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Exhibit 10.004

SECOND AMENDMENT

        This SECOND AMENDMENT (this "Amendment") is made as of July 1, 2003 by
and between BNP PARIBAS LEASING CORPORATION, a Delaware corporation (as
successor in interest to BNP Leasing Corporation) ("BNPLC"), and CHIRON
CORPORATION, a Delaware corporation ("Chiron").

Recitals

        A.    BNPLC and Chiron executed, among other things, a Lease Agreement
(as amended, the "Lease") a Purchase Agreement (as amended, the "Purchase
Agreement") dated as June 28, 1996 (but effective as of July 1, 1996), and a
Ground Lease (as amended, the "Ground Lease") dated as June 28, 1996 (but
effective as of July 1, 1996), covering the Property located in Emeryville,
Alameda County, California.

        B.    Chiron has previously completed construction of the initial
Construction Project described in Exhibit C of the Lease pursuant to the terms
of the Lease, and all Construction Advances have been previously made.

        C.    Anticipating Chiron's request for this amendment, BNP Paribas, San
Francisco Branch, has on behalf of BNPLC requested the prior written approval of
this Amendment by the Participants. ("Participants" and other capitalized terms
defined in the Lease and used but not otherwise defined in this Amendment are
intended to have the meanings assigned to them in the Lease.) All Participants
have given such approval, as evidenced by their execution of the consents below.

        NOW, THEREFORE, in consideration of the mutual covenants provided herein
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, BNPLC and Chiron agree as follows:

2.Modifications to Ground Lease.    The Ground Lease is hereby modified and
amended as follows:

a.The expiration date of the Ground Lease Term (as defined in the Ground Lease)
is extended from December 31, 2030 to December 31, 2037.

b.The definition of Rent Commencement Date in Section 1(n) is amended and
restated as follows:

(n)Rent Commencement Date.    "Rent Commencement Date" means the earlier of
(1) the first Business Day of the first calendar month which is more than thirty
days after the Designated Sale Date and which is after the date upon which
Chiron and all subtenants or assignees of Chiron under the Lease have
relinquished possession of the Land and any part of the Improvements, or (2) the
first Business Day in July, 2009.

3.Modifications to List of Defined Terms.    The List of Defined Terms attached
to the Ground Lease, the Purchase Agreement and the Lease is hereby modified and
amended as follows:

a.The definition of Designated Sale Date is amended and restated as follows:

"Designated Sale Date" means the earlier of:

(1)any Business Day designated as such in a notice given by BNPLC to Chiron
after:

(A)an Event of Default or a breach by Chiron of any of the Purchase Documents
(and the expiration of any applicable cure or notice periods which may be
expressly provided in the Purchase Documents), including any breach by Chiron of
Paragraph 4 of the Purchase Agreement, which concerns Chiron's obligation to
deposit Restricted Funds if certain conditions specified in that Paragraph are
not satisfied; or

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(B)any failure of Chiron for any reason whatsoever (other than because of a
refusal by BNPLC to fund requested Construction Advances in breach of the Lease
or when, but for the condition specified in subparagraph of the Lease, such
refusal would constitute a breach of the Lease), on the date which is 120 days
before any Demand Deadline under the Guaranty, to have (1) caused the initial
Construction Project and any subsequent Construction Projects which are
commenced prior to such date to have been completed in a good and workmanlike
manner, substantially in accordance with Applicable Laws, and otherwise in
compliance with the provisions of (x) the Lease, (y) the Permitted Encumbrances
and (z) the Development Contracts, and (2) satisfied the conditions required to
obtain with respect to then existing Improvements any final certificates of
occupancy required for the use and occupancy thereof, a certificate of
compliance from the City of Emeryville and a certificate of completion from the
Redevelopment Agency as contemplated by the Development Contracts;

(2)any Business Day designated as such in an irrevocable, unconditional notice
given by Chiron to BNPLC; provided, the Business Day so designated by Chiron
must be no earlier than thirty days after the date of such notice, unless the
notice is given as contemplated in subparagraph of the Lease when an Event of
Default has occurred and is continuing, in which case the Business Date so
designated must be consistent with the requirements for an effective cure as
specified in subparagraph of the Lease; or

(3)the first Business Day of July 2009.

If BNPLC sends a notice to Chiron pursuant to the preceding clause (1) properly
designating a Designated Sale Date, and Chiron sends a notice to BNP pursuant to
the preceding clause (2) properly designating a different Designated Sale Date,
the earlier of the two dates so designated shall be the "Designated Sale Date"
hereunder regardless of which notice was first sent.

b.The definition of Demand Deadline is amended and restated as follows:

"Demand Deadline" means any date specified in the Guaranty as the date after
which no new demand for payment may be made upon the Guarantor pursuant to the
Guaranty. As of the Effective Date, the Demand Deadline is December 31, 2007.

c.After the date of this Amendment, no further Funding Advances shall be
required or permitted. As of the date of this Amendment, Funding Advances in the
amount of $173,330,000 have been made. The definition of Funding Advances is
amended and restated as follows:

"Funding Advances" means (1) the Initial Funding Advance and (2) all future
advances (which, together with Initial Funding Advance, are expected to total
but in no event exceed $173,330,000) made by BNPLC's Parent or any Participant
to or on behalf of BNPLC to allow BNPLC to provide the Construction Allowance
under the Lease.

d.The definition of Guaranty is amended and restated as follows:

"Guaranty" means the Guaranty dated June 30, 2003 given by Guarantor to BNPLC,
guarantying the obligations of Chiron under the Lease, the Purchase Agreement
and the Ground Lease until December 31, 2007, as such Guaranty may be extended,
supplemented, amended, restated or otherwise modified from time to time with the
consent of BNPLC.

