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                                DOUBLECLICK INC.

               ZERO COUPON CONVERTIBLE SUBORDINATED NOTES DUE 2023

                          REGISTRATION RIGHTS AGREEMENT

                                                              New York, New York
                                                                   June 23, 2003

Citigroup Global Markets Inc.
as Representative of the Initial Purchasers Named in
Schedule I to the Purchase Agreement (as defined below)
388 Greenwich Street
New York, New York 10013

Ladies and Gentlemen:

         DoubleClick Inc., a Delaware corporation (the "COMPANY"), proposes to
issue and sell (such issuance and sale, the "INITIAL PLACEMENT") to the several
parties named in Schedule I to the Purchase Agreement (the "INITIAL PURCHASERS")
for whom you (the "REPRESENTATIVE") are acting as the representative, upon the
terms set forth in a purchase agreement dated June 17, 2003 (the "PURCHASE
AGREEMENT"), $135,000,000 aggregate principal amount (plus an option to purchase
up to an additional $20,250,000 aggregate principal amount) of its Zero Coupon
Convertible Subordinated Notes due 2023 (the "SECURITIES"). The Securities will
be convertible into shares of common stock, par value $.001 per share, of the
Company at the conversion rate set forth in the Offering Memorandum (as defined
herein), as the same may be adjusted from time to time pursuant to the Indenture
referred to below. As an inducement to you to enter into the Purchase Agreement
and in satisfaction of a condition to your obligations thereunder, the Company
agrees with you, (i) for your benefit and (ii) for the benefit of the holders
from time to time of the Securities and the Common Stock issuable upon
conversion of the Securities (including you), as follows:

         Section 1. Definitions. Capitalized terms used herein without
definition shall have the respective meanings set forth in the Purchase
Agreement. As used in this Agreement, the following capitalized terms shall have
the following meanings:

         "ACT" means the Securities Act of 1933, as amended, and the rules and
regulations of the SEC promulgated thereunder.

         "AFFILIATE" of any specified person means any other person, directly or
indirectly, controlling or controlled by or under direct or indirect common
control with such specified person. For the purposes of this definition,
"control" (including, with correlative meanings, the terms "controlling",
"controlled by" and "under common control with"), as used with respect to any
person, shall

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mean the possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of such person, whether through the
ownership of voting securities or by agreement or otherwise.

         "BUSINESS DAY" has the meaning set forth in the Indenture.

         "CLOSING DATE" means June 23, 2003.

         "COMMON STOCK" means the common stock, par value $.001 per share, of
the Company as it exists on the date of this Agreement and any other shares of
capital stock or other securities of the Company into which such Common Stock
may be reclassified or changed, together with any and all other securities which
may from time to time be issuable upon conversion of Securities..

         "DAMAGES PAYMENT DATE" means January 15 and July 15 of each year.

         "DTC" has the meaning set forth in Section 3(k) hereof.

         "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended,
and the rules and regulations of the SEC promulgated thereunder.

         "FINAL MATURITY DATE" means July 15, 2023.

         "HOLDER" means a person who is a holder or beneficial owner (including
the Initial Purchasers) of any Securities or shares of Common Stock issued upon
conversion of Securities; provided that, unless otherwise expressly stated
herein, only registered holders of Securities or Common Stock issued on
conversion thereof shall be counted for purposes of calculating any proportion
of holders entitled to take any action or give notice pursuant to this
Agreement.

         "INDENTURE" means the Indenture relating to the Securities dated as of
June 23, 2003, between the Company and The Bank of New York, as trustee, as the
same may be amended from time to time in accordance with the terms thereof.

         "INITIAL PLACEMENT" has the meaning set forth in the preamble hereto.

         "INITIAL PURCHASERS" has the meaning set forth in the preamble hereto.

         "LIQUIDATED DAMAGES" has the meaning set forth in Section 2(e) hereof.

         "MAJORITY HOLDERS" means the Holders of a majority of the then
outstanding aggregate principal amount of Securities registered under a Shelf
Registration Statement; provided that Holders of Common Stock issued upon
conversion of Securities shall be deemed to be Holders of the aggregate
principal amount of Securities from which such Common Stock was converted; and
provided, further, that Securities or Common Stock that have been sold or
otherwise transferred pursuant to the Shelf Registration Statement shall not be
included in the calculation of Majority Holders.

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         "MAJORITY UNDERWRITING HOLDERS" means, with respect to any Underwritten
Offering, the Holders of a majority of the then outstanding aggregate principal
amount of Securities registered under any Shelf Registration Statement whose
Securities are or are to be included in such Underwritten Offering; provided
that Holders of Common Stock issued upon conversion of Securities should be
deemed to be Holders of the aggregate principal amount of Securities from which
such Common Stock was converted.

         "MANAGING UNDERWRITERS" means the Underwriter or Underwriters that
shall administer an Underwritten Offering.

         "NASD" has the meaning set forth in Section 3(i) hereof.

         "NOTICE AND QUESTIONNAIRE" means a Selling Securityholder Notice and
Questionnaire substantially in the form of Annex A to the Offering Memorandum.

         "OFFERING MEMORANDUM" means the Final Memorandum as defined in the
Purchase Agreement.

         "PERSON" and "person" have the meaning set forth in the Indenture.

         "PROSPECTUS" means the prospectus included in any Shelf Registration
Statement (including, without limitation, a prospectus that discloses
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 430A under the Act), as amended or
supplemented by any prospectus supplement, with respect to the terms of the
offering of any portion of the Securities or Common Stock issuable upon
conversion thereof covered by such Shelf Registration Statement, and all
amendments and supplements to such prospectus, including all documents
incorporated or deemed to be incorporated by reference in such prospectus.

         "PURCHASE AGREEMENT" has the meaning set forth in the preamble hereto.

         "RECORD HOLDER" means with respect to any Damages Payment Date, each
person who is a holder of record of Securities or Common Stock issued upon
conversion thereof on the January 1 or July 1, as the case may be, immediately
preceding the applicable Damages Payment Date.

         "REGISTRATION DEFAULT" has the meaning set forth in Section 2(e)
hereof.

         "REPRESENTATIVE" has the meaning set forth in the preamble thereto.

         "RULE 144" means Rule 144 (or any successor provision) under the Act.

         "SEC" means the Securities and Exchange Commission.

         "SECURITIES" has the meaning set forth in the preamble hereto.

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         "SHELF REGISTRATION" means a registration effected pursuant to Section
2 hereof.

         "SHELF REGISTRATION PERIOD" has the meaning set forth in Section 2(c)
hereof.

