock issued upon conversion or exchange of such securities.

        (f) Current Market Price.

               (1) Current Market Price. In subsections (b), (c), (d) and (e) of
        this Section 10, the current market price per share of Common Stock on
        any date is:

                      (i) if the Common Stock is not registered under the
        Securities Exchange Act of 1934, as amended (the "Exchange Act"), then
        the Fair Market Value of the Common Stock based upon the Fair Market
        Value of 100% of the Company if sold as a going concern and without
        regard to any discount for the lack of liquidity or on the basis that
        the relevant shares of the Common Stock do not constitute a majority or
        controlling interest in the Company; or

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<PAGE>   14

                      (ii) if the Common Stock is registered under the Exchange
        Act, the average of the Quoted Prices of the Common Stock for no fewer
        than 10 consecutive trading days during a period of no more than 20
        consecutive trading days ending on the date in question. The "Quoted
        Price" of the Common Stock is the last reported sales price of the
        Common Stock as reported by NASDAQ National Market, or if the Common
        Stock is listed on a national securities exchange, the last reported
        sales price of the Common Stock on such exchange (which shall be for
        consolidated trading if applicable to such exchange), or if neither so
        reported or listed, the last reported bid price of the Common Stock. In
        the absence of one or more such quotations, the current market price of
        the Common Stock shall be determined as if the Common Stock was not
        registered under the Exchange Act.

               (2) Fair Market Value. Fair Market Value means the value
        obtainable upon a sale in an arm's-length transaction to a third party
        under usual and normal circumstances, with neither the buyer nor the
        seller under any compulsion to act, with equity to both, as determined
        by the Board in good faith; provided, however, that if the holder of a
        Warrant shall dispute the Fair Market Value as determined by the Board,
        such holder may undertake to have it and the Company retain an
        Independent Expert. The determination of Fair Market Value by the
        Independent Expert shall be final, binding and conclusive on the Company
        and such holder. All costs and expenses of the Independent Expert shall
        be borne by such holder unless the Fair Market Value as determined by
        the Independent Expert exceeds the Fair Market Value as determined by
        the Board by 5% but less than 10%, in which case the cost of the
        Independent Expert shall be shared equally by such holder and the
        Company, and unless the Fair Market Value as determined by the
        Independent Expert exceeds the Fair Market Value as determined by the
        Board by 10% or more, in which case the cost of the Independent Expert
        shall be borne solely by the Company.

               (3) Independent Expert. Independent Expert means a nationally
        recognized investment banking firm reasonably acceptable to the Company
        and the holder of this Warrant who does not (and whose affiliates do
        not) have a financial interest in the Company, any holder or any of
        their affiliates. For purposes of this Section 10(f)(3), an "affiliate"
        shall mean any such firm in which the Company or any holder owns or
        controls, directly or indirectly, a voting interest greater than 10% of
        the outstanding voting securities of such firm, or a firm which owns or
        controls, directly or indirectly, a voting interest greater than 10% of
        the outstanding voting securities of the Company or any holder.

        (g) Consideration Received.

               For purposes of any computations respecting consideration
received pursuant to subsections (d) and (e) of this Section 10, the following
shall apply:

                                       11
<PAGE>   15

               (1) in the case of the issuance of shares of Common Stock for
        cash, the consideration shall be the amount of such cash, provided that
        in no case shall any deduction be made for any commissions, discounts or
        other expenses incurred by the Company for any underwriting of the issue
        or otherwise in connection therewith;

               (2) in the case of the issuance of shares of Common Stock for a
        consideration in whole or in part other than cash, the consideration
        other than cash shall be deemed to be the fair market value thereof as
        determined in good faith by the Board (irrespective of the accounting
        treatment thereof), whose determination shall be conclusive, and
        described in a Board resolution; and

               (3) in the case of the issuance of securities convertible into or
        exchangeable for Common Stock, the aggregate consideration received
        therefore shall be deemed to be the consideration received by the
        Company for the issuance of such securities plus the additional minimum
        cash consideration, if any, to be received by the Company upon the
        conversion or exchange thereof (the consideration in each case to be
        determined in the same manner as provided in clauses (1) and (2) of this
        subsection).

        (h) When De Minimis Adjustment May Be Deferred.

               No adjustment in the Exercise Price need be made unless the
adjustment would require an increase or decrease of at least 1% in the Exercise
Price. Any adjustments that are not made shall be carried forward and taken into
account in any subsequent adjustment.

               All calculations under this Section shall be made to the nearest
cent or to the nearest 1/100th of a share, as the case may be.

        (i) When No Adjustment Required.

               No adjustment need be made for rights to purchase Common Stock
pursuant to a Company plan for reinvestment of dividends or interest.

               No adjustment need be made for a change in the par value or no
par value of the Common Stock.

               To the extent Warrants become convertible into cash, no
adjustment need be made thereafter as to the cash. Interest will not accrue on
the cash.

        (j) Notice of Adjustment.

               Whenever the Exercise Price is adjusted, the Company shall
provide the notices required by Section 14 hereof.

                                       12
<PAGE>   16

        (k) Voluntary Reduction.

               The Company from time to time may reduce the Exercise 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; provided, however, that in no event
may the Exercise Price be less than the par value of a share of Common Stock.

               Whenever the Exercise Price is reduced, the Company shall mail to
Warrant holders a notice of the reduction. The Company shall mail the notice at
least 15 days before the date the reduced Exercise Price takes effect. The
notice shall state the reduced Exercise Price and the period it will be in
effect.

               A reduction of the Exercise Price does not change or adjust the
Exercise Price otherwise in effect for purposes of subsections (a), (b), (c),
(d) and (e) of this Section 10.

        (l) Reorganization of Company.

               If any reclassification of the Common Stock of the Company or any
consolidation or merger of the Company with another entity, or the sale or lease
of all or substantially all of the Company's assets to another entity shall be
effected in such a way that holders of the Common Stock of the Company shall be
entitled to receive stock, securities or assets with respect to or in exchange
for such Common Stock, then, as a condition precedent to such reclassification,
consolidation, merger, sale or lease, lawful and adequate provisions shall be
made whereby the Warrant holder shall thereafter have the right to purchase and
receive upon the basis and the terms and conditions specified in this Agreement
and in lieu of the shares of Common Stock immediately theretofore purchasable
and receivable upon the exercise of the rights represented hereby, such shares
of stock, securities or assets as may be issued or payable in such
reclassification, consolidation, merger, sale or lease with respect to or in
exchange for the number of shares of Common Stock purchasable and receivable
upon the exercise of the rights represented hereby had such rights been
exercised immediately prior thereto, and in any such case appropriate provision
shall be made with respect to the rights and interests of the holders of the
Warrants to the end that the provisions hereof (including without limitation
provisions for adjustments of the Exercise Price and of the number of shares of
Common Stock purchasable and receivable upon the exercise of the Warrant) shall
thereafter be applicable, as nearly as may be, in relation to any shares of
stock, securities or assets thereafter deliverable upon the exercise hereof. The
Company will not effect any such reclassification, consolidation, merger, sale
or lease, unless prior to the consummation thereof the successor corporation (if
other than the Company) resulting from such reclassification, consolidation or
merger or the corporation purchasing or leasing such assets shall assume by a
supplemental Warrant Agreement, executed and mailed or delivered to the holders
of the Warrants at the last address thereof appearing on the books of Company,
the obligation to deliver to such holders such shares of stock, securities or
assets as, in accordance with the foregoing provisions, such holders may be
entitled to purchase.

                                       13
<PAGE>   17

               If the issuer of securities deliverable upon exercise of Warrants
under the supplemental Warrant Agreement is an affiliate of the formed,
surviving, transferee or lessee corporation, that issuer shall join in the
supplemental Warrant Agreement.

               If this subsection (1) applies, subsections (a), (b), (c), (d)
and (e) of this Section 10 do not apply.

        (m) When Issuance or Payment May Be Deferred.

               In any case in which this Section 10 shall require that an
adjustment in the Exercise Price be made effective as of a record date for a
specified event, the Company may elect to defer until the occurrence of such
event (i) issuing to the holder of any Warrant exercised after such record date
the Warrant Shares and other capital stock of the Company, if any, issuable upon
such exercise over and above the Warrant Shares and other capital stock of the
Company, if any, issuable upon such exercise on the basis of the Exercise Price
and (ii) paying to such holder any amount in cash in lieu of a fractional share
pursuant to Section 11; provided, however, that the Company shall deliver to
such holder a due bill or other appropriate instrument evidencing such holder's
right to receive such additional Warrant Shares, other capital stock and cash
upon the occurrence of the event requiring such adjustment.

        (n) Adjustment in Number of Shares.

               Upon each adjustment of the Exercise Price pursuant to this
Section 10, each Warrant outstanding prior to the making of the adjustment in
the Exercise Price shall thereafter evidence the right to receive upon payment
of the adjusted Exercise Price that number of shares of Common Stock (calculated
to the nearest hundredth) obtained from the following formula:

                                                    E
                                      N'  =  N x ______
                                                    E'
where:

               N'= the adjusted number of Warrant Shares issuable upon exercise
                   of a Warrant by payment of the adjusted Exercise Price.

               N = the number of Warrant Shares previously issuable upon
                   exercise of a Warrant by payment of the adjusted Exercise
                   Price.

               E' = the adjusted Exercise Price.

               E = the Exercise Price prior to adjustment.

                                       14
<PAGE>   18

        (o) Form of Warrants.

               Irrespective of any adjustments in the Exercise Price or the
number or kind of shares purchasable upon the exercise of the Warrants, Warrants
theretofore or thereafter issued may continue to express the same price and
number and kind of shares as are stated in the Warrants initially issuable
pursuant to this Agreement.

        SECTION 11. Fractional Interests. The Company shall not be required to
issue fractional Warrant Shares on the exercise of Warrants. If more than one
Warrant shall be presented for exercise in full at the same time by the same
holder, the number of full Warrant Shares which shall be issuable upon the
exercise thereof shall be computed on the basis of the aggregate number of
Warrant Shares purchasable on exercise of the Warrants so presented. If any
fraction of a Warrant Share would, except for the provisions of this Section 11,
be issuable on the exercise of any Warrants (or specified portion thereof), the
number of Warrant Shares which shall be issued by the Company on exercise of
such Warrants shall be rounded (i) to the last previous whole number if the
fraction is less than 0.5 of a Warrant Share or (ii) to the next higher whole
number if the fraction is greater than or equal to 0.5 of a Warrant Share.

        SECTION 12. Representations and Warranties of the Company. The Company
represents and warrants to each of the Banks, as of the date hereof, as follows:

        (a) Corporate Organization.

               The Company is duly organized, validly existing and in good
standing under the laws of the state of its formation. The Company is also duly
authorized, qualified and licensed in all applicable jurisdictions, and under
all applicable laws, regulations, ordinances or orders of public authorities, to
carry on its business in the locations and in the manner presently conducted, to
the extent that the failure to do so would not reasonably be expected to
materially adversely affect the consolidated financial condition or operations
of the Company and could not reasonably be expected to have a material adverse
effect on the Company's ability to perform its obligations under the Restructure
Loan Documents (as defined in the Loan Restructure Agreement), having regard for
its other financial obligations.

        (b) Authorization.