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e.The definition of Guarantor is amended and restated as follows:

"Guarantor" means Novartis, AG, the largest shareholder of Chiron and the
successor of Ciba-Geigy, Ltd. through merger, and any successor of Novartis, AG
through merger.

f.The definition of LIBOR Period election is amended and restated as follows:

"LIBOR Period Election" for any Base Rent Period means a period of one month,
three months, or six months, as designated by Chiron at least ten Business Days
prior to the commencement of such Base Rent Period by a notice given to BNPLC in
the form of Exhibit attached to the Lease. (For purposes of the Lease a LIBOR
Period Election for any Base Rent Period shall also be considered the LIBOR
Period Election in effect on (1) the Base Rent Commencement Date or Base Rent
Date upon which such Base Rent Period begins and (2) subsequent Base Rent Dates,
if any, which occur before the date upon which such Base Rent Period ends.) Any
Libor Period Election so designated by Chiron shall remain in effect for the
entire Base Rent Period specified in Chiron's notice to BNPLC (provided such
Base Rent Period commences at least ten Business Days after BNPLC's receipt of
the notice) and for all subsequent Base Rent Periods until a new designation
becomes effective in accordance with the provisions set forth in this
definition. Notwithstanding the foregoing, however: (1) Chiron shall not be
entitled to designate a LIBOR Period Election that would cause a Base Rent
Period to extend beyond the end of the scheduled Term; (2) changes in the LIBOR
Period Election shall become effective only upon the commencement of a new Base
Rent Period; (3) for any Base Rent Period which will end on or after the first
Business Day in October, 1999, the only LIBOR Period Election permitted shall be
one month if for any reason whatsoever Chiron shall not, before such period
begins, have deposited all Restricted Funds required by Paragraph 4 of the
Purchase Agreement or otherwise entered into agreements with BNPLC which will
excuse Chiron's obligation to deposit Restricted Funds as contemplated by that
Paragraph; and (4) if Chiron fails to make a LIBOR Period Election consistent
with the foregoing requirements for any Base Rent Period, or if an Event of
Default shall have occurred and be continuing on the third Business Day
preceding the commencement of any Base Rent Period, the LIBOR Period Election
for such Base Rent Period shall be deemed to be one month.

g.The Maximum Construction Allowance has been fully and completely advanced, and
no further Construction Advances shall be required or permitted. The definition
of Maximum Construction Allowance is amended and restated as follows:

"Maximum Construction Allowance" means an amount equal to $173,330,000, less the
Initial Funding Advance.

h.The definition of Qualified Right to Stock Sale Proceeds is amended and
restated as follows:

"Qualified Right to Stock Sale Proceeds" means an unencumbered assignable
contractual right of Chiron, established by agreements in form and substance
satisfactory to each of BNPLC and the Participants in its sole and absolute
discretion, to receive from Guarantor no less than $184,000,000 in cash proceeds
from the issuance or sale of Chiron's stock to Guarantor. It is understood that
although agreements may exist between Chiron and Guarantor as of the Effective
Date which would obligate Guarantor to purchase Chiron's stock for more than
$184,000,000, such agreements have not been reviewed or approved by BNPLC or
Participants, and therefore prior to any such approval after the Effective Date,
such existing agreements cannot establish rights which would qualify under this
definition.

i.The definition of Residual Risk Percentage is amended and restated as follows:

"Residual Risk Percentage" means 10%.

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j.The definition of Spread is amended and restated as follows:

"Spread" means (1) on any date before construction of the initial Construction
Project is complete, 0.25% (twenty-five basis points), (2) on any date after
construction of the initial Construction Project is complete but prior to
July 1, 2003, 0.20% (twenty basis points), and (3) commencing on July 1, 2003
and thereafter, 0.40% (forty basis points).

For purposes of this definition, the initial Construction Project shall not be
deemed complete until Chiron shall have (1) caused the initial Construction
Project to have been completed in a good and workmanlike manner, substantially
in accordance with Applicable Laws, and otherwise in compliance with the
provisions of (x) the Lease, (y) the Permitted Encumbrances and (z) the
Development Contracts, and (2) obtained with respect to then existing
Improvements any final certificates of occupancy required for the use and
occupancy thereof, a certificate of compliance from the City of Emeryville and a
certificate of completion from the Redevelopment Agency as contemplated by the
Development Contracts.

k.The Stipulated Loss Value is agreed to be $173,330,000.

4.Modifications to Lease.    The Lease is hereby modified and amended as
follows:

a.The reference to "$195,000,000" on the first page is amended and restated to
refer to "$173,330,000".

b.The first sentence of Paragraph 1 is amended and restated as follows:

The term of this Lease (the "Term") shall commence on and include the Effective
Date, and end on July 1, 2009, unless sooner terminated as expressly herein
provided.