         "SHELF REGISTRATION STATEMENT" means a "shelf" registration statement
of the Company pursuant to the provisions of Section 2 hereof which covers all
of the Securities and the Common Stock issuable upon conversion thereof, as
applicable, on Form S-3 or on another appropriate form for an offering to be
made on a delayed or continuous basis pursuant to Rule 415 under the Act, or any
similar rule that may be adopted by the SEC, and all amendments and supplements
to such registration statement, including post-effective amendments, in each
case including the Prospectus contained therein, all exhibits thereto and all
documents incorporated or deemed to be incorporated by reference therein.

         "SUSPENSION PERIOD" has the meaning set forth in Section 2(d) hereof.

         "TRANSFER RESTRICTED SECURITIES" means each Security and any share of
Common Stock issued on conversion thereof until the earlier of the date (A) on
which such Security or share of Common Stock, as the case may be, (i) has been
transferred pursuant to the Shelf Registration Statement or another registration
statement covering such Security or share of Common Stock which has been filed
with the SEC pursuant to the Act, in either case after such registration
statement has become effective and while such registration statement is
effective under the Act, (ii) has been transferred pursuant to Rule 144 (or any
similar provision then in force), or (iii) may be sold or transferred, other
than by our affiliates (as defined in Rule 144), pursuant to Rule 144(k) (or any
similar provision then in force), or (B) that is the second anniversary of the
latest date of issuance of any Securities (including any issuance pursuant to
the Initial Purchasers' option to purchase additional Securities).

         "TRUSTEE" means the trustee with respect to the Securities under the
Indenture.

         "UNDERWRITER" means any underwriter of Securities or Common Stock
issuable upon conversion thereof in connection with an offering thereof under a
Shelf Registration Statement.

         "UNDERWRITTEN OFFERING" means an offering in which the Securities or
Common Stock issued upon conversion thereof are sold to an Underwriter or with
the assistance of an Underwriter for reoffering to the public.

         All references in this Agreement to financial statements and schedules
and other information which is "contained", "included", or "stated" in the Shelf
Registration Statement, any preliminary Prospectus or Prospectus (and all other
references of like import) shall be deemed to mean and include all such
financial

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statements and schedules and other information which is incorporated or deemed
to be incorporated by reference in such Shelf Registration Statement,
preliminary Prospectus or Prospectus, as the case may be; and all references in
this Agreement to amendments or supplements to the Shelf Registration Statement,
any preliminary Prospectus or Prospectus shall be deemed to mean and include the
filing of any document under the Exchange Act, after the date of such Shelf
Registration Statement, preliminary Prospectus or Prospectus, as the case may
be, which is incorporated or deemed to be incorporated by reference therein.

         Section 2. Shelf Registration Statement. (a) The Company shall prepare
and, as soon as reasonably practicable but not later than 90 days following the
Closing Date, shall file with the SEC a Shelf Registration Statement with
respect to resales of the Securities and the Common Stock issuable upon
conversion thereof by the Holders from time to time in accordance with the
methods of distribution elected by such Holders and set forth in such Shelf
Registration Statement and thereafter shall use its reasonable best efforts to
cause such Shelf Registration Statement to be declared effective under the Act
within 180 days after the Closing Date; provided that if any Securities are
issued upon exercise of the option granted to the Initial Purchasers in the
Purchase Agreement and the date on which such Securities are issued occurs after
the Closing Date, the Company will take such reasonable steps, prior to the
effective date of the Shelf Registration Statement, to ensure that such
Securities and Common Stock issuable upon conversion thereof are included in the
Shelf Registration Statement on the same terms as the Securities issued on the
Closing Date. The Company shall supplement or amend the Shelf Registration
Statement if required by the rules, regulations or instructions applicable to
the registration form used by the Company for the Shelf Registration Statement,
if required by the Act, the Exchange Act or the SEC.

         (b)      (1) At the time the Shelf Registration statement is declared
effective, each Holder that has returned a completed and signed Notice and
Questionnaire to the Company on or prior to the date ten (10) Business Days
prior to such time of effectiveness shall be named as a selling securityholder
in the Shelf Registration and the related Prospectus in such a manner as to
permit such Holder to deliver such Prospectus to purchasers of Transfer
Restricted Securities in accordance with applicable law.

                  (2)      From and after the date the Shelf Registration
         Statement is declared effective, the Company shall, as promptly as is
         reasonably practicable after the date a Notice and Questionnaire is
         delivered, and in any event within ten (10) Business Days after such
         date, (i) if required by applicable law, file with the SEC a
         post-effective amendment to the Shelf Registration Statement or prepare
         and, if required by applicable law, file a supplement to the related
         Prospectus or an amendment or supplement to any document incorporated
         therein by reference or file any other required document so that the
         Holder delivering such Notice and Questionnaire is named as a selling
         securityholder in the Shelf Registration Statement and

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         the related Prospectus and so that such Holder is permitted to deliver
         such Prospectus to purchasers of the Securities or Common Stock issued
         or issuable upon conversion thereof in accordance with applicable law
         and, if the Company shall file a post-effective amendment to the Shelf
         Registration Statement, use commercially reasonable efforts to cause
         such post-effective amendment to be declared effective under the Act as
         promptly as is practicable, but in any event within 60 days of the date
         of filing; (ii) provide such Holder copies of any documents filed
         pursuant to clause (i) above; and (iii) notify such Holder as promptly
         as practicable after the effectiveness under the Act of any
         post-effective amendment filed pursuant to clause (i) above; provided,
         that if such Notice and Questionnaire is delivered during a Suspension
         Period (as defined below), the Company shall so inform the Holder
         delivering such Notice and Questionnaire and shall take the actions set
         forth in clauses (i), (ii) and (iii) above upon expiration of the
         Suspension Period. Notwithstanding anything herein to the contrary, the
         Company shall be under no obligation to take any action to name any
         Holder that has not returned a completed Notice and Questionnaire as a
         selling securityholder in the Shelf Registration Statement or related
         Prospectus.

                  (3)      Each Holder agrees to notify the Company as promptly
         as reasonably practicable of any inaccuracy or change in information
         previously furnished by such Holder to the Company or of the occurrence
         of any event in either case as a result of which any Prospectus
         relating to the Shelf Registration Statement contains or would contain
         an untrue statement of a material fact regarding such Holder or such
         Holder's intended method of disposition or omits to state any material
         fact regarding such Holder or such Holder's intended method of
         disposition required to be stated therein or necessary to make the
         statement therein not misleading in light of the circumstances then
         existing. Each Holder further agrees not to sell any Securities or
         Common Stock issuable upon conversion thereof pursuant to the Shelf
         Registration Statement without delivering, or causing to be delivered,
         a Prospectus to the purchaser thereof and, following expiration of the
         Shelf Registration Period, to notify the Company, within ten Business
         Days of a request by the Company, of the aggregate principal amount of
         Securities or the number of shares of Common Stock issuable upon
         conversion thereof sold pursuant to the Shelf Registration Statement
         and, in absence of a response, the Company may assume that all of
         Holder's Securities and Common Stock issuable upon conversion thereof
         were so sold.