               The execution, delivery and performance by the Company of this
Agreement and the Registration Rights Agreement of even date hereof between the
parties hereto (the "Registration Rights Agreement," and, together with this
Agreement, the "Warrant Documents"), and the issuance by the Company of the
Warrants, are within the Company's corporate powers, have been duly authorized
by all necessary corporate action and do not contravene (i) the Company's
certificate of incorporation, bylaws or other organizational documents or (ii)
any law or regulation or any contractual restriction binding on or affecting the
Company.

                                       15
<PAGE>   19

        (c) Governmental Consents.

               No authorization or approval or other action by, and no notice to
or filing with, any governmental authority or regulatory body (except routine
reports required pursuant to the Securities Exchange Act of 1934, as amended (if
such act is applicable to the Company), which reports will be made in the
ordinary course of business) is required for the due execution, delivery and
performance by the Company of the Warrant Documents or for the issuance by the
Company of the Warrants or the Warrant Shares.

        (d) Validity.

               The Warrant Documents are the binding obligations of the Company,
enforceable in accordance with their respective terms and when executed and
delivered by the Company in accordance with the terms hereof, the Warrants will
constitute a legally valid and binding obligation of the Company; except in each
case as such enforceability may be limited by bankruptcy, insolvency,
reorganization, liquidation, moratorium or other similar laws of general
application and equitable principles relating to or affecting creditors' rights.

        (e) Not an Investment Company.

               The Company is not an "investment company" within the meaning of
the Investment Company Act of 1940, as amended.

        (f) Reports.

               The Company has filed all required forms, reports and documents
with the Securities and Exchange Commission (the "SEC") since January 1, 1997
(collectively, the "SEC Reports"), all of which have complied in all material
respects with all applicable requirements of the Securities Act of 1933, as
amended (the "Securities Act") and the Exchange Act. Except as set forth in
subsequent filings with the SEC, none of the SEC Reports, including without
limitation any financial statements or schedules including therein, contained
any untrue statement of a material fact or omitted to state a material fact
required to be stated therein or necessary in order to make the statements
therein not misleading. Each of the balance sheets (including the related notes)
included in the SEC Reports fairly presents the consolidated financial position
of the Company and its consolidated subsidiaries as of the respective dates
thereof, and the other related statements (including the related notes) included
therein fairly present the results of operations and the changes in financial
position of the Company and its consolidated subsidiaries for the respective
fiscal years, except, in the case of interim financial statements, for year-end
audit adjustments, consisting only of normal recurring accruals. Each of the
financial statements (including the related notes) included in the SEC Reports
has been prepared in accordance with generally accepted accounting principles
consistently applied during the periods involved, except as otherwise noted
therein.

                                       16
<PAGE>   20

        (g) Authorized Shares.

               As of May 10, 2000, (i) the Company has 151,000,000 authorized
shares of capital stock, of which 66,054,041 shares of Common Stock and no
shares of Preferred Stock are issued and outstanding, (ii) the Company has
83,945,959 authorized but unissued shares of Common Stock which will be required
to be issued to satisfy conversions or exercises of the Warrants, (iii) the
Series A Warrants are exercisable into a number of shares of Common Stock equal
to, in the aggregate, 2.5% of the issued and outstanding Common Stock, and (iv)
the Series B Warrants are exercisable into a number of shares of Common Stock
equal to, in the aggregate, 1% of the issued and outstanding Common Stock.

        (h) Status of the Warrants and the Warrant Shares.

               Upon issuance hereunder, the Warrants will be validly issued and
outstanding, fully paid and nonassessable, and the issuance thereof is not
subject to preemptive rights of any other stockholder of the Company. The
Warrant Shares will be duly authorized by all necessary corporate action on the
part of the Company (no consent or approval of stockholders being required by
law, the corporate documents of the Company, the qualification criteria of any
securities exchange or market or otherwise), and upon issuance in accordance
with the terms of this Agreement, will be validly issued and outstanding, fully
paid and nonassessable, and the issuance thereof is not subject to preemptive
rights of any other stockholder of the Company. The Warrant Shares have been
validly reserved for issuance upon the exercise of the Warrants.

        SECTION 13. Purchase for Investment; Authority; Binding Agreement . Each
of the Banks represents and warrants to the Company that:

        (a) such Bank is an Accredited Investor within the meaning of Rule
501(a) under the Securities Act and the Warrants to be acquired by it pursuant
to this Agreement are being acquired for its own account for investment and
without intent to resell, and such Bank will not offer, sell, transfer, pledge,
hypothecate or otherwise dispose of any of such Warrants, unless pursuant to a
transaction either registered under, or exempt from registration under, the
Securities Act;

        (b) the execution, delivery and performance of each of the Warrant
Documents and the receipt of the Warrants pursuant hereto are within such Bank's
corporate powers and has been duly and validly authorized by all requisite
corporate action;

        (c) each of the Warrant Documents has been duly executed and delivered
by such Bank;

        (d) each of the Warrant Documents constitutes a legally valid and
binding agreement of such Bank; and

                                       17
<PAGE>   21

        (e) such Bank has knowledge and experience in financial and business
matters so as to be capable of evaluating the merits and risks of its
investments in the Warrants and such Bank is capable of bearing the economic
risks of such investments.

        SECTION 14. Notices to Warrant Holders. Upon any adjustment of the
Exercise Price pursuant to Section 10, the Company shall promptly thereafter (i)
cause the Company's Chief Financial Officer to execute a certificate setting
forth the Exercise Price after such adjustment and setting forth in reasonable
detail the method of calculation and the facts upon which such calculations are
based and setting forth the number of Warrant Shares (or portion thereof)
issuable after such adjustment in the Exercise Price, upon exercise of a Warrant
and payment of the adjusted Exercise Price, and (ii) cause to be given to each
of the registered holders of the Warrant Certificates at his address appearing
on the Warrant register written notice of such adjustments by first-class mail,
postage prepaid. Where appropriate, such notice may be given in advance and
included as a part of the notice required to be mailed under the other
provisions of this Section 14.

        In case:

        (a) the Company shall authorize the issuance to all holders of shares of
Common Stock of rights, options or warrants to subscribe for or purchase shares
off Common Stock or of any other subscription rights or warrants; or

        (b) the Company shall authorize the distribution to all holders of
shares of Common Stock of evidences of its indebtedness or assets (other than
cash dividends or cash distributions payable out of earnings or earned surplus
or dividends or distributions payable in shares of Common Stock); or

        (c) of any consolidation or merger to which the Company is a party and
for which approval of any shareholders of the Company is required, or of the
conveyance or transfer of all or substantially all of the properties and assets
of the Company, or of any reclassification or change of Common Stock issuable
upon exercise of the Warrants (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 a tender offer or exchange offer for shares of
Common Stock; or

        (d) of the voluntary or involuntary dissolution, liquidation or winding
up of the Company; or

        (e) the Company proposes to take any action that would require an
adjustment in the Exercise Price pursuant to subsections (a), (b), (c), (d) or
(e) of Section 10, or if the Company takes any action that would require a
supplemental Warrant Agreement pursuant to subsection (1) of Section 10.

then the Company shall cause to be given to each of the registered holders of
the Warrant Certificates at his address appearing on the Warrant register, at
least 20 days (or 10 days in any case specified in clauses (a), (b) or (c)
above) prior to the applicable record date hereinafter

                                       18
<PAGE>   22

specified, or promptly in the case of events for which there is no record date,
by first-class mail, postage prepaid, a written notice stating (i) the date as
of which the holders of record of shares of Common Stock to be entitled to
receive any such rights, options, warrants or distribution are to be determined,
or (ii) the initial expiration date set forth in any tender offer or exchange
offer for shares of Common Stock, or (iii) the date on which any such
consolidation, merger, conveyance, transfer, dissolution, liquidation or winding
up is expected to become effective or consummated, and the date as of which it
is expected that holders of record of shares of Common Stock shall be entitled
to exchange such shares for securities or other property, if any, deliverable
upon such reclassification, consolidation, merger, conveyance, transfer,
dissolution, liquidation or winding up. The failure to give the notice required
by this Section 14 or any defect therein shall not affect the legality or
validity of any distribution, right, option, warrant, consolidation, merger,
conveyance, transfer, dissolution, liquidation or winding up, or the vote upon
any action.

        Nothing contained in this Agreement or in any of the Warrants shall be
construed as conferring upon the holders thereof the right to vote or to consent
or to receive notice as shareholders in respect of the meetings of shareholders
or the election of Directors of the Company or any other matter, or any rights
whatsoever as shareholders of the Company.

        SECTION 15. Notices to Company and Warrant Holder. Any notice or demand
authorized by this Agreement to be given or made by the registered holder of any
Warrant Certificate to or on the Company shall be sufficiently given or made
when and if deposited in the mail, first class or registered, postage prepaid,
addressed to the office of the Company expressly designated by the Company at
its office for purposes of this Agreement (until the Warrant holders are
otherwise notified in accordance with this Section by the Company), as follows:

                      Komag, Incorporated
                      1710 Automation Parkway
                      San Jose, California 95131-1873
                      Facsimile:  408-944-9234
                      Attn:  Chief Financial Officer

        Any notice pursuant to this Agreement to be given by the Company to the
registered holder(s) of any Warrant Certificate shall be sufficiently given when
and if deposited in the mail, first-class or registered, postage prepaid,
addressed (until the Company is otherwise notified in accordance with this
Section by such holder) to such holder at the address appearing on the Warrant
register of the Company.

        SECTION 16. Supplements and Amendments. The Company may not supplement
or amend this Agreement without the prior written approval of the holders of
Warrants representing at least 51% of the aggregate outstanding Warrants
affected by such supplement or amendment; provided however, that without the
written approval of the holders of all Warrants affected by such supplement or
amendment, no supplement or amendment shall do any of the following:

        (a) reduce the number of Warrant Shares for which the Warrants may be
exercised;

                                       19
<PAGE>   23

        (b) amend the provisions of Section 10 of this Agreement;

        (c) except as expressly provided in Section 10(a)(3) of this Agreement,
increase the Exercise Price applicable to the Warrants;

        (d) reduce the duration of the Warrants;

        (e) extend the issuance date of the Series B Warrants; or

        (f) amend the provisions of this Section 16.

        SECTION 17. Successors. All the covenants and provisions of this
Agreement by or for the benefit of the Company shall bind and inure to the
benefit of its respective successors and assigns hereunder.

        SECTION 18. Governing Law. This Agreement and each Warrant Certificate
issued hereunder shall be deemed to be a contract made under the laws of the
State of California and for all purposes shall be construed in accordance with
the internal laws of said State.

        SECTION 19. Benefits of This Agreement. Nothing in this Agreement shall
be construed to give to any person or corporation other than the Company and the
registered holders of the Warrant Certificates any legal or equitable right,
remedy or claim under this Agreement; but this Agreement shall be for the sole
and exclusive benefit of the Company and the registered holders of the Warrant
Certificates.

        SECTION 20. Counterparts. This Agreement may be executed in any number
of counterparts and each of such counterparts shall for all purposes be deemed
to be an original, and all such counterparts shall together constitute but one
and the same instrument.

                            [Signature Pages Follow]

                                       20
<PAGE>   24

        IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed, as of the day and year first above written.