c.The Term may be extended at the option of Chiron for two successive periods of
five years each; provided, however, that prior to any such extension the
following conditions must have been satisfied: (A) at least 180 days prior to
the commencement of any such extension, BNPLC and Chiron must have agreed in
writing upon, and received the consent and approval of BNPLC's Parent and all
other Participants to (1) a corresponding extension not only to the date for the
expiration of the Term specified above, but also to the date specified in
clause (3) of the definition of Designated Sale Date, the Demand Deadline (and a
corresponding extension of the Guaranty), and (2) an adjustment to the Rent that
Chiron will be required to pay for the extension, it being expected that the
Rent for the extension may be different than the Rent required for the original
Term, and it being understood that the Rent for any extension must in all events
be satisfactory to BNPLC (and all Participants) and Chiron, in their sole and
absolute discretion; (B) no Event of Default shall have occurred and be
continuing at the time of Chiron's exercise of its option to extend;
(C) immediately prior to any such extension, the Lease, the Purchase Agreement,
the Ground Lease and the Guaranty must remain in effect. With respect to the
condition that BNPLC (and all Participants) and Chiron must have agreed upon the
Rent required for any extension of the Term, neither Chiron nor BNPLC (nor any
Participant) is willing to submit itself to a risk of liability or loss of
rights hereunder for being judged unreasonable. Accordingly, each of Chiron and
BNPLC (and each Participant) hereby disclaim any obligation express or implied
to be reasonable in negotiating the Rent for any such extension. Subject to the
changes to the Rent payable during any extension of the Term as provided in this
Paragraph, if Chiron exercises its option to extend the Term as provided in this
Paragraph, the Lease shall continue in full force and effect, and the leasehold
estate granted thereunder to Chiron shall continue without interruption and
without any loss of priority over other interests in or claims against the
Property that may be created or arise after the date hereof and before the
extension.

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d.Paragraph 4.(f) is amended and restated as follows:

(f)    Administrative Fees.    Upon execution and delivery of this Lease by
BNPLC, and again on each anniversary of the date hereof prior to the Designated
Sale Date, Chiron shall pay BNPLC an administrative fee (an "Administrative
Fee") as provided in the letter agreement dated May 15, 2003 between BNPLC and
Chiron. Each payment of an Administrative Fee shall represent Additional Rent
for the first Construction Period or Base Rent Period during which it first
becomes due.

e.Paragraph 10(a) is amended and restated as follows:

(a)    Liability Insurance.    Throughout the Term Chiron shall maintain
commercial general liability insurance against claims for bodily and personal
injury, death and property damage occurring in or upon or resulting from any
occurrence in or upon the Property, in standard form and with an insurance
company or companies reasonably acceptable to BNPLC (and so long as the Guaranty
specifies a Demand Deadline, then after the Demand Deadline BNPLC may reasonably
require that such insurance be provided through insurance or reinsurance
companies rated by the A.M. Best Company of Oldwick, New Jersey as having a
policyholder's rating of A- or better and a reported financial information
rating of VI or better), such insurance to afford immediate protection, to the
limit of not less than $50,000,000 combined single limit for bodily and personal
injury, death and property damage in respect of any one accident or occurrence,
with not more than $20,000,000 self-insured retention. Such commercial general
liability insurance shall include blanket contractual liability coverage which
insures contractual liability under the indemnifications set forth in this
Lease, but such coverage or the amount thereof shall in no way limit such
indemnifications. The policy evidencing such insurance shall name as additional
insureds BNPLC and all Participants of which Chiron has been notified (including
all of the Participants listed in Schedule). Chiron shall maintain with respect
to each policy or agreement evidencing such commercial general liability
insurance such endorsements as may be reasonably required by BNPLC and shall at
all times deliver and maintain with BNPLC written confirmation (in form
reasonably satisfactory to BNPLC) with respect to such insurance from the
applicable insurer or its authorized agent, which confirmation must provide that
insurance coverage will not be canceled or reduced without at least thirty days
notice to BNPLC. Not less than thirty days prior to the expiration date of each
policy of insurance required of Chiron pursuant to this subparagraph, Chiron
shall deliver to BNPLC a certificate evidencing a paid renewal policy or
policies.

f.Paragraph 10(b) is amended and restated as follows:

(b)    Property Insurance.    Throughout the Term Chiron will keep all
Improvements (including all alterations, additions and changes made to the
Improvements) which are located within the Property insured under an "all-risk"
property insurance policy (not excluding from coverage perils normally included
within the definitions of extended coverage, vandalism, malicious mischief and,
if the Property is in a flood zone, flood) in the amount no less than 100% of
the replacement value (exclusive of land, foundation, footings, excavations and
grading) with endorsements for contingent liability from operation of building
laws, increased cost of construction and demolition costs which may be necessary
to comply with building laws. Subject to the reasonable approval of BNPLC,
Chiron will be responsible for determining the amount of property insurance to
be maintained from time to time, but Chiron must maintain such coverage on an
agreed value basis to eliminate the effects of coinsurance. Such insurance must
be issued by an insurance company or companies reasonably acceptable to BNPLC,
and so long as the Guaranty specifies a Demand Deadline, then after the Demand
Deadline BNPLC may reasonably require that the insurance or reinsurance
companies providing such

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insurance be rated by the A.M. Best Company of Oldwick, New Jersey as having
(1) a policyholder's rating of A- or better, (2) a reported financial
information rating of no less than VI, and (3) in the case of each such company,
a reported financial information rating which indicates an adjusted
policyholders' surplus equal to or greater than the underwriting exposure that
such company has under the insurance or reinsurance it is providing for the
Property. Any deductible applicable to such insurance shall not exceed
$20,000,000. Such insurance shall cover not only the value of Chiron's interest
in the Improvements, but also the interest of BNPLC, and such insurance shall
include provisions that BNPLC must be notified at least thirty days prior to any
cancellation or reduction of insurance coverage. The policies under which Chiron
maintains such insurance may be "blanket" policies covering not only the
Property but other properties occupied or owned by Chiron; however, all policies
must provide that proceeds paid thereunder with respect to the Property will be
payable to BNPLC and Chiron as their interests may appear, it being understood
between BNPLC and Chiron that such proceeds shall be paid to BNPLC as Escrowed
Proceeds and will be applied in accordance with Paragraph 11 of this Lease. In
the event any of the Property is destroyed or damaged by fire, explosion,
windstorm, hail or by any other casualty against which insurance shall have been
required hereunder, (i) BNPLC may, but shall not be obligated to, make proof of
loss if not made promptly by Chiron after notice from BNPLC, (ii) each insurance
company concerned is hereby authorized and directed to make payment for such
loss directly to BNPLC for application as required by Paragraph 11, and
(iii) BNPLC may settle, adjust or compromise any and all claims for loss, damage
or destruction under any policy or policies of insurance (provided, that so long
as no Event of Default shall have occurred and be continuing, BNPLC must obtain
Chiron's consent to any such settlement, which consent will not be unreasonably
withheld). If any casualty shall result in damage to or loss or destruction of
the Property, Chiron shall give immediate notice thereof to BNPLC and
Paragraph 11 shall apply.