         (c)      The Company shall use its reasonable best efforts to keep the
Shelf Registration Statement continuously effective under the Act in order to
permit the Prospectus forming part thereof to be usable by all Holders until
there are no longer any Transfer Restricted Securities (such period while there
are Transfer Restricted Securities being called the "SHELF REGISTRATION
PERIOD"). The

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Company will, subject to Section 2(d), prepare and file with the SEC such
amendments and post-effective amendments to the Shelf Registration Statement as
may be necessary to keep the Shelf Registration Statement continuously effective
for the Shelf Registration Period; subject to Section 2(d), cause the related
Prospectus to be supplemented by any required supplement, and as so supplemented
to be filed pursuant to Rule 424 (or any similar provisions then in force) under
the Act; and, comply in all material respects with the provisions of the Act
with respect to the disposition of all securities covered by the Shelf
Registration Statement during the applicable period in accordance with the
intended methods of disposition by the sellers thereof set forth in such Shelf
Registration Statement as so amended or such Prospectus as so supplemented.

         (d)      The Company may suspend the use of the Prospectus for periods
not to exceed an aggregate of 45 days in any three-month period or for periods
not to exceed an aggregate of 90 days in any twelve-month period (the
"SUSPENSION PERIOD") for valid business reasons, to be determined by the Company
in its sole reasonable judgment (not including avoidance of the Company's
obligations hereunder), including, without limitation, the acquisition or
divestiture of assets, public filings with the SEC, pending corporate
developments and similar events; provided that the Company promptly thereafter
complies with the requirements of Section 3(j) hereof, if applicable; and
provided further, that the existence of a Suspension Period will not prevent the
occurrence of a Registration Default or otherwise limit the obligation of the
Company to pay Liquidated Damages. The Company shall provide notice to the
Holders of a Suspension Period as required under Section 3(c)(1)(iv) hereof. The
Company need not specify the nature of the event giving rise to a Suspension
Period in any notice to Holders.

         (e)      If (i) the Shelf Registration Statement is not filed with the
SEC on or prior to 90 days after the Closing Date, (ii) the Shelf Registration
Statement has not been declared effective by the SEC within 180 days after the
Closing Date, or (iii) the Shelf Registration Statement is filed and declared
effective but shall cease to be effective (without being succeeded immediately
by a replacement shelf registration statement filed and declared effective) or
usable under the Act (other than as a result of a Suspension Period) for the
offer and sale of Transfer Restricted Securities at any time on or after the
181st day following the Closing Date and prior to the expiration of the Shelf
Registration Period, (iv) the Company shall fail to perform its obligations
pursuant to Section 2(b)(2) or (v) Suspension Periods shall exist for a number
of days greater than permitted pursuant to Section 2(d) (each such event
referred to in clauses (i) through (v), a "REGISTRATION DEFAULT"), the Company
will pay liquidated damages ("LIQUIDATED DAMAGES") to each Holder of Transfer
Restricted Securities who has complied with such Holder's obligations under this
Agreement; provided that with respect to a Registration Default pursuant to
clause (iv) above, Liquidated Damages shall only be payable to the Holders who
delivered the Notices and Questionnaires that caused the Company to incur the
obligations set forth in Section 2(b)(2). The amount of Liquidated Damages
payable during any period in

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which a Registration Default has occurred and is continuing is the amount which
is equal to (A) for the first 90 days during which a Registration Default has
occurred and is continuing (1) in respect of any Securities that are Transfer
Restricted Securities, one-quarter of one percent (25 basis points) per annum
per $1,000 principal amount of Securities and (2) in respect of any shares of
Common Stock issued upon conversion of Securities that are Transfer Restricted
Securities, one-quarter of one percent (25 basis points) per annum of the
then-effective Conversion Price (as defined in the Indenture) per share of
Common Stock and (B) for any additional days during which a Registration Default
has occurred and is continuing (1) in respect of any Securities that are
Transfer Restricted Securities, one-half of one percent (50 basis points) per
annum per $1,000 principal amount of Securities and (2) in respect of any shares
of Common Stock issued upon conversion of Securities that are Transfer
Restricted Securities, one-half of one percent (50 basis points) per annum of
the then-effective Conversion Price (as defined in the Indenture) per share of
Common Stock, it being understood that all calculations pursuant to this and the
preceding sentence shall be carried out to five decimals. Following the cure of
all Registration Defaults, Liquidated Damages will cease to accrue with respect
to such Registration Default, it being acknowledged and agreed that a
Registration Default shall be deemed cured upon (A) the filing of a Shelf
Registration Statement (in the case of Section 2(e)(i) hereof), (B) the
effectiveness of a Shelf Registration Statement (in the case of Section 2(e)(ii)
hereof), (C) the effectiveness or usability under the Act of a Shelf
Registration Statement that ceased to be effective or usable (Section 2(e)(iii)
hereof), (D) the Company fulfilling it obligations under Section 2(b)(2) (in the
case of Section 2(e)(iv) hereof) and (E) the termination of the Suspension
Period that caused the limit on the aggregate duration of the Suspension Periods
to be exceeded (in the case of Section 2(e)(v) hereof). In no event shall
Liquidated Damages accrue based on more than one Registration Default at any
given time and in no event shall the Liquidated Damages rate exceed in the
aggregate one-half of one percent per annum. All accrued Liquidated Damages
shall be paid by wire transfer of immediately available funds or by federal
funds check by the Company to Record Holders on each Damages Payment Date and
Liquidated Damages will be calculated on the basis of a 360-day year consisting
of twelve 30-day months. The parties hereto agree that the Liquidated Damages
provided for in this Section 2(e) constitute a reasonable estimate of the
damages that may be incurred by Holders by reason of a Registration Default. The
Liquidated Damages set forth in this Section 2(e) shall be the exclusive damages
remedy of the Initial Purchasers and each Holder of Transfer Restricted
Securities for any Registration Default; provided, however, that nothing herein
shall prevent a suit by any Holder for specific performance.

         (f)      All of the Company's obligations (including, without
limitation, the obligation to pay Liquidated Damages) set forth in the preceding
paragraph which are outstanding or exist with respect to any Transfer Restricted
Security at the time such security ceases to be a Transfer Restricted Security
shall survive until such time as all such obligations with respect to such
security shall have been

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satisfied in full (it being acknowledged and agreed that the Liquidated Damages
shall not continue to accrue after such time as a Transfer Restricted Security
ceases to be such).