KOMAG, INCORPORATED

By:
   ----------------------------------
Title:
      -------------------------------

Address:
1710 Automation Parkway
San Jose, California 95131-1873
Facsimile: (408) 944-9234
Attention:  Chief Financial Officer

FLEET NATIONAL BANK f/k/a BANKBOSTON, N.A.,
as Restructure Agent and as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
100 Federal Street, Mail Stop 01-06-01
Boston, MA 02110
Facsimile:  (617) 434-4775
Attention:  Donald Sheehan

BANK OF MONTREAL, as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
115 S. LaSalle Street, 12 West
Chicago, IL 60603
Facsimile:  (312) 750-6057
Attention:  Jack J. Kane

                                      S-1
<PAGE>   25

BEAR, STEARNS & CO. INC.,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
245 Park Avenue
New York, New York  10167
Facsimile:  (212) 272-8102
Attention:

COMERICA BANK - CALIFORNIA,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
55 Almaden Boulevard
Mail Code: 4041
San Jose, California  95113
Facsimile: (408) 556-5855
Attention:  Carol A. Palestro

OLYMPUS SECURITIES, LTD.,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
c/o Citadel Investment Group, LLC
225 West Washington Street, 9th Floor
Chicago, Illinois  60606
Facsimile:  (312) 368-4650
Attention:  Bradford Couri

                                      S-2
<PAGE>   26

NELSON PARTNERS LTD.,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
c/o Citadel Investment Group, LLC
225 West Washington Street, 9th Floor
Chicago, Illinois  60606
Facsimile:  (312) 368-4650
Attention:  Bradford Couri

THE BANK OF NOVA SCOTIA,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
One Liberty Plaza
New York, New York 10006
Facsimile:  (212) 225-5205
Attention:  Norm Gillespie

UNION BANK OF CALIFORNIA, N.A.,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
350 California Street, 7th Floor
San Francisco, California  94104
Facsimile:  (415) 705-7390
Attention:  Christiana Creekpaum

                                      S-3
<PAGE>   27

LOEB PARTNERS CORPORATION,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
61 Broadway, 24th Floor
New York, New York  10006
Facsimile:  (212) 574-2003
Attention:  Robert Grubin

THE DAI-ICHI KANGYO BANK, LIMITED,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
Corporate Finance Department I
One World Trade Center, Suite 4911
New York, NY 10048
Facsimile:  (212) 912-1879
Attention:  Nelson Chang

THE INDUSTRIAL BANK OF JAPAN, LIMITED,
SAN FRANCISCO AGENCY,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
555 California Street, Suite 3110
San Francisco, California  94104
Facsimile:  (415) 982-1917
Attention:  Joseph A. Endoso

                                      S-4
<PAGE>   28

THE MITSUBISHI TRUST AND BANKING CORPORATION,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
520 Madison Avenue, 26th Floor
New York, New York  10022
Facsimile:  (212) 644-6825
Attention:  Daniel Chang

SANWA BANK CALIFORNIA,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
444 Market Street, 22nd Floor
San Francisco, CA 94111
Facsimile:  (415) 597-5491
Attention:  George Vetek

THE FIRST NATIONAL BANK OF CHICAGO,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
The First National Bank of Chicago
c/o Bank One
Western Region Managed Assets
AZ1-1283
201 N. Central Avenue
Phoenix, AZ 85004-2267
Facsimile:  (602) 221-1737
Attention:  Dennis Warren

                                      S-5
<PAGE>   29

THE FUJI BANK, LIMITED,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
333 South Hope Street, 39th Floor
Los Angeles, CA 90071
Facsimile:  (213) 253-4178
Attention:

THE SUMITOMO BANK, LIMITED,
as a Restructure Lender

By:
   ----------------------------------
Title:
      -------------------------------

Address:
555 California Street, Suite 3350
San Francisco, California  94104
Facsimile:  (415) 398-3580
Attention:  Azar Shakeri

                                      S-6
<PAGE>   30

                                                                      SCHEDULE 1

BANK                                                              WARRANT SHARES
----                                                              --------------
Fleet National Bank f/k/a/ BankBoston, N.A.................................
Bank of Montreal...........................................................
Bear, Stearns & Co. Inc....................................................
Comerica Bank - California.................................................
Olympus Securities, Ltd....................................................
Nelson Partners Ltd.
The Bank of Nova Scotia....................................................
Union Bank of California, N.A..............................................
Loeb Partners Corporation
The Dai-Ichi Kangyo Bank, Limited..........................................
The Industrial Bank of Japan, Limited, San Francisco Agency................
The Mitsubishi Trust and Banking Corporation...............................
Sanwa Bank California......................................................
The First National Bank of Chicago.........................................
The Fuji Bank, Limited.....................................................
The Sumitomo Bank, Limited.................................................

                                  Schedule - 1
<PAGE>   31

                                                                       EXHIBIT A

                          [Form of Warrant Certificate]

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933 OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR AN APPLICABLE
EXEMPTION TO THE REGISTRATION REQUIREMENT OF SUCH ACT OR SUCH LAWS. SUCH SALE OR
OTHER DISPOSITION MUST ALSO BE IN COMPLIANCE WITH THE RESTRICTIONS ON TRANSFER
SET FORTH IN THE WARRANT AGREEMENT DATED AS OF MAY 25, 2000, A COPY OF WHICH MAY
BE OBTAINED FROM KOMAG, INCORPORATED AT ITS PRINCIPAL EXECUTIVE OFFICE.

                     EXERCISABLE ON OR AFTER THE DATE HEREOF
                          AND ON OR BEFORE MAY 25, 2010

No.                                                        ___ Series A Warrants
                          Series A Warrant Certificate

                               KOMAG, INCORPORATED

        This Warrant Certificate certifies that _________________, or registered
assigns, is the registered holder of ___ Series A Warrants expiring May 25, 2010
(the "Warrants") to purchase Common Stock, $0.01 par value (the "Common Stock"),
of Komag, Incorporated, a Delaware corporation (the "Company"). Each Series A
Warrant entitles the holder upon exercise on or after the date hereof to receive
from the Company on or before 5:00 p.m., Los Angeles time, on May 25, 2010, one
fully paid and nonassessable share of Common Stock (a "Warrant Share") at the
initial exercise price (the "Exercise Price") of $_______ payable as otherwise
provided in the Warrant Agreement referred to below, upon surrender of this
Warrant Certificate and payment of the Exercise Price at the office of the
Company designated for such purpose, but only subject to the conditions set
forth herein and in the Warrant Agreement. The Exercise Price and number of
Warrant Shares issuable upon exercise of the Warrants are subject to adjustment
upon the occurrence of certain events set forth in the Warrant Agreement.

        No Warrant may be exercised after 5:00 p.m., Los Angeles time, on May
25, 2010, and to the extent not exercised by such time such Warrants shall
become void.

        The Series A Warrants evidenced by this Warrant Certificate are part of
a duly authorized issue of Warrants expiring May 25, 2010 entitling the holder
on exercise to receive shares of Common Stock of the Company, and are issued
pursuant to a Warrant Agreement dated as of the date hereof (the "Warrant
Agreement"), duly executed and delivered by the Company, which Warrant Agreement
is hereby incorporated by reference in and made a part of this instrument and is
hereby referred to for a description of the rights, limitation of rights,
obligations, duties and

                                       A-1
<PAGE>   32

immunities thereunder of the Company and the holders (the words "holders" or
"holder" meaning the registered holders or registered holder) of the Warrants. A
copy of the Warrant Agreement may be obtained by the holder hereof upon written
request to the Company.

        Warrants may be exercised at any time on or before May 25, 2010. The
holder of Warrants evidenced by this Warrant Certificate may exercise them by
surrendering this Warrant Certificate, with the form of election to purchase set
forth hereon properly completed and executed, together with payment of the
Exercise Price at the office of the Company designated for such purpose. In the
event that upon any exercise of Warrants evidenced hereby the number of Warrants
exercised shall be less than the total number of Warrants evidenced hereby,
there shall be issued to the holder hereof or his assignee a new Warrant
Certificate evidencing the number of Warrants not exercised. No adjustment shall
be made for any dividends on any Common Stock issuable upon exercise of this
Warrant.

        The Warrant Agreement provides that upon the occurrence of certain
events the Exercise Price set forth on the face hereof may, subject to certain
conditions, be adjusted. If the Exercise Price is adjusted, the Warrant
Agreement provides that the number of shares of Common Stock issuable upon the
exercise of each Warrant shall be adjusted. No fractions of a share of Common
Stock will be issued upon the exercise of any Warrant, but the Company will pay
the cash value thereof determined as provided in the Warrant Agreement.

        The holders of the Warrants are entitled to certain registration rights
with respect to the Common Stock purchasable upon exercise thereof. Said
registration rights are set forth in full in the Registration Rights Agreement
dated as of the date hereof, between the Company and the Banks identified in the
Warrant Agreement. A copy of the Registration Rights Agreement may be obtained
by the holder hereof upon written request to the Company.

        Warrant Certificates, when surrendered at the office of the Company by
the registered holder thereof in person or by legal representative or attorney
duly authorized in writing, may be exchanged, in the manner and subject to the
limitations provided in the Warrant Agreement, but without payment of any
service charge, for another Warrant Certificate or Warrant Certificates of like
tenor evidencing in the aggregate a like number of Warrants.

        Upon due presentation for registration of transfer of this Warrant
Certificate at the office of the Company, a new Warrant Certificate or Warrant
Certificates of like tenor and evidencing in the aggregate a like number of
Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided in the Warrant Agreement,
without charge except for any tax or other governmental charge imposed in
connection therewith.

        The Company may deem to treat the registered holder(s) thereof as the
absolute owner(s) of this Warrant Certificate (notwithstanding any notation of
ownership or other writing hereon made by anyone), for the purpose of any
exercise hereof, of any distribution to the holder(s) hereof, and for all other
purposes, and the Company shall not be affected by an y notice to the contrary.
Neither the Warrants nor this Warrant Certificate entitles any holder hereof to
any rights of a stockholder of the Company.

                                      A-2
<PAGE>   33

        This Warrant Certificate shall not be valid unless countersigned by the
Company, as such term is used in the Warrant Agreement.

                           [Signature Page to Follow]

                                      A-3
<PAGE>   34

        IN WITNESS WHEREOF, the Company has caused this Warrant certificate to
be signed by its President and by its Secretary and has caused its corporate
seal to be affixed hereunto or imprinted hereon.

                                     KOMAG, INCORPORATED,
                                     a Delaware corporation

                                     -------------------------------------------
                                     Name:
                                     Title:

                                      A-4
<PAGE>   35

                               [Form of Election]

                    (To Be Executed Upon Exercise of Warrant)

        The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to receive _________ shares of Common
Stock and herewith tenders payment for such shares to the order of Komag,
Incorporated in the amount of $________ as follows: (check applicable box)

        [ ] in the form of cash or in immediately available funds payable to the
order of the Company

      * [ ] in lieu of cash, net shares of Common Stock calculated as follows:

            Current Market Price - Exercise Price
            ---------------------------------------  x  Warrant Shares Exercised
                    Current Market Price

        The undersigned requests that a certificate for such shares be
registered in the name of ________________, whose address is
____________________________ and that such shares be delivered to
________________ whose address is ________________________. If said number of
shares is less than all of the shares of Common Stock purchasable hereunder, the
undersigned requests that a new Warrant Certificate representing the remaining
balance of such shares be registered in the name of _____________, whose address
is ___________________________, and that such Warrant Certificate be delivered
to _________________, whose address is _____________________.

                                      Signature: _______________________________

Date: ________________

                                      Signature Guaranteed: ____________________

* Please note that this is the only form of payment available if this Warrant
Certificate is to be exercised within two years of its issuance.