g.Paragraph 13(a)(iv) is amended and restated as follows:

(iv)    no more than 33% of the space in any completed Improvements shall be
subleased without BNPLC's prior consent to any Person that is neither (A) an
Affiliate of Chiron nor (B) the operator of a business in the subleased space
that is related to the operation of Chiron's own business.

h.The notice address of each of the parties referenced in
Paragraph 24(a)(iii) shall be as follows:

Address of BNPLC:

BNP Paribas Leasing Corporation
12201 Merit Drive, Suite 860
Dallas, Texas 75251
Attention: Lloyd G. Cox
Telecopy: (972) 788-9140

With a copy to:

BNP Paribas
One Front Street, 23rd Floor
San Francisco, California 94111
Attention: Katherine Wolfe
Telecopy: (415) 296-8954

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And with a copy to:

Clint Shouse
Thompson & Knight, LLP
1700 Pacific Avenue
Suite 3300
Dallas, Texas 75201
Telecopy: (214) 969-1751

Address of Chiron:

Chiron Corporation
Attn: Corporate Secretary
4560 Horton Street
Emeryville, CA 94608-2916
Telecopy: (510) 654-5360

With a copy to:

Chiron Corporation
Attn: Treasurer
4560 Horton Street
Emeryville, CA 94608-2916
Telecopy: (510) 601-3343

And with a copy to:

Paul, Hastings, Janofsky & Walker LLP
12390 El Camino Real
San Diego, CA 92130
Attention: Scott Biel
Telecopy: (858) 720-2555

5.Modifications to Purchase Agreement.    The Purchase Agreement is hereby
modified and amended as follows:

a.The reference to "$195,000,000" on the first page is amended and restated to
refer to "$173,330,000".

b.Paragraph 4 of the Purchase Agreement, prior to subparagraph 4(c) thereof, is
amended and restated as follows:

4.Security for Chiron's Obligations.    Chiron shall be excused from the
requirements set forth below in the various subparagraphs of this Paragraph 4,
if (but only if) on or prior to the first Business Day in September, 2007:
(1) Chiron shall have purchased or caused an Applicable Purchaser to have
purchased BNPLC's interest in the Property pursuant to subparagraph, and Chiron
shall have paid to BNPLC all amounts required in connection with the purchase;
or (2) Chiron shall have delivered to BNPLC a new amended and restated guarantee
by Guarantor (or by any surviving corporation that may result from a merger of
Guarantor with another Person) of the payment obligations of Chiron under the
Ground Lease, the Lease and this Agreement in the form attached hereto as
Exhibit J, expiring no earlier than September 30, 2009; or (3) Chiron shall have
obtained from BNPLC and all Participants a waiver in writing of the requirements
of this Paragraph 4 (it being understood that, if asked for such a waiver, BNPLC
or any of the Participants may in its sole and absolute discretion decline to
provide the waiver, as more

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particularly provided in subparagraph 4.(b) below). Unless Chiron is so excused,
Chiron shall comply with the following:

(a)Provisions for Financial Covenants or Security.    Chiron must do one (but
only one) of the following:

i.after satisfying the conditions set forth in subparagraph 4.(b), and no later
than the first Business Day of September, 2007, Chiron must execute and deliver
an amendment of this Agreement (the "Financial Covenant Amendment"), committing
Chiron to comply with financial covenants and pricing set forth therein; or

ii.after satisfying the conditions set forth in subparagraph 4.(c), and no later
than the first Business Day of September, 2007, Chiron must execute and deliver
Pledge Documents (as defined below) and thereby grant to BNPLC before a first
priority perfected security interest in Qualified Securities or in a Qualified
Right to Stock Sale Proceeds; or

iii.no later than the first Business Day of September, 2007, Chiron must deliver
immediately available funds to BNPLC in an amount equal to Stipulated Loss Value
("Restricted Funds"), which BNPLC shall be entitled to hold as security and
apply as hereinafter provided.