         (g)      Immediately upon the occurrence or the termination of a
Registration Default, the Company shall give the Trustee, in the case of notice
with respect to the Securities, and the transfer and paying agent for the Common
Stock, in the case of notice with respect to Common Stock issued or issuable
upon conversion thereof, notice of such commencement or termination, of the
obligation to pay Liquidated Damages with regard to the Securities and Common
Stock and the amount thereof and of the event giving rise to such commencement
or termination (such notice to be contained in an Officers' Certificate (as such
term is defined in the Indenture)), and prior to receipt of such Officers'
Certificate the Trustee and such transfer and paying agent shall be entitled to
assume that no such commencement or termination has occurred, as the case may
be.

         (h)      All Securities which are redeemed, purchased or otherwise
acquired by the Company or any of its subsidiaries prior to the Final Maturity
Date shall be delivered to the Trustee for cancellation and the Company may not
hold or resell such Securities or issue any new Securities to replace any such
Securities or any Securities that any Holder has converted pursuant to the
Indenture. All shares of Common Stock issued upon conversion of the Securities
which are repurchased or otherwise acquired by the Company or any of its
subsidiaries at any time while such shares are "restricted securities" within
the meaning of Rule 144 shall not be resold or otherwise transferred except
pursuant to a registration statement which has been declared effective under the
Act.

         Section 3. Registration Procedures. In connection with any Shelf
Registration Statement, the following provisions shall apply:

         (a)      The Company shall furnish to you, prior to the filing thereof
with the SEC, a copy of any Shelf Registration Statement, and each amendment
thereof (excluding amendments caused by the filing by the Company with the SEC
of a report required by the Exchange Act), a copy of any Prospectus, and each
amendment or supplement, if any, to the Prospectus included therein and shall
use its reasonable best efforts to reflect in each such document, when so filed
with the SEC, such comments as Citigroup Global Markets Inc. reasonably may
propose. Citigroup Global Markets Inc. shall promptly furnish to the Company any
comments it may have to such documents mentioned in the foregoing sentence.

         (b)      The Company shall ensure that (i) any Shelf Registration
Statement and any amendment thereto and any Prospectus forming part thereof and
any amendment or supplement thereto comply in all material respects with the Act
and the rules and regulations thereunder, (ii) any Shelf Registration Statement
and any amendment thereto does not, when it becomes effective, contain an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading and
(iii) any

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Prospectus forming part of any Shelf Registration Statement, and any amendment
or supplement to such Prospectus, does not include an untrue statement of a
material fact or omit to state a material fact necessary in order to make the
statements therein, in light of the circumstances under which they were made,
not misleading; provided that the Company makes no representation or agreement
with respect to information with respect to you, any Underwriter or any Holder
included in any Shelf Registration or Prospectus in reliance upon and in
conformity with information furnished to the Company in writing by you, any
Underwriter or any such Holder.

         (c)      (1) The Company, as promptly as reasonably practicable, shall
advise you and each Holder that has returned a completed and signed Notice and
Questionnaire to the Company and, if requested by you or any such Holder,
confirm such advice in writing: (i) when a Shelf Registration Statement and any
amendment thereto has been filed with the SEC and when the Shelf Registration
Statement or any post-effective amendment thereto has become effective; of any
request by the SEC for amendments or supplements to the Shelf Registration
Statement or the Prospectus or for additional information; (iii) of the
determination by the Company that a post-effective amendment to the Shelf
Registration Statement would be appropriate; and of the commencement or
termination of any Suspension Period.

                  (2)      The Company shall advise you and each Holder that has
         returned a completed and signed Notice and Questionnaire to the Company
         and, if requested by you or any such Holder, confirm such advice in
         writing: (i) of the issuance by the SEC of any stop order suspending
         the effectiveness of the Shelf Registration Statement or the initiation
         of any proceedings for that purpose; (ii) of the receipt by the Company
         of any notification with respect to the suspension of the qualification
         of the Securities included in any Shelf Registration Statement for sale
         in any jurisdiction or the initiation or threat of any proceeding for
         such purpose; and (iii) of the suspension of the use of the Prospectus
         pursuant to Section 2(d) hereof or of the happening of any event that
         requires the making of any changes in the Shelf Registration Statement
         or the Prospectus so that, as of such date, the statements therein are
         not misleading and the Shelf Registration Statement or the Prospectus,
         as the case may be, does not include an untrue statement of a material
         fact or omit to state a material fact required to be stated therein or
         necessary to make the statements therein (in the case of the
         Prospectus, in light of the circumstances under which they were made)
         not misleading (which advice shall be accompanied by an instruction to
         suspend the use of the Prospectus until the requisite changes have been
         made).

         (d)      The Company shall use its reasonable best efforts to obtain
the withdrawal of any order suspending the effectiveness of any Shelf
Registration Statement or the lifting of any suspension of the qualification (or
exemption from

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qualification) of any of the Securities for offer or sale in any jurisdiction as
soon as reasonably practicable.

         (e)      The Company shall furnish to each Holder of Securities and the
Common Stock issued upon conversion thereof included within the coverage of any
Shelf Registration Statement, without charge, one copy of such Shelf
Registration Statement and any post-effective amendment thereto, including
financial statements and schedules, and, if the Holder so requests in writing,
all exhibits (including those incorporated by reference).

         (f)      The Company shall, during the Shelf Registration Period,
deliver to each Holder of Securities or the Common Stock issued upon conversion
thereof included within the coverage of any Shelf Registration Statement,
without charge, as many copies of the Prospectus (including each preliminary
Prospectus) included in such Shelf Registration Statement and any amendment or
supplement thereto as such Holder may reasonably request; and, except during the
continuance of any Suspension Period, the Company consents to the use of the
Prospectus or any amendment or supplement thereto by each of the selling Holders
in connection with the offering and sale of the Securities or the Common Stock
issued upon conversion thereof covered by the Prospectus or any amendment or
supplement thereto.

         (g)      Prior to any offering of Securities or the Common Stock issued
upon conversion thereof pursuant to any Shelf Registration Statement, the
Company shall register or qualify or cooperate with the Holders of Securities
and the Common Stock issued upon conversion thereof included therein and their
respective counsel in connection with the registration or qualification (or
exemption from such registration or qualification), if necessary, of such
Securities or Common Stock for offer and sale, as the case may be, under the
securities or blue sky laws of such jurisdictions as any such Holders reasonably
request in writing and do any and all other acts or things necessary or
advisable to enable the offer and sale in such jurisdictions of the Securities
and the Common Stock issued upon conversion thereof covered by such Shelf
Registration Statement; provided, however, that the Company will not be required
to (A) qualify generally to do business in any jurisdiction where it is not then
so qualified or to (B) take any action which would subject it to general service
of process or to taxation in any such jurisdiction where it is not then so
subject.

         (h)      The Company shall cooperate with the Holders to facilitate the
timely preparation and delivery of certificates representing Securities or the
Common Stock issued upon conversion thereof to be sold pursuant to any Shelf
Registration Statement free of any restrictive legends and in such denominations
and registered in such names as Holders may request.