                                      A-5
<PAGE>   36

                              [Form of Assignment]

                   (To Be Executed Upon Assignment of Warrant)

        If you, the holder, want to assign this Warrant, fill in the form below
and have your signature guaranteed:

        For value received, I or we assign and transfer this Warrant to:

--------------------------------------------------------------------------------
                      (INSERT ASSIGNEE'S SOCIAL SECURITY OR
                           TAX IDENTIFICATION NUMBER)

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

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

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

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

--------------------------------------------------------------------------------
              (Print or type assignee's name, address and zip code)

and appoints ______________________________________________________ agent to
transfer this security on the books of the Company. The agent may substitute
another to act for him.

        In connection with the transfer of this Warrant, the undersigned
        certifies that:

        (Check one)

           [ ] This Warrant is being transferred to Komag, Incorporated.

           [ ] This Warrant is being transferred to a person or entity other
               than Komag, Incorporated, in connection with which the Company
               has received an opinion of counsel (satisfactory to it in form
               and substance) to the effect that the transfer is being made
               pursuant to an exemption from, or in a transaction not subject
               to, the registration requirements of the Securities Act.

Date: __________________________________________________________________________

Your signature: ________________________________________________________________
                (Sign exactly as your name appears on this Warrant)

Signature Guaranteed by *: _____________________________________________________

* Signature must be guaranteed by an eligible guarantor institution within the
meaning of Securities and Exchange Commission Rule 17Ad-15 (including banks,
stock brokers, savings and loan associations, national securities exchanges,
registered securities associations, clearing agencies and credit unions) with
membership or participation in the Securities Transfer Agents Medallion Program
("STAMP") or such other signature guarantee medallion program as may be approved
by the Registrar in addition to, or substitution for, STAMP, if this Security is
to be delivered other than to and in the name of the registered holder.

IF NONE OF THE FOREGOING BOXES IS CHECKED, THE TRUSTEE SHALL NOT BE OBLIGATED TO
REGISTER THE TRANSFER OF THIS SECURITY UNLESS AND UNTIL THE CONDITIONS TO ANY
SUCH TRANSFER OF REGISTRATION SET FORTH HEREIN, ON THE FACE HEREOF AND IN THE
WARRANT AGREEMENT SHALL HAVE BEEN SATISFIED.

                                      A-6
<PAGE>   37

                                                                       EXHIBIT B

                          [Form of Warrant Certificate]

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933 OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR AN APPLICABLE
EXEMPTION TO THE REGISTRATION REQUIREMENT OF SUCH ACT OR SUCH LAWS. SUCH SALE OR
OTHER DISPOSITION MUST ALSO BE IN COMPLIANCE WITH THE RESTRICTIONS ON TRANSFER
SET FORTH IN THE WARRANT AGREEMENT DATED AS OF MAY 25, 2000, A COPY OF WHICH MAY
BE OBTAINED FROM KOMAG, INCORPORATED AT ITS PRINCIPAL EXECUTIVE OFFICE.

                      EXERCISABLE ON OR AFTER MAY 25, 2001
                          AND ON OR BEFORE MAY 25, 2011

No.                                                        ___ Series B Warrants
                          Series B Warrant Certificate

                               KOMAG, INCORPORATED

        This Warrant Certificate certifies that _________________, or registered
assigns, is the registered holder of ___ Series B Warrants expiring not later
than May 25, 2011 (the "Warrants") to purchase Common Stock, $0.01 par value
(the "Common Stock"), of Komag, Incorporated, a Delaware corporation (the
"Company"). Each Series B Warrant entitles the holder upon exercise on or after
May 25, 2001 to receive from the Company on or before 5:00 p.m., Los Angeles
time, on May 25, 2011, unless earlier terminated, one fully paid and
nonassessable share of Common Stock (a "Warrant Share") at the initial exercise
price (the "Exercise Price") of $_______ payable as otherwise provided in the
Warrant Agreement referred to below, upon surrender of this Warrant Certificate
and payment of the Exercise Price at the office of the Company designated for
such purpose, but only subject to the conditions set forth herein and in the
Warrant Agreement. The Exercise Price and number of Warrant Shares issuable upon
exercise of the Warrants are subject to adjustment upon the occurrence of
certain events set forth in the Warrant Agreement.

        Notwithstanding anything to the contrary in this Warrant Certificate,
the Series B Warrants shall become void and all rights thereunder and all rights
in respect thereof under this Warrant Certificate shall cease if the unpaid loan
balances on the notes issued pursuant to the Credit Facilities, in the
aggregate, does not exceed $160 million.

        No Warrant may be exercised after 5:00 p.m., Los Angeles time, on May
25, 2011, and to the extent not exercised by such time such Warrants shall
become void.

                                      B-1
<PAGE>   38

        The Series B Warrants evidenced by this Warrant Certificate are part of
a duly authorized issue of Warrants expiring May 25, 2011 entitling the holder
on exercise to receive shares of Common Stock, $0.01 par value, of the Company
(the "Common Stock"), and are issued pursuant to a Warrant Agreement dated as of
the date hereof (the "Warrant Agreement"), duly executed and delivered by the
Company, which Warrant Agreement is hereby incorporated by reference in and made
a part of this instrument and is hereby referred to for a description of the
rights, limitation of rights, obligations, duties and immunities thereunder of
the Company and the holders (the words "holders" or "holder" meaning the
registered holders or registered holder) of the Warrants. A copy of the Warrant
Agreement may be obtained by the holder hereof upon written request to the
Company.

        Warrants may be exercised at any time on or after May 25, 2001 and on or
before May 25, 2011. The holder of Warrants evidenced by this Warrant
Certificate may exercise them by surrendering this Warrant Certificate, with the
form of election to purchase set forth hereon properly completed and executed,
together with payment of the Exercise Price at the office of the Company
designated for such purpose. In the event that upon any exercise of Warrants
evidenced hereby the number of Warrants exercised shall be less than the total
number of Warrants evidenced hereby, there shall be issued to the holder hereof
or his assignee a new Warrant Certificate evidencing the number of Warrants not
exercised. No adjustment shall be made for any dividends on any Common Stock
issuable upon exercise of this Warrant.

        The Warrant Agreement provides that upon the occurrence of certain
events the Exercise Price set forth on the face hereof may, subject to certain
conditions, be adjusted. If the Exercise Price is adjusted, the Warrant
Agreement provides that the number of shares of Common Stock issuable upon the
exercise of each Warrant shall be adjusted. No fractions of a share of Common
Stock will be issued upon the exercise of any Warrant, but the Company will pay
the cash value thereof determined as provided in the Warrant Agreement.

        The holders of the Warrants are entitled to certain registration rights
with respect to the Common Stock purchasable upon exercise thereof. Said
registration rights are set forth in full in the Registration Rights Agreement
dated as of the date hereof, between the Company and the Banks identified in the
Warrant Agreement. A copy of the Registration Rights Agreement may be obtained
by the holder hereof upon written request to the Company.

        Warrant Certificates, when surrendered at the office of the Company by
the registered holder thereof in person or by legal representative or attorney
duly authorized in writing, may be exchanged, in the manner and subject to the
limitations provided in the Warrant Agreement, but without payment of any
service charge, for another Warrant Certificate or Warrant Certificates of like
tenor evidencing in the aggregate a like number of Warrants.

        Upon due presentation for registration of transfer of this Warrant
Certificate at the office of the Company, a new Warrant Certificate or Warrant
Certificates of like tenor and evidencing in the aggregate a like number of
Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided in the Warrant Agreement,
without charge except for any tax or other governmental charge imposed in
connection therewith.

                                      B-2
<PAGE>   39

        The Company may deem to treat the registered holder(s) thereof as the
absolute owner(s) of this Warrant Certificate (notwithstanding any notation of
ownership or other writing hereon made by anyone), for the purpose of any
exercise hereof, of any distribution to the holder(s) hereof, and for all other
purposes, and the Company shall not be affected by any notice to the contrary.
Neither the Warrants nor this Warrant Certificate entitles any holder hereof to
any rights of a stockholder of the Company.

        This Warrant Certificate shall not be valid unless countersigned by the
Company, as such term is used in the Warrant Agreement.

                           [Signature Page to Follow]

                                      B-3
<PAGE>   40

        IN WITNESS WHEREOF, the Company has caused this Warrant certificate to
be signed by its President and by its Secretary and has caused its corporate
seal to be affixed hereunto or imprinted hereon.

                                     KOMAG, INCORPORATED,
                                     a Delaware corporation

                                     -------------------------------------------
                                     Name:
                                     Title:

                                      B-4
<PAGE>   41

                               [Form of Election]

                    (To Be Executed Upon Exercise of Warrant)

        The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to receive _________ shares of Common
Stock and herewith tenders payment for such shares to the order of Komag,
Incorporated in the amount of $________ as follows: (check applicable box)

        [ ]   in the form of cash or in immediately available funds payable to
              the order of the Company

       *[ ]   in lieu of cash, net shares of Common Stock calculated as
              follows:

              Current Market Price - Exercise Price
              --------------------------------------  x Warrant Shares Exercised
                       Current Market Price

        The undersigned requests that a certificate for such shares be
registered in the name of ________________, whose address is
____________________________ and that such shares be delivered to
________________ whose address is ________________________. If said number of
shares is less than all of the shares of Common Stock purchasable hereunder, the
undersigned requests that a new Warrant Certificate representing the remaining
balance of such shares be registered in the name of _____________, whose address
is ___________________________, and that such Warrant Certificate be delivered
to _________________, whose address is ___________________.

                                      Signature: _______________________________

Date: ________________

                                      Signature Guaranteed: ____________________

* Please note that this is the only form of payment available if this Warrant
Certificate is to be exercised within two years of its issuance.

                                      B-5
<PAGE>   42

                                       B-6
<PAGE>   43

                              [Form of Assignment]

                   (To Be Executed Upon Assignment of Warrant)

        If you, the holder, want to assign this Warrant, fill in the form below
and have your signature guaranteed:

        For value received, I or we assign and transfer this Warrant to:

--------------------------------------------------------------------------------
                      (INSERT ASSIGNEE'S SOCIAL SECURITY OR
                           TAX IDENTIFICATION NUMBER)

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

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

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

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

--------------------------------------------------------------------------------
              (Print or type assignee's name, address and zip code)

and appoints ______________________________________________________ agent to
transfer this security on the books of the Company. The agent may substitute
another to act for him.

        In connection with the transfer of this Warrant, the undersigned
        certifies that:

        (Check one)

           [ ] This Warrant is being transferred to Komag, Incorporated.

           [ ] This Warrant is being transferred to a person or entity other
               than Komag, Incorporated, in connection with which the Company
               has received an opinion of counsel (satisfactory to it in form
               and substance) to the effect that the transfer is being made
               pursuant to an exemption from, or in a transaction not subject
               to, the registration requirements of the Securities Act.

Date: __________________________________________________________________________

Your signature: ________________________________________________________________
                (Sign exactly as your name appears on this Warrant)

Signature Guaranteed by *: _____________________________________________________

* Signature must be guaranteed by an eligible guarantor institution within the
meaning of Securities and Exchange Commission Rule 17Ad-15 (including banks,
stock brokers, savings and loan associations, national securities exchanges,
registered securities associations, clearing agencies and credit unions) with
membership or participation in the Securities Transfer Agents Medallion Program
("STAMP") or such other signature guarantee medallion program as may be approved
by the Registrar in addition to, or substitution for, STAMP, if this Security is
to be delivered other than to and in the name of the registered holder.