(b)Conditions to Chiron's Use of a Financial Covenant Amendment.    Before
Chiron may choose to satisfy the requirements of the preceding subparagraph
4(a)(i) by delivering a Financial Covenant Amendment (in lieu of Pledge
Documents or the delivery of Restricted Funds to BNPLC), the following condition
must be satisfied:

No later than ten Business Days prior to the first Business Day of September,
2007 Chiron must have received the prior approval of BNPLC and each of the
Participants of the form and substance of the Financial Covenant Amendment,
including the financial covenants and pricing provided therein that will be
incorporated into this Agreement and the Lease. The financial covenants and
pricing contained in the Financial Covenant Amendment shall be consistent with
financial covenants and pricing consistent with then market conditions for
similar quality credits (compared to Chiron) and remaining tenor to the Lease,
Ground Lease and Purchase Agreement. Neither BNPLC nor Participants shall,
however, be required to approve of any such amendment or of any financial
covenants or pricing therein proposed by Chiron before the same are in form and
substance satisfactory to each of BNPLC and the Participants in its sole and
absolute discretion. To facilitate Chiron's satisfaction of this condition,
BNPLC will cause its counsel to prepare and submit drafts of a Financial
Covenant Amendment, if Chiron requests such drafts from BNPLC in a notice given
to BNPLC and the Participants no later than June 1, 2007, and if Chiron
unconditionally confirms in such notice that Chiron will pay the Attorney's Fees
and any other reasonable costs incurred by BNPLC or the Participants in
connection with the preparation or approval of the drafts or otherwise incurred
in responding to the request.

c.In addition to the foregoing, all other requirements of Paragraph 4 are fully
and completely reinstated (notwithstanding the terms of Section 1 of the First
Amendment to Purchase Agreement dated September 1, 1999), and all other
references in Paragraph 4 to "September, 1999" are amended and restated to refer
to "September, 2007". The reference in Subparagraph 4.(c) to "June 1, 1999" is
amended and restated to refer to "June 1, 2007".

d.The notice address of each of the parties referenced in
Paragraph 10.(a)(iii) is modified to the same addresses given in the Lease (as
modified above).

e.Exhibit J is amended and restated with Exhibit J attached hereto.

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6.Legal Description.    The legal description of the Land attached to the Lease,
Ground Lease, and Purchase Agreement is amended and restated with the legal
description attached as Exhibit A hereto.

7.Fees.    Concurrently herewith, Chiron shall pay to BNPLC the following fees,
each of which are deemed fully earned by BNPLC and non-refundable to Chiron:

a.an upfront fee as provided in the letter agreement dated May 15, 2003 between
BNPLC and;

b.a best efforts arranger fee as provided in the letter agreement dated May 15,
2003 between BNPLC.

8.Representations and Covenants by BNPLC Concerning Accounting Matters.

a.BNPLC represents that to the knowledge of BNPLC the facts disclosed in the
financial statements and other documents listed in Exhibit B were (as of their
respective dates) true, correct and complete in all material respects. Copies of
those financial statements and documents were provided by or behalf of BNPLC to
Chiron prior to the date hereof to permit Chiron to determine the appropriate
accounting for Chiron's relationship with BNPLC under FASB Interpretation
No. 46, Consolidation of Variable Interest Entities ("FIN 46").

b.BNPLC also represents that to the knowledge of BNPLC the fair value of the
Property and of other properties, if any, leased to Chiron by BNPPLC
(collectively, whether one or more, the "Properties Leased to Chiron") are, as
of the date hereof, less than half of the total of the fair values of all assets
of BNPLC, excluding any assets of BNPLC which are held within a silo. Further,
BNPLC represents that none of the Properties Leased to Chiron are, as of the
date hereof, held within a silo. Consistent with the directions of Chiron (based
upon the current interpretation of FIN 46 by Chiron and its auditors), and for
purposes of this representation only:

!"held within a silo" means, with respect to any asset or group of assets leased
by BNPLC to a single lessee or group of affiliated lessees, that BNPLC has
obtained funds equal to or in excess of 95% of the fair value of the leased
asset or group of assets to acquire or maintain its investment in such asset or
group of assets through non-recourse financing or other contractual arrangements
(such as targeted equity or bank participations), the effect of which is to
leave such asset or group of assets (or proceeds thereof) as the only
significant asset or assets of BNPLC at risk for the repayment of such funds;

!"fair value" means, with respect to any asset, the amount for which the asset
could be bought or sold in a current transaction negotiated at arms length
between willing parties (that is, other than in a forced or liquidation sale);

!with respect to the Properties Leased by Chiron (regardless of how BNPLC
accounts for the leases of the Properties Leased by Chiron), and with respect to
other assets that are subject to leases accounted for by BNPLC as operating
leases pursuant to Financial Accounting Standards Board Statement 13 ("FAS 13"),
fair value is determined without regard to residual value guarantees,
remarketing agreements, non-recourse financings, purchase options or other
contractual arrangements, whether made by BNPLC with Chiron or with other
parties, that might otherwise impact the fair value of such assets;

!with respect to assets, other than Properties Leased by Chiron, that are
subject to leases accounted for by BNPLC as leveraged leases pursuant to FAS 13,
fair value is determined on a gross basis prior to the application of leveraged
lease accounting, recognizing that equity investments made by BNPLC in its
assets subject to leveraged lease accounting should be grossed up in applying
this test (however; equity investments made by BNPLC in another legal entity
should not be grossed up in applying this test);

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!with respect to assets, other than Properties Leased by Chiron, that are
subject to leases accounted for by BNPLC as direct financing leases pursuant to
FAS 13, fair value is determined as the sum of the fair values (considering
current interest rates at which similar loans would be made to borrowers with
similar credit ratings and for the same remaining maturities) of the
corresponding finance lease receivables and related unguaranteed residual
values.