         (i)      Subject to the exceptions contained in (A) and (B) of
subsection (g) hereof, the Company shall use its reasonable best efforts to
cause the Securities and Common Stock issued upon conversion thereof covered by
the applicable

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Shelf Registration Statement to be registered with or approved by such other
federal, state and local governmental agencies or authorities, and
self-regulatory organizations in the United States as may be necessary to enable
the Holders to consummate the disposition of such Securities and Common Stock
issued upon conversion thereof as contemplated by the Shelf Registration
Statement; without limitation to the foregoing, the Company shall make all
filings and provide all such information as may be required by the National
Association of Securities Dealers, Inc. (the "NASD") in connection with the
offering under the Shelf Registration Statement of the Securities and Common
Stock issued upon conversion thereof (including, without limitation, such as may
be required by NASD Rule 2710 or 2720), and shall cooperate with each Holder in
connection with any filings required to be made with the NASD by such Holder in
that regard.

         (j)      Upon the occurrence of any event contemplated by paragraph
3(c)(2)(iii) above and subject to Section 3(a) hereof, the Company shall
promptly prepare and file with the SEC a post-effective amendment to any Shelf
Registration Statement or an amendment or supplement to the related Prospectus
or any document incorporated therein by reference or file a document which is
incorporated or deemed to be incorporated by reference in such Shelf
Registration Statement or Prospectus, as the case may be, so that, as thereafter
delivered to purchasers of the Securities or the Common Stock issued upon
conversion thereof included therein, the Shelf Registration Statement and the
Prospectus, in each case as then amended or supplemented, will not include an
untrue statement of a material fact or omit to state any material fact required
to be stated therein or necessary in order to make the statements therein (in
the case of the Prospectus in light of the circumstances under which they were
made) not misleading and in the case of a post-effective amendment, use its
reasonable best efforts to cause it to become effective as promptly as
practicable; provided that the Company's obligations under this paragraph (j)
shall be suspended if the Company has suspended the use of the Prospectus in
accordance with Section 2(d) hereof and given notice of such suspension to
Holders, it being understood that the Company's obligations under this
Subsection (j) shall be automatically reinstated at the end of such Suspension
Period.

         (k)      The Company shall use its reasonable best efforts to cause The
Depository Trust Company ("DTC") on the first Business Day following the
effective date of any Shelf Registration Statement hereunder or as soon as
reasonably practicable thereafter to remove (i) from any existing CUSIP number
assigned to the Securities any designation indicating that the Securities are
"restricted securities", which efforts shall include delivery to DTC of a letter
executed by the Company substantially in the form of Exhibit A hereto and (ii)
any other stop or restriction on DTC's system with respect to the Securities. In
the event the Company is unable to cause DTC to take actions described in the
immediately preceding sentence, the Company shall take such actions as Citigroup
Global Markets Inc. may reasonably request to provide, as soon as

                                       12

<PAGE>

reasonably practicable, a CUSIP number for the Securities registered under such
Shelf Registration Statement and to cause such CUSIP number to be assigned to
such Securities (or to the maximum aggregate principal amount of the Securities
to which such number may be assigned). Upon compliance with the foregoing
requirements of this Section 3(k), the Company shall provide the Trustee with
global certificates for such Securities in a form eligible for deposit with DTC.

         (l)      The Company shall use its reasonable best efforts to comply
with all applicable rules and regulations of the SEC and shall make generally
available to its security holders earnings statements (which need not be
audited) satisfying the provisions of Section 11(a) of the Act and Rule 158
thereunder (or any similar rule promulgated under the Act) no later than 45 days
after the end of any 12-month period (or 90 days after the end of any 12-month
period if such period is a fiscal year) commencing on the first day of the first
fiscal quarter of the Company commencing after the effective date of the Shelf
Registration Statement (as the effective date of a registration statement is
defined in Rule 158(c)), which statements shall cover said 12-month period.

         (m)      The Company shall use its reasonable best efforts to cause the
Indenture to be qualified under the TIA (as defined in the Indenture) in a
timely manner.

         (n)      The Company shall cause all Common Stock issued or issuable
upon conversion of the Securities to be listed on each securities exchange or
quotation system on which the Common Stock is then listed no later than the date
the applicable Shelf Registration Statement is declared effective and, in
connection therewith, to make such filings as may be required under the Exchange
Act and to have such filings declared effective as and when required thereunder.

         (o)      The Company may require each Holder of Securities or the
Common Stock issued upon conversion thereof to be sold pursuant to any Shelf
Registration Statement to furnish to the Company such information regarding the
Holder and the distribution of such Securities or Common Stock sought by the
Notice and Questionnaire and such additional information as may, from time to
time, be required by the Act and the rules and regulations promulgated
thereunder, and the obligations of the Company to any Holder hereunder
(including, without limitation, the payment of Liquidated Damages) shall be
expressly conditioned on the compliance of such Holder with such request.

         (p)      The Company shall, if reasonably requested, use its reasonable
best efforts to promptly incorporate in a Prospectus supplement or
post-effective amendment to a Shelf Registration Statement (i) such information
as the Majority Holders provide or, if the Securities or Common Stock are being
sold in an Underwritten Offering, as the Managing Underwriters or the Majority
Underwriting Holders reasonably agree should be included therein and provide to
the Company in writing for inclusion in the Shelf Registration Statement or

                                       13

<PAGE>

Prospectus, and (ii) such information as a Holder may provide from time to time
to the Company in writing for inclusion in a Prospectus or any Shelf
Registration Statement concerning such Holder and the distribution of such
Holder's Securities and Common Stock and, in either case, shall make all
required filings of such Prospectus supplement or post-effective amendment as
soon as reasonably practicable after being notified in writing of the matters to
be incorporated in such Prospectus supplement or post-effective amendment,
provided that the Company shall not be required to take any action under this
Section 3(p) that is not, in the reasonable opinion of counsel for the Company,
in compliance with applicable law.

         (q)      The Company shall enter into such customary agreements
(including underwriting agreements) and take all other appropriate actions as
may be reasonably requested in order to expedite or facilitate the registration
or the disposition of the Securities or the Common Stock issued or issuable upon
conversion thereof. The plan of distribution in the Shelf Registration Statement
and the Prospectus included therein shall permit resales of the Securities or
Common Stock issuable upon conversion thereof to be made by selling security
holders through underwriters, brokers and dealers, and shall also include such
other information as Citigroup Global Markets Inc. may reasonably request.