IF NONE OF THE FOREGOING BOXES IS CHECKED, THE TRUSTEE SHALL NOT BE OBLIGATED TO
REGISTER THE TRANSFER OF THIS SECURITY UNLESS AND UNTIL THE CONDITIONS TO ANY
SUCH TRANSFER OF REGISTRATION SET FORTH HEREIN, ON THE FACE HEREOF AND IN THE
WARRANT AGREEMENT SHALL HAVE BEEN SATISFIED.

                                      B-7
<PAGE>   44

                                       B-8<PAGE>   1

                                                                     EXHIBIT 4.2

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

                          REGISTRATION RIGHTS AGREEMENT

                                 BY AND BETWEEN

                               KOMAG, INCORPORATED

                                       AND

                               FLEET NATIONAL BANK
                             F/K/A BANKBOSTON, N.A.

                                BANK OF MONTREAL

                            BEAR, STEARNS & CO. INC.

                           COMERICA BANK - CALIFORNIA

                            OLYMPUS SECURITIES, LTD.

                               NELSON PARTNERS LTD

                             THE BANK OF NOVA SCOTIA

                         UNION BANK OF CALIFORNIA, N.A.

                            LOEB PARTNERS CORPORATION

                        THE DAI-ICHI KANGYO BANK, LIMITED

           THE INDUSTRIAL BANK OF JAPAN, LIMITED, SAN FRANCISCO AGENCY

                  THE MITSUBISHI TRUST AND BANKING CORPORATION

                              SANWA BANK CALIFORNIA

                       THE FIRST NATIONAL BANK OF CHICAGO

                             THE FUJI BANK, LIMITED

                           THE SUMITOMO BANK, LIMITED

                            DATED AS OF MAY 25, 2000

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

<PAGE>   2
                                TABLE OF CONTENTS

<TABLE>
<S>          <C>                                                            <C>
SECTION 1.   Definitions ............................................       1

SECTION 2.   Securities Subject to this Agreement ...................       2

              (a) Registrable Securities ............................       2
              (b) Holders of Registrable Securities .................       2

SECTION 3.   Piggyback Registrations ................................       3

              (a) Piggyback Registration ............................       3
              (b) Demand Registrations...............................       4

SECTION 4.   Registration Procedures ................................       5

SECTION 5.   Registration Expenses ..................................      10

SECTION 6.   Indemnification ........................................      11

              (a) Indemnification by Company ........................      11
              (b) Indemnification by Holder of Registrable Securities      12
              (c) Contribution ......................................      13

SECTION 7.   Rule 144 ...............................................      13

SECTION 8.   Participation in Underwritten Registrations ............      14

SECTION 9.   Miscellaneous ..........................................      14

              (a) Termination .......................................      14
              (b) No Inconsistent Agreements ........................      14
              (c) Adjustments Affecting Registrable Securities ......      14
              (d) Amendments and Waivers ............................      14
              (e) Notices ...........................................      15
              (f) Successors and Assigns ............................      15
              (g) Counterparts ......................................      16
              (h) Headings ..........................................      16
              (i) Governing Law .....................................      16
              (j) Severability ......................................      16
              (k) Entire Agreement ..................................      16
</TABLE>

----------
       This Table of Contents does not constitute a part of this Agreement or
       have any bearing upon the interpretation of any of its terms or
       provisions.

                                        i
<PAGE>   3

       THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is dated as of May
25, 2000, and entered into by and between Komag, Incorporated, a Delaware
corporation (the "Company"), and Fleet National Bank f/k/a BankBoston, N.A.,
Bank of Montreal, Bear Stearns & Co., Inc., Comerica Bank - California, Olympus
Securities, Ltd., Nelson Partners, Ltd., The Bank of Nova Scotia, Union Bank of
California, N.A., Loeb Partners Corporation, The Dai-Ichi Kangyo Bank, Limited,
The Industrial Bank of Japan, Limited, San Francisco Agency, The Mitsubishi
Trust and Banking Corporation, Sanwa Bank California, The First National Bank of
Chicago, The Fuji Bank, Limited, and The Sumitomo Bank, Limited (collectively,
"Banks").

       This Agreement is made pursuant to the Warrant Agreement dated as of the
date hereof, between the Company and Banks (the "Warrant Agreement"). To induce
Banks to enter into the Warrant Agreement, the Company has agreed to provide the
registration rights set forth in this Agreement.

       The parties hereby agree as follows:

       SECTION 1. Definitions.

       As used in this Agreement, the following capitalized terms shall have the
following meanings:

       Agent: Any Person authorized to act and who acts on behalf of a Bank with
respect to the transactions contemplated by this Agreement.

       Common Stock: The common stock, $0.01 par value per share, of the
Company.

       Exchange Act: The Securities Exchange Act of 1934, as amended from time
to time.

       NASD: National Association of Securities Dealers, Inc.

       Person: An individual, partnership, corporation, limited liability
company, trust or unincorporated organization, or other business entity, or a
government or agency or political subdivision thereof.

       Prospectus: The prospectus included in any Registration Statement, as
amended or supplemented by any prospectus supplement with respect to the terms
of the offering of any portion of the Registrable Securities covered by the
Registration Statement and by all other amendments and supplements to the
prospectus, including post-effective amendments and all material incorporated by
reference in such prospectus.

       Registrable Securities: The Warrant Shares. Registrable Securities shall
also include any securities which may be issued or distributed with respect to,
or in exchange for, such Registrable Securities pursuant to a stock dividend,
stock split or other distribution, merger, consolidation, recapitalization or
reclassification or similar transaction; provided, however, that any such
Registrable Securities shall cease to be Registrable Securities to the extent
(i) a Registration Statement with respect to the sale of such Registrable
Securities has been declared

                                       1
<PAGE>   4

effective under the Securities Act and such Registrable Securities have been
disposed of in accordance with the plan of distribution set forth in such
Registration Statement, (ii) such Registrable Securities are distributed
pursuant to Rule 144 (or any similar provision then in force) under the
Securities Act, or (iii) such Registrable Securities shall have been otherwise
transferred, new certificates for them not bearing a legend restricting transfer
under the Securities Act shall have been delivered by the Company and they may
be publicly resold without subsequent registration under the Securities Act or
in compliance with Rule 144 thereunder; provided, further, however, that any
securities that have ceased to be Registrable Securities cannot thereafter
become Registrable Securities, and any securities that are issued or distributed
in respect of securities that have ceased to be Registrable Securities are not
Registrable Securities.

       Registration: A Piggyback Registration (as defined in Section 3(a)) or
Demand Registration (as defined in Section 3(b)) of the Company's securities for
sale to the public under a Registration Statement.

       Registration Expenses: See Section 6 hereof.

       Registration Statement: Any registration statement of the Company filed
with the Securities and Exchange Commission under the rules and regulations
promulgated under the Securities Act, including the Prospectus, amendments and
supplements to such Registration Statement, including post-effective amendments,
and all exhibits and all material incorporated by reference in such Registration
Statement.

       Securities Act: The Securities Act of 1933, as amended from time to time.

       SEC: The Securities and Exchange Commission.

       Underwritten Registration or Underwritten Offering: A Registration in
which securities of the Company are sold to an underwriter for reoffering to the
public.

       Warrants: The Series A Common Stock Purchase Warrants and the Series B
Common Stock Purchase Warrants both to purchase shares of Common Stock, issued
and sold pursuant to the Warrant Agreement.

       Warrant Shares: Any shares of Common Stock issued or issuable upon
exercise of any of the Warrants.

       SECTION 2. Securities Subject to this Agreement.

              (a) Registrable Securities. The securities entitled to the
benefits of this Agreement are the Registrable Securities.

              (b) Holders of Registrable Securities. Subject to Section 10(f), a
Person is deemed to be a holder of Registrable Securities whenever such Person
owns Registrable Securities or the Warrants.

                                       2
<PAGE>   5

       SECTION 3. Registrations.

              (a) Piggyback Registrations.

                     (1) Participation. Subject to Section 3(a)(2) hereof, if at
       any time from and after the date hereof the Company proposes to file a
       Registration Statement under the Securities Act with respect to any
       offering of any of its securities of the same class as the Registrable
       Securities, whether or not by the Company for its own account (other than
       (i) a registration on Form S-4 or S-8 or any successor form to such
       Forms, or (ii) any registration of securities as it relates to an
       offering and sale by any employee stock plan or other employee benefit
       plan arrangement), then, as promptly as practicable, the Company shall
       give written notice of such proposed filing to each holder of Registrable
       Securities and such notice shall offer the holders of Registrable
       Securities the opportunity to register such number of Registrable
       Securities as each such holder may request (a "Piggyback Registration").
       Subject to Section 3(b), the Company shall include in such Registration
       Statement all Registrable Securities requested within 30 days after the
       receipt of any such notice (which request shall specify the Registrable
       Securities intended to be disposed of by such holder) to be included in
       the Registration for such offering pursuant to a Piggyback Registration.
       Each holder of Registrable Securities shall be permitted to withdraw all
       or part of such holder's Registrable Securities from a Piggyback
       Registration at any time prior to the earlier of the effective date or
       any request for the acceleration of the effective date thereof. The
       Company shall keep any Registration Statement filed pursuant to this
       Section 3(a)(1) current and effective for a period expiring on the
       earlier of six months from the effective date of such Registration
       Statement or until all of the Registrable Securities registered pursuant
       to this Section 3(a) have been sold. Notwithstanding the foregoing, in
       the event that, in the good faith judgment of the Company's Board of
       Directors, it is advisable to suspend use of the Prospectus due to
       impending corporate developments, public filings with the SEC or similar
       events, the Company shall deliver promptly a written certificate to each
       holder of Registrable Securities and the managing underwriters, if any,
       to the effect that the use of the Prospectus is to be suspended until the
       Company shall deliver a written notice that the use of the Prospectus may
       be resumed. Thereafter, the use of the Prospectus shall be suspended, and
       the Company shall not be required to maintain the effectiveness of, or
       amend or update the Registration Statement, or amend or supplement the
       Prospectus; provided, however, that the Company shall only be permitted
       to suspend the use of the Prospectus for a period not to exceed 45 days
       in any six-month period or two periods not to exceed an aggregate of 90
       days in any 12-month period. The Company will use its best efforts to
       ensure that the use of the Prospectus may be resumed as soon as, in the
       good faith judgment of the Company's Board of Directors, disclosure of
       the material relating to such pending development, filing or event would
       not have a materially adverse effect on the Company. If the Company shall
       give any suspension notice pursuant to this Section 3(a)(1), the period
       contemplated by Section 4(b) hereof shall be extended by the number of
       days during such period from and including the date of giving notice to
       and including the date of giving such notice to and including the date
       when each holder of

                                       3
<PAGE>   6

       Registrable Securities shall have received notice that the use of the
       Prospectus may be resumed.