c.BNPLC covenants that, as reasonably requested by Chiron from time to time with
respect to any accounting period during which the Lease is or was in effect,
BNPLC will provide to Chiron confirmation of facts concerning BNPLC and its
assets as reasonably necessary or appropriate to permit Chiron to determine the
proper accounting for the Lease (including updates of the facts set forth in the
documents provided to Chiron as described in clause a. above and of the facts
set forth in clause b. above, and including updates of the information described
on Exhibit B); except that BNPLC will not be required by this provision to
(x) provide any information that is not in the possession or control of BNPLC or
its Affiliates, (y) disclose the specific terms and conditions of its leases or
other transactions with other parties, or the names of such parties, or
(z) disclose any other information that is protected from disclosure by
confidentiality provisions in favor of such other parties or would be protected
if their agreements with BNPLC contained confidentiality provisions similar in
scope and substance to the confidentiality provisions set forth herein in favor
of Chiron and its Affiliates. BNPLC will represent that information provided by
it pursuant to this clause is true, correct and complete in all material
respects, but only to the knowledge of BNPLC as of the date it is provided,
utilizing the form of the certificate attached hereto as Exhibit C (signed by an
officer of BNPLC), which such certificate shall be provided by BNPLC five
business days before each of Chiron's fiscal quarter ends, or periodically
within five business days of reasonable written request therefor by Chiron as
provided above, or such longer period of time as may be reasonably necessary
under the circumstances in order for BNPLC to confirm such information.

d.Although the representations required of BNPLC by this subparagraph are
intended to cover facts, it is understood and agreed (consistent with
subparagraph 7(f) of the Lease) that BNPLC has not made and will not make any
representation or warranty as to the proper accounting by Chiron or its
Affiliates of the Lease or as to other accounting conclusions.

9.Reservation of Rights.    Chiron acknowledges and agrees that the execution
and delivery by BNPLC and the Participants of this Amendment shall not be deemed
to create a course of dealing or otherwise obligate BNPLC or the Participants to
enter into amendments under the same, similar or any other circumstances in the
future, except as otherwise provided in this Amendment and Paragraph 6 of the
Participation Agreement.

10.Successors and Assigns.    All of the covenants, agreements, terms and
conditions to be observed and performed by the parties hereto shall be
applicable to and binding upon their respective heirs, personal representatives,
successors and, to the extent assignment is permitted under the Lease, their
respective assigns.

11.Execution in Counterparts.    To facilitate execution, this Amendment may be
executed in as many identical counterparts as may be required. It shall not be
necessary that the signature of, or on behalf of, each party or consenting
party, or that the signature of all persons required to bind any party, appear
on each counterpart. All counterparts, taken together, shall collectively
constitute a single instrument. It shall not be necessary in making proof of
this Amendment to produce or account for more than a single counterpart
containing the respective signatures of, or on behalf of, each of the parties
and the consenting parties hereto. Any signature page to any counterpart may be
detached from such counterpart without impairing the legal effect of the
signatures thereon and

10

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thereafter attached to another counterpart identical thereto except having
attached to it additional signature pages. Signing and sending a counterpart (or
a signature page detached from the counterpart) by facsimile or other electronic
means to another party will have the same legal effect as signing and delivering
an original counterpart to the other party. A copy (including a copy produced by
facsimile or other electronic means) of any signature page that has been signed
by or on behalf of a party to this Amendment shall be as effective as the
original signature page for the purpose of proving such party's agreement to be
bound.

12.Miscellaneous.    Words of any gender used in the Lease, the Purchase
Agreement or the Ground Lease or any amendment to any of them, including this
Amendment itself (collectively, the "Operative Documents") shall be held and
construed to include any other gender, and words in the singular number shall be
held to include the plural and vice versa, unless the context otherwise
requires. References in any Operative Document to Paragraphs, subparagraphs,
Sections, subsections or other subdivisions shall refer to the corresponding
Paragraphs, subparagraphs, Sections, subsections or subdivisions of that
Operative Document, unless specific reference is made to another document or
instrument. References in any Operative Document to any Schedule or Exhibit
shall refer to the corresponding Schedule or Exhibit attached to that Operative
Document, which shall be made a part thereof by such reference. All capitalized
terms used in each Operative Document which refer to other documents shall be
deemed to refer to such other documents as they may be renewed, extended,
supplemented, amended or otherwise modified from time to time, provided such
documents are not renewed, extended or modified in breach of any provision
contained in the Operative Documents or, in the case of any other document to
which BNPLC is a party or of which BNPLC is an intended beneficiary, without the
consent of BNPLC. All accounting terms used but not specifically defined in any
Operative Document shall be construed in accordance with GAAP. The words "this
[Agreement]", "herein", "hereof", "hereby", "hereunder" and words of similar
import when used in each Operative Document refer to that Operative Document as
a whole and not to any particular subdivision unless expressly so limited. The
phrases "this Paragraph", "this subparagraph", "this Section", "this subsection"
and similar phrases used in any Operative Document refer only to the Paragraph,
subparagraph, Section, subsection or other subdivision described in which the
phrase occurs. As used in the Operative Documents the word "or" is not
exclusive. As used in the Operative Documents, the words "include", "including"
and similar terms shall be construed as if followed by "without limitation to".
The rule of ejusdem generis shall not be applied to limit the generality of a
term in any of the Operative Documents when followed by specific examples. When
used to qualify any representation or warranty made by a Person, the phrases "to
the knowledge of [such Person]" or "to the best knowledge of [such Person]" are
intended to mean only that such Person does not have knowledge of facts or
circumstances which make the representation or warranty false or misleading in
some material respect; such phrases are not intended to suggest that the Person
does indeed know the representation or warranty is true.

13.Disclosure.    BNPLC and each Participant (and each of their respective
officers, directors, employees, accountants, attorneys and other advisors,
agents and representatives) may disclose to any and all Persons, to the extent
required by applicable laws or as determined to be reasonably necessary by BNPLC
or any Participant to comply with applicable laws, upon written reasonable
request therefor (and following advance written notice to Chiron of BNPLC's or
such Participant's intent to make such disclosure), the U.S. tax treatment and
U.S. tax structure of the transactions contemplated hereby and such materials
(including opinions and other tax analyses) that are provided by third parties
to any of them relating to such U.S. tax treatment and U.S. tax structure, as
may be required to comply with applicable laws.