         (r)      In connection with any Underwritten Offering, the Company
shall (i) make reasonably available for inspection by any Underwriter
participating in any disposition pursuant to such Shelf Registration Statement,
and any attorney, accountant or other agent retained by any such Underwriter all
relevant financial and other records, pertinent corporate documents and
properties of the Company and its subsidiaries as is customary for due diligence
examinations in connection with Underwritten Offerings; (ii) cause the Company's
officers to supply all relevant information reasonably requested by any such
Underwriter, attorney, accountant or agent in connection with any such Shelf
Registration Statement as is customary for similar due diligence examinations;
provided, however, that any information that is designated in writing by the
Company, in its sole discretion, as confidential at the time of delivery of such
information shall be kept confidential by any such Underwriter, attorney,
accountant or agent, unless disclosure thereof is made in connection with a
court, administrative or regulatory proceeding or required by law, or such
information has become available to the public generally through the Company or
through a third party without an accompanying obligation of confidentiality;
provided, further, that if the foregoing inspection and information gathering
specified in subsections (i) and (ii) would, in the Company's reasonable
judgment, disrupt the Company's conduct of business, such inspections and
information gathering shall be coordinated on behalf of the Underwriters and the
other parties entitled thereto by one counsel designated by or on behalf of the
Majority Underwriting Holders and the Managing Underwriters; (iii) make such
representations and warranties to the Underwriters, in form, substance and scope
as are customarily made by issuers to Underwriters; (iv) obtain opinions of
counsel to the Company and updates thereof (which

                                       14

<PAGE>

counsel and opinions, in form, scope and substance, shall be reasonably
satisfactory to the Managing Underwriters) addressed to the Underwriters
covering such matters as are customarily covered in opinions requested in
Underwritten Offerings; (v) obtain "cold comfort" letters and updates thereof
from the independent certified public accountants of the Company (and, if
necessary, any other independent certified public accountants of any subsidiary
of the Company or of any business acquired by the Company for which financial
statements and financial data are, or are required to be, included in the Shelf
Registration Statement), addressed to the Underwriters in customary form and
covering matters of the type customarily covered in "cold comfort" letters in
connection with primary Underwritten Offerings; and (vi) deliver such documents
and certificates as may be reasonably requested by the Majority Underwriting
Holders and the Managing Underwriters, including those to evidence compliance
with Section 3(j) and with any customary conditions contained in the
underwriting agreement or other agreement entered into by the Company. The
foregoing actions set forth in clauses (iii), (iv), (v) and (vi) of this Section
3(r) shall be performed at (A) the effectiveness of such Shelf Registration
Statement relating to an Underwritten Offering and each post-effective amendment
thereto and (B) each closing under any underwriting or similar agreement as and
to the extent required thereunder.

         (s)      Each Holder agrees that, upon receipt of notice of the
happening of an event described in Section 3(c)(1)(ii) through and including
Section 3(c)(1)(iv) and Sections 3(c)(2)(i) through and including 3(c)(2)(iii),
each Holder shall forthwith discontinue (and shall cause its agents and
representatives to discontinue) disposition of the Securities and the Common
Stock issuable upon conversion thereof and will not resume disposition of such
Securities or the Common Stock until such Holder has received copies of an
amended or supplemented Prospectus contemplated by Section 3(j) hereof, or until
such Holder is advised in writing by the Company that the use of the Prospectus
may be resumed or that the relevant Suspension Period has been terminated, as
the case may be, provided that, the foregoing shall not prevent the sale,
transfer or other disposition of Securities or Common Stock issuable upon
conversion thereof by a Holder in a transaction which is exempt from, or not
subject to, the registration requirements of the Act, so long as such Holder
does not and is not required to deliver the applicable Prospectus or Shelf
Registration Statement in connection with such sale, transfer or other
disposition, as the case may be; and provided, further, that the provisions of
this paragraph (s) shall not prevent the occurrence of a Registration Default or
otherwise limit the obligation of the Company to pay Liquidated Damages.

         (t)      Anything herein to contrary notwithstanding, the Shelf
Registration Statement may not be used for an Underwritten Offering without the
prior written consent of the Company. Notwithstanding anything to the contrary
contained herein, if the Managing Underwriters for an Underwritten Offering
advise the Holders of the Securities and shares of the Common Stock to be
included in such

                                       15

<PAGE>

Underwritten Offering that, because of the aggregate principal amount of
Securities and/or number of shares of Common Stock that such Holders have
requested be included in the Underwritten Offering, the success of the offering
would likely be materially adversely affected by the inclusion of all of the
Securities and shares of Common Stock requested to be included, then the
principal amount of Securities and the number of shares of Common Stock to be
offered for the accounts of Holders shall be reduced pro rata, according to the
aggregate principal amount of Securities and number of shares of Common Stock,
respectively, requested for inclusion by each such Holder, to the extent
necessary to reduce the size of the offering to the size recommended by the
Managing Underwriter. Notwithstanding anything to the contrary contained herein,
neither the Company nor any Person, other than a Holder of Securities or shares
of Common Stock issued or issuable upon conversion thereof and only with respect
to its Transfer Restricted Securities, shall be entitled to include any
securities in the Underwritten Offering.

         Section 4. Registration Expenses. The Company shall bear all expenses
incurred in connection with the performance of its obligations under Sections 2
and 3 hereof and shall reimburse the Holders for the reasonable fees and
disbursements of one firm or counsel designated by the Majority Holders to act
as counsel for the Holders in connection therewith. Notwithstanding the
provisions of this Section 4, each Holder shall bear the expense of any broker's
commission, agency fee, Underwriter's discount or commission or transfer taxes.

         Section 5. Indemnification and Contribution. (i) The Company agrees to
indemnify and hold harmless each Holder of Securities and each Holder of Common
Stock issued upon conversion thereof covered by any Shelf Registration Statement
(including the Initial Purchasers), the directors, officers, employees and
agents of each such Holder and each person who controls any such Holder within
the meaning of either the Act or the Exchange Act against any and all losses,
claims, damages or liabilities, joint or several, to which they or any of them
may become subject under the Act, the Exchange Act or other Federal or state law
or regulation, at common law or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon any untrue statement or alleged untrue statement of a material fact
contained in the Shelf Registration Statement as originally filed or in any
amendment thereof, or in any preliminary Prospectus or Prospectus, or in any
amendment thereof or supplement thereto, or arise out of or are based upon the
omission or alleged omission to state therein a material fact required to be
stated therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading, and agrees to
reimburse each such indemnified party for any legal or other expenses reasonably
incurred by any of them in connection with investigating or defending any such
loss, claim, damage, liability or action; provided, however, that the Company
will not be liable in any such case to the extent that any such loss, claim,
damage or liability arises out of or is based upon (A) any such untrue statement
or alleged untrue statement or omission or alleged

                                       16

<PAGE>

omission made therein in reliance upon and in conformity with written
information furnished to the Company by or on behalf of any such Holder or any
Initial Purchaser specifically for inclusion therein, (B) use of a Shelf
Registration Statement or the related Prospectus during a period when a stop
order has been issued in respect of such Shelf Registration or any proceedings
for that purpose have been initiated or use of a Prospectus when use of such
Prospectus has been suspended pursuant to Section 2(d) or Section 3(s);
provided, further, in each case, that Holders received prior notice of such stop
order, initiation of proceedings or suspension, or (C) such Holder's failure to
deliver a Prospectus, as then amended or supplemented, provided that the Company
shall have delivered to such Holder such Prospectus, as then amended or
supplemented. This indemnity agreement will be in addition to any liability
which the Company may otherwise have.