                     (2) Underwriter's Cutback. The Company shall use its best
       efforts to cause the managing underwriter or underwriters of a proposed
       Underwritten Offering to permit the Registrable Securities requested to
       be included in the Registration for such offering under Section 3(a)(1)
       (the "Piggyback Securities"), to be included on the same terms and
       conditions as any similar securities included therein. Notwithstanding
       the foregoing, if the managing underwriter of any such proposed
       Underwritten Offering determines that marketing factors require a
       limitation of the number of securities to be underwritten, the managing
       underwriter may limit or exclude the amount of Registrable Securities to
       be included in the registration and underwriting as follows: the Company
       will include in such registration (i) first, all of the securities the
       Company proposes to sell and (ii) second, the Piggyback Securities and
       other securities sought to be registered, on a pro rata basis, based upon
       the number of securities sought to be registered by the holders of the
       Piggyback Securities and the holders of the other securities sought to be
       registered. If the managing underwriter makes such a determination, the
       Company shall promptly advise the holders of the Registrable Securities,
       in writing, that a limitation or inclusion of fewer than all of the
       Piggyback Securities is likely. If a reduction in the total amount of
       securities to be included in such offering is necessary as described in
       the prior sentence, the Company shall not treat the holders of the
       Piggyback Securities less favorably than directors, officers, controlling
       stockholders and their affiliates seeking piggyback registration rights.

       (b)    Demand Registrations.

                     (1) Obligation to File. At any time following the issuance
       of Warrants pursuant to the Warrant Agreement, promptly upon the written
       request of holders of a majority of the then outstanding Registrable
       Securities, the Company will use its reasonable best efforts to file with
       the SEC a Registration Statement under the Securities Act for the
       offering of all of the Registrable Securities which such holders request
       to be registered (the "Demand Registration"), provided, that the number
       of Registrable Securities to be registered (i) are not less than 200,000
       or (ii) if less than 200,000, constitutes all of the remaining
       Registrable Securities. The Demand Registration shall be on an
       appropriate form and the Demand Registration and any form of prospectus
       included therein shall reflect such plan of distribution or method of
       sale as such holders notify the Company, including the sale of some or
       all of the Registrable Securities in a public offering. The Company shall
       use its reasonable best efforts to cause the Demand Registration to
       become effective, and, upon the request of any of such holders, keep the
       Demand Registration effective for up to 60 days, unless the distribution
       of securities registered thereunder has been earlier completed. During
       the period during which the Demand Registration is effective, the Company
       shall supplement or make amendments to the Demand Registration, if
       required by the Securities Act, including to reflect any specific plan of
       distribution or method of sale, and shall use its reasonable best efforts
       to have such supplements and amendments declared effective, if required,
       as soon as practicable after filing. Notwithstanding the foregoing, the

                                        4
<PAGE>   7

       Company shall have the right to delay any Demand Registration for a
       period of not more than 90 days after the date of any request to register
       the Registrable Securities pursuant to the Demand Registration, if, at
       the time of such request, the Company is preparing, or within ten days
       thereafter engages an underwriter, and commences in good faith to
       prepare, a Registration Statement for a public offering (other than a
       registration relating solely to employee benefit plans) which is in fact
       filed and becomes effective within 90 days after the date the holders of
       the Registrable Securities have provided the written registration
       request, or is engaged in any material acquisition or divestiture or
       other business transaction with a third party which the Board of
       Directors of the Company reasonably determines in good faith would be
       adversely affected by the Demand Registration to the material detriment
       of the Company.

                     (2) Number of Demand Registrations. The Company shall be
       obligated to effect, under this Section 3(b), (i) not more than two
       Demand Registrations during any 12 month period covering Registrable
       Securities issued or issuable within the two year period prior to the
       request for such Demand Registration, and (ii) not more than one Demand
       Registration during any 12 month period covering Registrable Securities
       issued more than two years before the request for such Demand
       Registration in the event that Rule 144 of the Securities Act does not
       permit such Registrable Securities to be freely tradeable by the
       purchasers thereof, provided, however, that, in any event, the Company
       shall not be obligated to effect more than one Demand Registration during
       the 12 month period after the Company files a Registration Statement on
       which holders of Registrable Securities that so elect are permitted to
       include as many Piggyback Securities as such holder desires without any
       reduction in the amount of such Piggyback Securities pursuant to
       paragraph 3(a)(2) hereof. A Demand Registration shall not be deemed to
       have been effected, nor shall it be sufficient to reduce the number of
       Demand Registrations available to the holders of Registrable Securities
       requesting a Demand Registration under this Section 3(b), if such
       registration cannot be used by holders of Registrable Securities for more
       than 120 days as a result of any stop order, injunction or other order of
       the SEC or other government authority for any reason other than an act or
       omission of such holders and all the Registrable Securities registered
       thereunder are not sold.

                     (3) Selection of Underwriters. Any and all underwriters or
       other agents involved in any sale of Registrable Securities pursuant to a
       Registration Statement contemplated by this Section 3(b) shall include
       such underwriter(s) or other agent(s) as selected by the holders of a
       majority of Registrable Securities being registered and approved of by
       the Company, which approval shall not be unreasonably withheld; provided
       that any affiliate of a holder requesting a Demand Registration shall in
       all events be approved by the Company.

       SECTION 4. Registration Procedures.

       In connection with the Company's registration obligations pursuant to
Section 3 hereof, the Company will use its commercially reasonable efforts to
effect such registration to permit the sale

                                        5
<PAGE>   8

of such Registrable Securities in accordance with the intended methods or
methods of disposition thereof, and pursuant thereto the Company will as
expeditiously as possible:

              (a) before filing a Registration Statement or Prospectus or any
amendments or supplements thereto, furnish to the holders of the Registrable
Securities covered by such Registration Statement and the underwriters, if any,
copies of all such documents proposed to be filed, which documents will be
subject to the review of such holders and underwriters, and the Company will not
file any Registration Statement or amendment thereto or any Prospectus or any
supplement thereto to which the holders of a majority of the Registrable
Securities covered by such Registration Statement or the underwriters, if any,
shall reasonably object within three days after such documents are delivered;

              (b) prepare and file with the SEC a Registration Statement or
Registration Statements relating to the applicable Demand Registration or
Piggyback Registration including all exhibits and financial statements required
by the SEC to be filed therewith, and use its commercially reasonable efforts to
cause such Registration Statement to become effective under the Securities Act;
and prepare and file with the SEC such amendments and post-effective amendments
to such Registration Statement, and such supplements to the Prospectus, as may
be required by the rules, regulations or instructions applicable to the
registration form utilized by the Company or by the Securities Act or rules and
regulations otherwise necessary to keep the Registration Statement effective for
a period of not less than 180 days (or such shorter period which will terminate
when all Registrable Securities covered by such Registration Statement have been
sold or withdrawn), or, if such Registration Statement relates to an
Underwritten Offering, such longer period as in the opinion of counsel for the
underwriters a Prospectus is required by law to be delivered in connection with
sales of Registrable Securities by an underwriter or dealer; and cause the
Prospectus as so supplemented to be filed pursuant to Rule 424 under the
Securities Act; and comply with the provisions of the Securities Act and the
Exchange Act with respect to the disposition of all securities covered by such
Registration Statement during the applicable period in accordance with the
intended methods of disposition by the sellers thereof set forth in such
Registration Statement or supplement to the Prospectus;

              (c) notify the selling holders of Registrable Securities and the
managing underwriters, if any, promptly;

                     (1) when the Prospectus or any Prospectus supplement or
posteffective amendment has been filed, and, with respect to the Registration
Statement or any post-effective amendment, when the same has become effective,

                     (2) of any request by the SEC during the period of
              effectiveness for amendments or supplements to the Registration
Statement or the Prospectus or for additional information relating to the
Registration Statement,

                     (3) of the issuance by the Commission of any stop order
suspending the effectiveness of the Registration Statement or the initiation of
any proceedings for that purpose,

                                        6
<PAGE>   9

                     (4) if at any time the representations and warranties of
the Company contemplated by paragraph (n) below cease to be true and correct,

                     (5) of the receipt by the Company of any notification with
respect to the suspension of the qualification of the Registrable Securities for
sale in any jurisdiction or the initiation or threatening of any proceeding for
such purpose, and

                     (6) of the existence of any fact known which results in the
Registration Statement, the Prospectus or any document incorporated therein by
reference containing an untrue statement of material fact or omitting to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading;

              (d) make every reasonable effort to obtain the withdrawal of any
order suspending the effectiveness of the Registration Statement at the earliest
possible moment;

              (e) if requested by the managing underwriter or underwriters or a
holder of Registrable Securities being sold in connection with an Underwritten
Offering, immediately incorporate in a Prospectus supplement or post-effective
amendment such information as the managing underwriters and the holders of a
majority of the Registrable Securities being sold require to be included therein
relating to the plan of distribution with respect to such Registrable
Securities, including, without limitation, information with respect to the
amount of Registrable Securities being sold to such underwriters, the purchase
price being paid therefor by such underwriters and with respect to any other
terms of the underwritten (or best efforts underwritten) offering of the
Registrable Securities to be sold in such offering; and make all required
filings of such Prospectus supplement or post-effective amendment as soon as
notified of the matters to be incorporated in such Prospectus supplement or
post-effective amendment;

              (f) deliver to each selling holder of Registrable Securities and
the underwriters, if any, without charge, as many copies of the Prospectus
(including each preliminary prospectus) and any amendment or supplement thereto
as such Persons may reasonably request (it being understood that the Company
consents to the use of the Prospectus or any amendment or supplement thereto by
each of the selling holders of Registrable Securities and the underwriters, if
any, in connection with the offering and sale of the Registrable Securities
covered by the Prospectus or any amendment or supplement thereto) and such other
documents as such selling holder and the underwriters, if any, may reasonably
request in order to facilitate the disposition of the Registrable Securities by
such holder and underwriters, if any, but only while the Company shall be
required under the provisions hereof to cause the Registration Statement to
remain current;

              (g) prior to any public offering of Registrable Securities, use
its commercially reasonable efforts to register or qualify or cooperate with the
selling holders of Registrable Securities, the underwriters, if any, and their
respective counsel in connection with the registration or qualification of such
Registrable Securities for offer and sale under the securities or blue sky laws
of such jurisdictions as any selling holder of Registrable Securities or any
underwriter reasonably requests in writing and do any and all other acts or
things reasonably

                                        7
<PAGE>   10

necessary to enable the disposition in such jurisdictions of the Registrable
Securities covered by the Registration Statement; provided that the Company will
not be required to qualify generally to do business in any jurisdiction where it
is not then so qualified or to take any action which would subject it to general
service of process in any such jurisdiction where it is not then so subject;

              (h) cooperate with the selling holders of Registrable Securities
and the managing underwriters, if any, to facilitate the timely preparation and
delivery of certificates representing Registrable Securities to be sold and not
bearing any restrictive legends; and enable such Registrable Securities to be in
such denominations and registered in such names as the managing underwriters may
request at least two business days prior to any sale of Registrable Securities
to the underwriters;

              (i) use its commercially reasonable efforts to cause the
Registrable Securities covered by the applicable Registration Statement to be
registered with or approved by such other governmental agencies or authorities
within the U.S. as may be necessary to enable the seller or sellers thereof or
the underwriters, if any, to consummate the disposition of such Registrable
Securities; provided that the Company will not be required to qualify generally
to do business in any jurisdiction where it is not then so qualified or to take
any action which would subject it to general service of process in any such
jurisdiction where it is not then so subject;

              (j) if any fact contemplated by paragraph (c)(6) above shall
exist, prepare a supplement or post-effective amendment to the Registration
Statement or the related Prospectus or any document incorporated therein by
reference or file any other required document so that, as thereafter delivered
to the purchasers of the Registrable Securities, the Prospectus will not contain
an untrue statement of a material fact or omit to state any material fact
required to be stated therein or necessary to make the statements therein not
misleading, but only while the Company shall be required under the provisions
hereof to cause the Registration Statement to remain current;

              (k) use its commercially reasonable efforts to cause all
Registrable Securities covered by the Registration Statement to be quoted on the
NASDAQ National Market or listed on each securities exchange on which similar
securities issued by the Company are then listed;

              (l) enter into agreements (including underwriting agreements) and
take all other appropriate actions that are reasonable, necessary and in typical
form for such transactions in order to expedite or facilitate the disposition of
such Registrable Securities.