11

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[Signature pages follow.]

12

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        IN WITNESS WHEREOF, this Second Amendment has been executed as of
July 1, 2003.

 
   
   
    CHIRON CORPORATION +             By:   /s/  JOEL R. JUNG      

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    Printed Name: Joel R. Jung
Title: Vice President & Treasurer

13

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[Continuation of signature pages to Second Amendment dated to be effective as of
July 1, 2003]

 
   
   
    BNP PARIBAS LEASING CORPORATION,
a Delaware corporation
 
 
By:
 
/s/  LLOYD G. COX      

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    Printed Name: Lloyd G. Cox
Title: Managing Director

14

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[Continuation of signature pages to Second Amendment dated to be effective as of
July 1, 2003]

        The undersigned Participant hereby consents to the foregoing Amendment.

 
   
   
    BNP PARIBAS
 
 
By:
 
/s/  PIERRE NICHOLAS ROGERS      

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    Printed Name: Pierre Nicholas Rogers
Title: Managing Director
 
 
By:
 
/s/  RAFAEL C. LUMANIAN      

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    Printed Name: Rafael C. Lumanian
Title: Director

15

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[Continuation of signature pages to Second Amendment dated to be effective as of
July 1, 2003]

        The undersigned Participant hereby consents to the foregoing Amendment.

 
   
   
    CREDIT SUISSE FIRST BOSTON, CAYMAN ISLANDS BRANCH
 
 
By:
 
/s/  KARL M. STUDER      

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    Printed Name: Karl M. Studer
Title: Director
 
 
By:
 
/s/  BILL O'DALY      

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    Printed Name: Bill O'Daly
Title: Director

16

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[Continuation of signature pages to Second Amendment dated to be effective as of
July 1, 2003]

        The undersigned Participant hereby consents to the foregoing Amendment.

 
   
   
    UBS AG, Cayman Islands Branch     By:   /s/  WILFRED V. SAINT      

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    Printed Name: Wilfred V. Saint
Title: Associate Director
            Banking Products Services, US
 
 
By:
 
/s/  PATRICIA O'KICKI      

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    Printed Name: Patricia O'Kicki
Title: Director

17

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Exhibit A

Legal Description

REAL PROPERTY IN CITY OF EMERYVILLE, COUNTY OF ALAMEDA, STATE OF CALIFORNIA
DESCRIBED AS FOLLOWS:

LOT ONE:

"ADJUSTED LOT 1", AS DESCRIBED IN THE CERTIFICATE OF COMPLIANCE AND LOT LINE
ADJUSTMENT RECORDED FEBRUARY 1, 2002, SERIES NO. 2002051905, OFFICIAL RECORDS,
BEING ALL OF "RESULTING CHIRON LOT 1" AS SAID LOT IS DESCRIBED IN THE LOT LINE
ADJUSTMENT RECORDED NOVEMBER 13, 2001, SERIES NO. 2001441478, OFFICIAL RECORDS,
AND A PORTION OF LOT 2 AS SHOWN ON THE PARCEL MAP ENTITLED, "PARCEL MAP NO.
7032, CHIRON LIFE SCIENCES CENTER PHASE I", FILED SEPTEMBER 18, 1996 IN MAP BOOK
225, PAGES 35 THROUGH 37, ALAMEDA COUNTY RECORDS, MORE PARTICULARLY DESCRIBED AS
FOLLOWS:

ALL OF SAID "RESULTING CHIRON LOT 1" (2001441478);

AND A PORTION OF SAID LOT 2 (225 PM 35) MORE PARTICULARLY DESCRIBED AS FOLLOWS:

BEGINNING AT THE MOST WESTERN CORNER OF SAID LOT 2 (225 PM 35), THENCE ALONG THE
BOUNDARY OF SAID LOT 2 THE FOLLOWING FOUR COURSES:

I.NORTH 72°28'00" EAST 98.80 FEET; II.NORTH 17°32'00" WEST 55.00 FEET; III.NORTH
72°28'00" EAST 179.25 FEET; IV.SOUTH 27°46'45" EAST 177.83 FEET;

THENCE LEAVING THE BOUNDARY OF SAID LOT 2, SOUTH 72°28'00" WEST 106.08 FEET;
THENCE NORTH 17°32'00" WEST 22.00 FEET; THENCE SOUTH 72°28'00" WEST 203.60 FEET
TO A POINT ON THE BOUNDARY OF SAID LOT 2; THENCE ALONG THE BOUNDARY OF SAID LOT
2, NORTH 17°32'00" WEST 97.99 FEET TO THE POINT OF BEGINNING.