                  (ii)     The Company also agrees to indemnify and to
         contribute to Losses, as provided in Section 5(d), of any Underwriters
         of Securities or Common Stock issued upon conversion thereof registered
         under a Shelf Registration Statement, their officers and directors and
         each person who controls any such Underwriter within the meaning of
         either the Act or the Exchange Act on substantially the same basis as
         that of the indemnification of the Initial Purchasers and the selling
         Holders provided in this Section 5(a) and shall, if requested by any
         Holder, enter into an underwriting agreement reflecting such agreement,
         as provided in Section 3(q) hereof. This indemnity agreement will be in
         addition to any liability which the Company may otherwise have.

         (b)      Each Holder of Securities or Common Stock issued upon
conversion thereof covered by a Shelf Registration Statement (including the
Initial Purchasers) severally and not jointly agrees to indemnify and hold
harmless (i) the Company, (ii) each of its directors, (iii) each of its officers
who signs such Shelf Registration Statement and (iv) each person who controls
the Company within the meaning of either the Act or the Exchange Act to the same
extent as the foregoing indemnity from the Company to each such Holder, but only
with reference to written information relating to such Holder furnished to the
Company by or on behalf of such Holder specifically for inclusion in the
documents referred to in the foregoing indemnity. This indemnity agreement will
be in addition to any liability which any such Holder may otherwise have.

         (c)      Promptly after receipt by an indemnified party under this
Section 5 of notice of the commencement of any action, such indemnified party
will, if a claim in respect thereof is to be made against the indemnifying party
under this Section 5, notify the indemnifying party in writing of the
commencement thereof; but the failure so to notify the indemnifying party (i)
will not relieve it from liability under paragraph (a) or (b) above unless and
to the extent it did not otherwise learn of such action and such failure results
in the forfeiture by the indemnifying party of substantial rights and defenses;
and (ii) will not, in any event, relieve the indemnifying party from any
obligations to any indemnified

                                       17

<PAGE>

party other than the indemnification obligation provided in paragraph (a) or (b)
above. The indemnifying party shall be entitled to appoint counsel of the
indemnifying party's choice at the indemnifying party's expense to represent the
indemnified party in any action for which indemnification is sought (in which
case the indemnifying party shall not thereafter be responsible for the fees and
expenses of any separate counsel retained by the indemnified party or parties
except as set forth below); provided, however, that such counsel shall be
reasonably satisfactory to the indemnified party. Notwithstanding the
indemnifying party's election to appoint counsel to represent the indemnified
party in an action, the indemnified party shall have the right to employ
separate counsel (including local counsel), and the indemnifying party shall
bear the reasonable fees, costs and expenses of such separate counsel (including
local counsel) if (i) the use of counsel chosen by the indemnifying party to
represent the indemnified party would present such counsel with a conflict of
interest; (ii) the actual or potential defendants in, or targets of, any such
action include both the indemnified party and the indemnifying party and the
indemnified party shall have reasonably concluded that there may be legal
defenses available to it and/or other indemnified parties which are different
from or additional to those available to the indemnifying party; (iii) the
indemnifying party shall not have employed counsel satisfactory to the
indemnified party to represent the indemnified party within a reasonable time
after notice of the institution of such action; or (iv) the indemnifying party
shall authorize the indemnified party to employ separate counsel at the expense
of the indemnifying party. Notwithstanding the foregoing, the Company shall not,
in the connection with any one 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 counsel (in addition to
one separate local counsel) at any time for the indemnified parties. An
indemnifying party will not, without the prior written consent of the
indemnified party, which consent will not be unreasonably withheld, settle or
compromise or consent to the entry of any judgment with respect to any pending
or threatened claim, action, suit or proceeding in respect of which
indemnification or contribution may be sought hereunder (whether or not the
indemnified parties are actual or potential parties to such claim or action)
unless such settlement, compromise or consent includes an unconditional release
of such indemnified party from all liability arising out of such claim, action,
suit or proceeding. The Company shall not be liable for any losses, claims,
damages or liabilities by reason of any settlement of any action or proceeding
effected without the Company's prior written consent, which consent will not be
unreasonably withheld.

         (d)      In the event that the indemnity provided in paragraph (a) or
(b) of this Section 5 is unavailable to or insufficient to hold harmless an
indemnified party for any reason, then each applicable indemnifying party, in
lieu of indemnifying such indemnified party, shall have an obligation to
contribute to the aggregate losses, claims, damages and liabilities (including
legal or other

                                       18

<PAGE>

expenses reasonably incurred in connection with investigating or defending same)
(collectively "LOSSES"), as incurred, to which such indemnified party may be
subject in such proportion as is appropriate to reflect the relative benefits
received by such indemnifying party, on the one hand, and such indemnified
party, on the other hand, from the Initial Placement and the Shelf Registration
Statement which resulted in such Losses; provided, however, that in no case
shall the Initial Purchasers be responsible, in the aggregate, for any amount in
excess of the purchase discount or commission applicable to the Securities, nor
shall any Underwriter be responsible for any amount in excess of the
underwriting discount or commission applicable to the Securities and Common
Stock issued upon conversion thereof purchased by such Underwriter under the
Shelf Registration Statement which resulted in such Losses. If the allocation
provided by the immediately preceding sentence is unavailable for any reason,
the indemnifying party and the indemnified party shall contribute in such
proportion as is appropriate to reflect not only such relative benefits but also
the relative fault of such indemnifying party, on the one hand, and such
indemnified party, on the other hand, in connection with the statements or
omissions which resulted in such Losses as well as any other relevant equitable
considerations. Benefits received by the Company shall be deemed to be equal to
the total net proceeds from the Initial Placement (before deducting expenses).
Benefits received by the Initial Purchasers shall be deemed to be equal to the
total purchase discounts and commissions received, and benefits received by any
other Holders shall be deemed to be equal to the value of receiving Securities
or the Common Stock issuable upon conversion thereof registered under the Act.
Benefits received by any Underwriter shall be deemed to be equal to the total
underwriting discounts and commissions, as set forth on the cover page of the
Prospectus forming a part of the Shelf Registration Statement (or the applicable
Prospectus supplement) which resulted in such Losses. Relative fault shall be
determined by reference to whether any untrue statement or omission or alleged
untrue statement or omission relates to information provided by the indemnifying
party, on the one hand, or by the indemnified party, on the other hand. The
parties agree that it would not be just and equitable if contribution were
determined by pro rata allocation or any other method of allocation which does
not take account of the equitable considerations referred to above.
Notwithstanding the provisions of this paragraph (d), 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. For purposes of this Section 5, each person who
controls a Holder within the meaning of either the Act or the Exchange Act and
each director, officer, employee and agent of such Holder shall have the same
rights to contribution as such Holder, and each person who controls the Company
within the meaning of either the Act or the Exchange Act, each officer of the
Company who shall have signed the Shelf Registration Statement and each director
of the Company shall have the same rights to contribution as the Company, and
each person who controls an Underwriter within the meaning of either the Act or
the Exchange Act and each officer and director of each

                                       19

<PAGE>

Underwriter shall have the same rights to contribution as such Underwriter,
subject in each case to the applicable terms and conditions of this paragraph
(d).