The above shall be done at the effectiveness of such Registration Statement,
each closing under any underwriting or similar agreement as and to the extent
required thereunder and from time to time as may be requested by any selling
holder in connection with the disposition of Registrable Securities pursuant to
such Registration Statement, but only while the Company shall be required under
the provisions hereof to cause the Registration Statement to remain current;

                                        8
<PAGE>   11

              (m) make available for inspection at reasonable times and upon
reasonable notice by a representative of the holders of a majority of the
Registrable Securities, any underwriter participating in any disposition
pursuant to such Registration Statement, and any attorney or accountant retained
by the sellers or underwriter, all financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, directors and employees to supply all information reasonably requested
by any such representative, underwriter, attorney or accountant in connection
with the registration; provided that any records, information or documents that
are designated by the Company in writing as confidential shall be kept
confidential by such Persons unless disclosure of such records, information or
documents is required by court or administrative order; and

              (n) otherwise use its commercially reasonable efforts to comply
with all applicable rules and regulations of the SEC, and make generally
available to its security holders, earnings statements satisfying the provisions
of Section 11(a) of the Securities Act, no later than 45 days after the end of
any fiscal quarter (or 90 days after the end of any fiscal year) (1) commencing
at the end of any fiscal quarter in which Registrable Securities are sold to
underwriters in an Underwritten Offering, or, if not sold to underwriters in
such an offering, (2) beginning with the first month of the Company's first
fiscal quarter commencing after the effective date of the Registration
Statement, which statements shall cover said 12-month periods

              The Company may require each seller of Registrable Securities as
to which any registration is being effected to furnish to the Company such
information regarding itself, the Registrable Securities held by it and the
distribution of such securities as the Company may from time to time reasonably
request in writing, and shall take such commercially reasonable action as may be
reasonably required in order to permit the Company and any underwriters to
comply with all applicable requirements of the SEC and the NASD. Such provision
of information and materials is a condition precedent to the obligations of the
Company pursuant to this Agreement.

              Each holder of Registrable Securities agrees by acquisition of
such Registrable Securities that, upon receipt of any notice from the Company of
the happening of any event of the kind described in Sections 4(c)(3), 4(c)(4),
4(c)(5), 4(c)(6) or 4(j) hereof, such holder will forthwith discontinue
disposition of Registrable Securities until such holder's receipt of the copies
of the supplemented or amended Prospectus contemplate by Sections 4(c)(3),
4(c)(4), 4(c)(5), 4(c)(6) or 4(j) hereof, or until it is advised in writing by
the Company that the use of the Prospectus may be resumed, and has received
copies of any additional or supplemental filings which are incorporated by
reference in the Prospectus, and, if so directed by the Company, such holder
will deliver to the Company (at the Company's expense) all copies, other than
permanent file copies then in such holder's possession, of the Prospectus
covering such Registrable Securities current at the time of receipt of such
notice. In the event the Company shall give any such notice, the time periods
during which such Registration Statement shall be maintained effective shall be
extended by the number of days during the period from and including the date of
the giving of such notice to and including the date when each seller of
Registrable Securities covered by such Registration Statement either receives
the copies of the supplemented or

                                        9
<PAGE>   12

amended prospectus contemplated by Sections 4(c)(3), 4(c)(4), 4(c)(5), 4(c)(6)
or 4(j) hereof or is advised in writing by the Company that the use of the
Prospectus may be resumed.

       SECTION 5. Registration Expenses.

              (a) All expenses incident to the Company's performance of or
compliance with this Agreement will be paid by the Company, regardless of
whether the Registration Statement becomes effective, including without
limitation:

                     (1) all registration and filing fees (including all filings
       required to be made with the SEC and the NASD;

                     (2) fees and expenses of compliance with securities or blue
       sky laws (including fees and disbursements of counsel for the
       underwriters or selling holders in connection with blue sky
       qualifications of the Registrable Securities and determination of their
       eligibility for investment under the laws of such jurisdictions as the
       managing underwriters or holders of a majority of the Registrable
       Securities being sold may designate);

                     (3) printing (including expenses of printing certificates
       for the Registrable Securities in a form eligible for deposit with the
       Depository Trust Company and of printing prospectus), messenger,
       telephone and delivery expenses;

                     (4) fees and disbursements of counsel for the (i) Company,
       (ii) the underwriters and (iii) the sellers of the Registrable Securities
       (subject to the provisions of Section 6(b) hereof);

                     (5) fees and disbursements of all independent certified
       public accountants of the Company (including the expenses of any special
       audit and "cold comfort" letters required by or incident to such
       performance);

                     (6) fees and disbursements of underwriters (including, if
       applicable, the fees and expenses of any "qualified independent
       underwriter" (and its counsel) that is required to be retained in
       accordance with the rules and regulations of the NASD, but excluding
       discounts, commissions or fees of underwriters, selling brokers, dealer
       managers or similar securities industry professionals relating to the
       distribution of the Registrable Securities or legal expenses of any
       Person other than the Company, the underwriters and the selling holders);

                     (7) securities acts liability insurance if the Company so
       desires or if the underwriters or selling holders of a majority of the
       Registrable Securities so require; and

                     (8) fees and expenses of other Persons retained by the
       Company,

(all such expenses being herein called "Registration Expenses").

                                       10
<PAGE>   13

              The Company will, in any event, pay its internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees performing legal or accounting duties), the expense of any annual
audit, the fees and expenses incurred in connection with the listing of the
securities to be registered on each securities exchange on which similar
securities issued by the Company are then listed, rating agency fees and the
fees and expenses of any Person, including special experts, retained by the
Company.

              (b) In connection with each Registration Statement required
hereunder, the Company will reimburse the holders of Registrable Securities
being registered pursuant to such Registration Statement for the reasonable fees
and disbursements of not more than one counsel chosen by the holders of a
majority of such Registrable Securities.

       SECTION 6. Indemnification.

              (a) Indemnification by Company. The Company agrees to indemnify
and hold harmless each holder of Registrable Securities, its officers,
directors, employees and Agents and each Person who controls such holder within
the meaning of either Section 15 of the Securities Act or Section 20 of the
Exchange Act (each such person being sometimes hereinafter referred to as an
"Indemnified Holder") from and against all losses, claims, damages, liabilities
and expenses (including reasonable costs of investigation and legal expenses)
arising out of or based upon any untrue statement or alleged untrue statement of
a material fact contained in any Registration Statement or Prospectus, in any
amendment or supplement thereto or in any preliminary prospectus, or arising out
of or based upon any omission or alleged omission to state therein a material
fact required to be stated therein or necessary to make the statements therein
not misleading, except insofar as such losses, claims, damages, liabilities or
expenses arises out of or are based upon any such untrue statement or omission
or allegation thereof based upon information furnished in writing to the Company
by or on behalf of such holder expressly for use therein; provided, however,
that the Company shall not be liable in any such case to the extent that any
such loss, claim, damage, liability or expense arises out of or is based upon an
untrue statement or alleged untrue statement or omission or alleged omission in
any such Registration Statement or Prospectus or preliminary prospectus, if such
untrue statement or alleged untrue statement, omission or alleged omission is
completely corrected in an amendment or supplement to such Registration
Statement or Prospectus or preliminary prospectus and if, having previously been
furnished by or on behalf of the Company with copies of the Prospectus or
preliminary prospectus as so amended or supplemented, such holder thereafter
fails to deliver such Prospectus or preliminary prospectus as so amended or
supplemented, prior to or concurrently with the sale of a Registrable Security
to the Person asserting such loss, claim, damage, liability or expense who
purchased such Registrable Security which is the subject thereof from such
holder. The indemnity will be in addition to any liability which the Company may
otherwise have. The Company will also indemnify underwriters, selling brokers,
dealer managers and similar securities industry professionals participating in
the distribution, their officers and directors and each Person who controls such
Persons (within the meaning of Section 15 of the Securities Act or Section 20 of
the Exchange Act) to the same extent as provided above with respect to the
indemnification of the Indemnified Holders of Registrable Securities.

                                       11
<PAGE>   14

              If any action or proceeding (including any governmental
investigation or inquiry) shall be brought or asserted against an Indemnified
Holder in respect of which indemnity may be sought from the Company, such
Indemnified Holder shall promptly notify the Company in writing, and the Company
shall assume the defense thereof, including the employment of counsel
satisfactory to such Indemnified Holder and the payment of all expenses. Such
Indemnified Holder shall have the right to employ separate counsel in any such
action and to participate in the defense thereof, but the fees and expenses of
such counsel shall be at the expense of such Indemnified Holder unless (a) the
Company has agreed to pay such fees and expenses or (b) the Company shall have
failed to assume the defense of such action or proceeding and has failed to
employ counsel reasonably satisfactory to such Indemnified Holder in any such
action or proceeding (including any impleaded parties) include both such
Indemnified Holder and the Company or (c) such Indemnified Holder shall have
been advised in writing by counsel that there is a conflict of interest between
such Indemnified Holder and the Company or that there are additional defenses or
claims that it may assert that are adverse to or not in the interest of the
Company and separate counsel is required to represent such interests (in which
case, if such Indemnified Holder notifies the Company in writing that it elects
to employ separate counsel at the expense of the Company, the Company shall not
have the right to assume the defense of such action or proceeding on behalf of
such Indemnified Holder, it being understood, however, that the Company shall
not, in connection with any one such action or proceeding or separate but
substantially similar or related actions or proceedings in the same jurisdiction
arising out of the same general allegations or circumstances, be liable for the
reasonable fees and expenses of more than one separate firm of attorneys at any
time for such Indemnified Holder and any other Indemnified Holders, which firm
shall be designated in writing by such Indemnified Holders). The Company shall
not be liable for any settlement of any such action or proceeding effected
without its written consent, but if settled with its written consent, or if
there be a final judgment for the plaintiff in any such action or proceeding for
which the Company received notice hereunder, the Company agrees to indemnify and
hold harmless such Indemnified Holder from and against any loss or liability by
reason of such settlement or judgment.

              (b) Indemnification by Holder of Registrable Securities. Each
holder of Registrable Securities agrees to indemnify and holder harmless the
Company, its directors and officers and each Person, if any, who controls the
Company within the meaning of either Section 15 of the Securities Act or Section
20 of the Exchange Act to the same extent as the foregoing indemnity from the
Company to such holder, but only with respect to information relating to such
holder furnished in writing by such holder expressly for use in any Registration
Statement or Prospectus, or any amendment thereto, or any preliminary
prospectus. In case any action or proceeding shall be brought against the
Company or directors or officers or any such controlling person, in respect of
which indemnity may be sought against a holder of Registrable Securities, such
holder shall have the rights and duties given the Company and the Company or its
directors or officers or such controlling person shall have the rights and
duties given to each holder by the preceding paragraph. In no event shall the
liability of any selling holder of Registrable Securities hereunder be greater
in amount than the gross amount of the proceeds (before expenses and
commissions) from the sale of Registrable Securities by such holder giving rise
to such indemnification obligation.

                                       12
<PAGE>   15

              The Company and each holder of Registrable Securities shall be
entitled to receive indemnities from underwriters, selling brokers, dealer
managers and similar securities industry professionals participating in the
distribution, to the same extent as provided above with respect to information
so furnished in writing by such Person specifically for inclusion in any
Prospectus or Registration Statement or any amendment or supplement thereto, or
any preliminary prospectus.

              (c) Contribution. If the indemnification provided for in this
Section 7 is unavailable to an indemnified party under Section 7(a) or Section
7(b) hereof (other than by reason of exceptions provided in those Sections) in
respect of any losses, claims, damages, liabilities or expenses referred to
therein, then each applicable indemnifying party, in lieu of indemnifying such
indemnified party, shall contribute to the amount paid or payable by such
indemnified party as a result of such losses, claims, damages, liabilities or
expenses in such proportion as is appropriate to reflect the relative fault of
the Company on the one hand and of the Indemnified Holder on the other in
connection with the statements or omissions which resulted in such losses,
claims, damages, liabilities or expenses, as well as any other relevant
equitable considerations. The relative fault of the Company on the one hand and
of the Indemnified Holder on the other shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the Company or by the Indemnified Holder and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission. The amount paid or payable by a
party as a result of the losses, subject to the limitations set forth in the
second paragraph of Section 7(a), any legal or other fees or expenses reasonably
incurred by such party in connection with investigating or defending any action
or claim.

              The Company and each holder of Registrable Securities agree that
it would not be just and equitable if contribution pursuant to this Section 7(c)
were determined by pro rata allocation or by any other method of allocation
which does not take account of the equitable considerations referred to in the
immediately preceding paragraph. Notwithstanding the provisions of this Section
7(c), an Indemnified Holder shall not be required to contribute any amount in
excess of the amount by which the total price at which the Securities sold by
such Indemnified Holder or its affiliated Indemnified Holders and distributed to
the public were offered to the public exceeds the amount of any damages which
such Indemnified Holder or its affiliated Indemnified Holder, has otherwise been
required to pay by reason of such untrue or alleged untrue statement or omission
or alleged omission. No person guilty of fraudulent misrepresentation (within
the meaning of Section 11(f) of the Act) shall be entitled to contribution from
any person who was not guilty of such fraudulent misrepresentation.

       SECTION 7. Rule 144.

       The Company covenants that it will file the reports required to be filed
by it under the Securities Acts and the Exchange Act and rules and regulations
adopted by the SEC thereunder (or, if the Company is not required to file such
reports, it will, upon the request of any holder of Registrable Securities made
after the first anniversary of the date hereof, make publicly available such
information as necessary to permit sales pursuant to Rule 144 under the
Securities Act), and it will take such further action as any holder of
Registrable Securities may reasonably request, all to

                                       13
<PAGE>   16

the extent required from time to time to enable such holder to sell Registrable
Securities without registration under the Securities Act within the limitation
of the exemptions provided by (a) Rule 144 under the Securities Act, as such
Rule may be amended from time to time, or (b) any similar rule or regulation
hereafter adopted by the SEC. Upon the request of any holder of Registrable
Securities, the Company will deliver to such holder a written statement as to
whether it had complied with such information and requirements.

       SECTION 8. Participation in Underwritten Registrations.

              No Person may participate in any Underwritten Registration
hereunder unless such Person (a) agrees to sell such Person's securities on the
basis provided in any underwriting arrangements approved by the Persons entitled
hereunder to approve such arrangements and (b) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents required under the terms of such underwriting arrangements.

       SECTION 9. Miscellaneous.

              (a) Termination. The registration rights set forth in this
Agreement shall terminate (a) at any time, upon mutual agreement in writing of
the Parties hereto or (b) upon such time as all of the Registrable Securities
then held by the parties hereto can be sold by such parties in a three-month
period in accordance with Rule 144 under the Securities Act. Notwithstanding the
foregoing, the obligations of each party to this Agreement pursuant to Section
12 hereof, shall survive the termination of registration rights sets forth in
this Agreement.

              (b) No Inconsistent Agreements. The Company will not on or after
the date of this Agreement enter into any agreement with respect to its
securities which is inconsistent with the rights granted to the holders of
Registrable Securities in this Agreement or otherwise conflicts with the
provisions hereof.

              (c) Adjustments Affecting Registrable Securities. The Company will
not take any action, or permit any change to occur, with respect to the
Registrable Securities which would (i) adversely affect the ability of the
holders of Registrable Securities to include such Registrable Securities in a
registration undertaken pursuant to this Agreement or (ii) adversely affect the
marketability of such Registrable Securities in any such registration.

              (d) Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given without the written consent of the Company and holders of at
least a majority of the outstanding Registrable Securities affected by such
amendment. Notwithstanding the foregoing, a waiver or consent to departure from
the provisions hereof that relates exclusively to the rights of holders of
Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect the
rights of other holders of Registrable Securities may be given by the holders of
a majority of the Registrable Securities being sold.

                                       14
<PAGE>   17

              (e) Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, telex, telecopier, or air courier guaranteeing overnight
delivery:

                     (i) if to a holder of Registrable Securities, at the most
              current address given by such holder to the Company in accordance
              with the provisions of this Section 10(e).

                     With a copy to:

                            Stroock & Stroock & Lavan LLP
                            2029 Century Park East, 16th Floor
                            Los Angeles, California 90067
                            Facsimile: 310-556-5959
                            Attention: Gregory A. Bray, Esq.

                     (ii) if to the Company, initially to:

                            Komag, Incorporated
                            1710 Automation Parkway
                            San Jose, California 95131-1873
                            Facsimile:  408-944-9234
                            Attention: Chief Financial Officer

                     and thereafter at such other address, notice of which is
                     given in accordance with the provisions of this Section
                     10(e),

                     With a copy to:

                            Wilson Sonsini Goodrich & Rosati
                            650 Page Mill Road
                            Palo Alto, California 94304-1050
                            Facsimile: 650-493-6811
                            Attn: Alan K. Austin, Esq.

              All such notices and communications shall be deemed to have been
duly given: at the time delivered by hand, if personally delivered; five
business days after being deposited in the mail, postage prepaid, if mailed;
when answered back, if telexed; when receipt acknowledged, if telecopied; and on
the next business day, if timely delivered to an air courier guaranteeing
overnight delivery.

              (f) Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors and assigns of each of the
parties, including without limitation and without the need for an express
assignment, subsequent permitted holders of Registrable Securities.

                                       15
<PAGE>   18

              (g) Counterparts. This Agreement may be executed in any number of
counterparts and by the parties hereto in separate counterparts, each of which
when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement.

              (h) Headings. The headings in this Agreement are for convenience
of reference only and shall not limit or otherwise affect the meaning hereof.

              (i) Governing Law. This Agreement shall be governed by and
construed in accordance with the laws of the State of California.

              (j) Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

              (k) Entire Agreement. This Agreement is intended by the parties as
a final expression of their agreement and intended to be a complete and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter contained herein. There are no restrictions,
promises, warranties or undertakings, other than those set forth or referred to
herein with respect to the registration rights granted by the Company with
respect to the securities sold pursuant to the Purchase Agreement. This
Agreement supersedes all prior agreements and understandings between the parties
with respect to such subject matter.

                           [Signature Pages To Follow]

                                       16
<PAGE>   19

              IN WITNESS WHEREOF, the parties have executed this Agreement as of
the date first written above.

KOMAG, INCORPORATED

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
1710 Automation Parkway
San Jose, California 95131-1873
Facsimile: (408) 944-9234
Attention:  Chief Financial Officer

FLEET NATIONAL BANK f/k/a BANKBOSTON, N.A.,
as Restructure Agent and as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
100 Federal Street, Mail Stop 01-06-01
Boston, MA 02110
Facsimile:  (617) 434-4775
Attention:  Donald Sheehan

BANK OF MONTREAL, as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
115 S. LaSalle Street, 12 West
Chicago, IL 60603
Facsimile:  (312) 750-6057
Attention:  Jack J. Kane

                                       S-1
<PAGE>   20

BEAR, STEARNS & CO. INC.,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
245 Park Avenue
New York, New York  10167
Facsimile:  (212) 272-8102
Attention:
          -------------------------------------------

COMERICA BANK - CALIFORNIA,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
55 Almaden Boulevard
Mail Code: 4041
San Jose, California  95113
Facsimile: (408) 556-5855
Attention:  Carol A. Palestro

OLYMPUS SECURITIES, LTD.,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
c/o Citadel Investment Group, LLC
225 West Washington Street, 9th Floor
Chicago, Illinois  60606
Facsimile:  (312) 368-4650
Attention:  Bradford Couri

                                       S-2
<PAGE>   21

NELSON PARTNERS LTD.,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
c/o Citadel Investment Group, LLC
225 West Washington Street, 9th Floor
Chicago, Illinois  60606
Facsimile:  (312) 368-4650
Attention:  Bradford Couri

THE BANK OF NOVA SCOTIA,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
One Liberty Plaza
New York, New York 10006
Facsimile:  (212) 225-5205
Attention:  Norm Gillespie

UNION BANK OF CALIFORNIA, N.A.,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
350 California Street, 7th Floor
San Francisco, California  94104
Facsimile:  (415) 705-7390
Attention:  Christiana Creekpaum

                                       S-3
<PAGE>   22

LOEB PARTNERS CORPORATION,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
61 Broadway, 24th Floor
New York, New York  10006
Facsimile:  (212) 574-2003
Attention:  Robert Grubin

THE DAI-ICHI KANGYO BANK, LIMITED,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
Corporate Finance Department I
One World Trade Center, Suite 4911
New York, NY 10048
Facsimile:  (212) 912-1879
Attention:  Nelson Chang

THE INDUSTRIAL BANK OF JAPAN, LIMITED,
SAN FRANCISCO AGENCY,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
555 California Street, Suite 3110
San Francisco, California  94104
Facsimile:  (415) 982-1917
Attention:  Joseph A. Endoso

                                      S-4
<PAGE>   23

THE MITSUBISHI TRUST AND BANKING CORPORATION,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
520 Madison Avenue, 26th Floor
New York, NY 10022
Facsimile:  (212) 644-6825
Attention:  Daniel Chang

SANWA BANK CALIFORNIA,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
444 Market Street, 22nd Floor
San Francisco, CA 94111
Facsimile:  (415) 597-5491
Attention:  George Vetek

THE FIRST NATIONAL BANK OF CHICAGO,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
The First National Bank of Chicago
c/o Bank One
Western Region Managed Assets
AZ1-1283
201 N. Central Avenue
Phoenix, AZ 85004-2267
Facsimile:  (602) 221-1737
Attention:  Dennis Warren

                                      S-5
<PAGE>   24

THE FUJI BANK, LIMITED,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
333 South Hope Street
Los Angeles, CA  90071
Facsimile:  (213) 253-4178
Attention:
          -------------------------------------------

THE SUMITOMO BANK, LIMITED,
as a Restructure Lender

By:
   --------------------------------------------------
Title:
      -----------------------------------------------

Address:
555 California Street, Suite 3350
San Francisco, California  94104
Facsimile:  (415) 398-3580
Attention:  Azar Shakeri

                                       S-6

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