         (e)      The provisions of this Section 5 will remain in full force and
effect, regardless of any investigation made by or on behalf of any Holder, any
Underwriter or the Company or any of the officers, directors or controlling
persons referred to in Section 5 hereof, and will survive the sale by a Holder
of Securities or shares of Common Stock covered by a Shelf Registration
Statement.

         Section 6. Miscellaneous.

         (a)      No Inconsistent Agreements. The Company has not, as of the
date hereof, entered into nor shall it, on or after the date hereof, enter into,
any agreement with respect to its securities that is inconsistent with the
rights granted to the Holders herein or otherwise conflicts with the provisions
hereof.

         (b)      Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, qualified,
modified or supplemented, and waivers or consents to departures from the
provisions hereof may not be given, unless the Company has obtained the written
consent of the Majority Holders and complied with the provisions of the
Indenture, if applicable; provided that with respect to any matter that directly
or indirectly affects the rights of the Initial Purchasers hereunder, the
Company shall obtain the written consent of each of the Initial Purchasers
against which such amendment, qualification, supplement, waiver or consent is to
be effective. Notwithstanding the foregoing (except the foregoing proviso), a
waiver or consent to departure from the provisions hereof with respect to a
matter that relates exclusively to the rights of Holders whose Securities or
Common Stock are being sold pursuant to a Shelf Registration Statement and that
does not directly or indirectly affect the rights of other Holders may be given
by the Majority Holders, determined on the basis of Securities or Common Stock
issued upon conversion thereof being sold rather than registered under such
Shelf Registration Statement.

         (c)      Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, first-class mail,
telecopier, or air courier guaranteeing overnight delivery: (1) if to you,
initially at the address set forth in the Purchase Agreement; (2) if to any
other Holder, at the most current address given by such Holder to the Company in
accordance with the provisions of this Section 6(c), which address initially is,
with respect to each Holder, the address of such Holder maintained by the
Registrar under the Indenture or, in the case of Common Stock, the address
maintained by the registrar of the Common Stock, with a copy in like manner to
Citigroup Global Markets Inc.; and (3) if to the Company, initially at its
address set forth in the Purchase Agreement. All such notices and communications
shall be deemed to have been duly given when received, if delivered by hand or
air courier, and when sent, if sent by first-class mail or telecopier. The
Initial Purchasers or the

                                       20

<PAGE>

Company by notice to the other may designate additional or different addresses
for subsequent notices or communications.

         (d)      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 the need for an express assignment or any consent by
the Company thereto, subsequent Holders. The Company hereby agrees to extend the
benefits of this Agreement to any Holder and Underwriter and any such Holder and
Underwriter may specifically enforce the provisions of this Agreement as if an
original party hereto. In the event that any other person shall succeed to the
Company under the Indenture as provided in Article 5 thereof, then such
successor shall enter into an agreement, in form and substance reasonably
satisfactory to the Initial Purchasers, whereby such successor shall assume all
of the Company's obligations under this Agreement.

         (e)      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.

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

         (g)      GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO
AGREEMENTS MADE AND TO BE PERFORMED IN SAID STATE, WITHOUT REGARD, TO THE EXTENT
PERMITTED BY APPLICABLE LAW, TO THE CONFLICTS OF LAW RULES THEREOF.

         (h)      Severability. In the event that any one of more of the
provisions contained herein, or the application thereof in any circumstances, is
held invalid, illegal or unenforceable in any respect for any reason, the
validity, legality and enforceability of any such provision in every other
respect and of the remaining provisions hereof shall not be in any way impaired
or affected thereby, it being intended that all of the rights and privileges of
the parties shall be enforceable to the fullest extent permitted by law.

         (i)      Securities Held by the Company, etc. Whenever the consent or
approval of Holders of a specified percentage of principal amount of Securities
or the Common Stock issuable upon conversion thereof is required hereunder,
Securities or the Common Stock issued upon conversion thereof held by the
Company or its Affiliates (other than subsequent Holders of Securities or the
Common Stock issued upon conversion thereof if such subsequent Holders are
deemed to be Affiliates solely by reason of their holdings of such Securities)
shall not be counted in determining whether such consent or approval was given
by the Holders of such required percentage.

                                       21

<PAGE>

Please confirm that the foregoing correctly sets forth the agreement between the
Company and you.

                                           Very truly yours,

                                           DOUBLECLICK INC.

                                           /s/ Kevin P. Ryan
                                           -------------------------------------
                                           Name:  Kevin P. Ryan
                                           Title: Chief Executive Officer

The foregoing Agreement is hereby
confirmed and accepted as of the date
first above written.

CITIGROUP GLOBAL MARKETS INC.

For themselves and the other Initial Purchases named in Schedule I to the
Purchase Agreement

BY: CITIGROUP GLOBAL MARKETS INC.

By: /s/ Theresa Pope
    ----------------------------------
    Name:  Theresa Pope
    Title: Director

                                       22

<PAGE>

                                                                       EXHIBIT A

                   FORM OF LETTER TO BE PROVIDED BY ISSUER TO
                          THE DEPOSITORY TRUST COMPANY

The Depository Trust Company
55 Water Street
New York, NY 10041

Re.      Zero Coupon Convertible Subordinated Notes due 2023 (the "SECURITIES")
         of DoubleClick Inc.

Ladies and Gentlemen:

         Please be advised that the Securities and Exchange Commission has
declared effective a Registration Statement on Form S-3 under the Securities Act
of 1933, as amended, with regard to all of the Securities referenced above.
Accordingly, there is no longer any restriction as to whom such Securities may
be sold and any restrictions on the CUSIP designation are no longer appropriate
and may be removed. I understand that upon receipt of this letter, DTC will
remove any stop or restriction on its system with respect to this issue. As
always, please do not hesitate to call if we can of further assistance.

                                           Very truly yours,

                                           By: _________________________________
                                               Authorized Officer

                                       23