ASSESSOR'S PARCEL NO. 049-1041-070-02

LOT TWO:

"ADJUSTED LOT 2", AS DESCRIBED IN THE CERTIFICATE OF COMPLIANCE AND LOT LINE
ADJUSTMENT RECORDED FEBRUARY 1, 2002, SERIES NO. 2002051905, OFFICIAL RECORDS,
BEING A PORTION OF LOT 2 AS SHOWN ON THE PARCEL MAP ENTITLED, "PARCEL MAP NO.
7032, CHIRON LIFE SCIENCES CENTER PHASE I", FILED SEPTEMBER 18, 1996 IN MAP BOOK
225, PAGES 35 THROUGH 37, ALAMEDA COUNTY RECORDS, MORE PARTICULARLY DESCRIBED AS
FOLLOWS:

ALL OF SAID LOT 2 (225 PM 35) EXCEPTING THEREFROM THE FOLLOWING DESCRIBED
PARCEL:

BEGINNING AT THE MOST WESTERN CORNER OF SAID LOT 2 (225 PM 35), THENCE ALONG THE
BOUNDARY OF SAID LOT 2 THE FOLLOWING FOUR COURSES:

I.NORTH 72°28'00" EAST 98.80 FEET; 1NORTH 17°32'00" WEST 55.00 FEET; 2NORTH
72°28'00" EAST 179.25 FEET; 3SOUTH 27°46'45" EAST 177.83 FEET;

THENCE LEAVING THE BOUNDARY OF SAID LOT 2, SOUTH 72°28'00" WEST 106.08 FEET;
THENCE NORTH 17°32'00" WEST 22.00 FEET; THENCE SOUTH 72°28'00" WEST 203.60 FEET
TO A POINT ON THE BOUNDARY OF SAID LOT 2; THENCE ALONG THE BOUNDARY OF SAID LOT
2, NORTH 17°32'00" WEST 97.99 FEET TO THE POINT OF BEGINNING.

ASSESSOR'S PARCEL NO. 049-1041-071-02

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Exhibit B

A.Unaudited balance sheet of BNPPLC dated April 30, 2003.

B.Unaudited income statement of BNPPLC dated April 30, 2003.

C.Portfolio listing dated April 30, 2003, listing individual lease transactions
by origination date, expiration date, lease balance, share held by BNPPLC or its
Affiliates and share held by third party participants.

D.RAROC model of BNPPLC's portfolio as of April 30, 2003, run under several sets
of assumptions.

E.Memorandum dated March 10, 2003 to Lloyd Cox from Clint Shouse, summarizing
features of BNPPLC's in the participation structure, including the earlier
memorandum attached thereto to Lloyd Cox from Clint Shouse dated February 12,
2003.

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Exhibit C

Form of Certificate

Chiron Corporation
4560 Horton Street
Emeryville, California 94608-2916

Gentlemen:

        This Certificate is furnished pursuant to that certain Lease Agreement
dated as of June 28, 1996 (as amended, the "Lease") and that certain Second
Amendment dated as of July 1, 2003 (the "Second Amendment"), the terms defined
in the Lease and Second Amendment being used herein as therein defined. The
undersigned, as                        of BNP Paribas Leasing Corporation
("BNPLC"), does hereby certify that the following are true, correct and complete
in all material respects, but only to the knowledge of BNPLC as of the date
hereof:

1.BNPLC represents that to the knowledge of BNPLC the facts disclosed in the
financial statements and other documents listed in Exhibit attached hereto were
(as of their respective dates) true, correct and complete in all material
respects. Copies of those financial statements and documents were provided by or
behalf of BNPLC to Chiron prior to the date hereof to permit Chiron to determine
the appropriate accounting for Chiron's relationship with BNPLC under FASB
Interpretation No. 46, Consolidation of Variable Interest Entities ("FIN 46").

2.BNPLC also represents that to the knowledge of BNPLC the fair value of the
Property and of other properties, if any, leased to Chiron by BNPPLC
(collectively, whether one or more, the "Properties Leased to Chiron") are, as
of the date hereof, less than half of the total of the fair values of all assets
of BNPLC, excluding any assets of BNPLC which are held within a silo. Further,
BNPLC represents that none of the Properties Leased to Chiron are, as of the
date hereof, held within a silo.

        Although the representations required of BNPLC by this certificate are
intended to cover facts, it is understood and agreed (consistent with
subparagraph 7(f) of the Lease) that BNPLC has not made and will not make any
representation or warranty as to the proper accounting by Chiron or its
Affiliates of the Lease or as to other accounting conclusions.

        Executed this            day of                        , 20    .

 
   
   
   
    BNP Paribas Leasing Corporation
 
 
By:
 
 
 
         

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        Name:                

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        Title:                

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Exhibit J

Form of Replacement Guaranty of Novartis, AG

GUARANTY

        This Guaranty is made effective as of July 1, 2003 by Novartis, AG (the
"Guarantor") in favor of BNP Paribas Leasing Corporation, a Delaware
corporation, which is wholly owned by BNP Paribas ("BNPLC"), and in favor of BNP
Paribas, Credit Suisse First Boston, UBS AG, Cayman Islands Branch and any other
banks or financial institutions that become "Participants" with BNPLC (as
defined in the Lease). BNPLC and such Participants are sometimes hereinafter
referred to collectively as the "Banks".

        WHEREAS,

        At the request of Chiron Corporation, a Delaware corporation ("Chiron"),
in which the Guarantor is a major shareholder, BNPLC has advanced funds to
Chiron pursuant to the "Lease and Purchase Agreements" (as defined hereinafter),
and BNPLC and the Participants have agreed to make certain modifications to the
Lease and Purchase Agreements pursuant to the Second Amendment of even date
herewith (the "Amendment"), and

        WHEREAS,

        it is a condition of BNPLC and the Participants to their execution of
the Amendment, that the Guarantor guarantee the obligations of Chiron under the
Lease and Purchase Agreements,

        NOW, THIS GUARANTY WITNESSES as follows:

1.Guaranty.    The Guarantor irrevocably and unconditionally undertakes to
secure to BNPLC the due and punctual payment of all money that may become due
from time to time to BNPLC from Chiron under or as provided in the following
documents, as amended from time to time (the "Lease and Purchase Agreements"):

(a)the Ground Lease dated as of June 28, 1996 (but effective as of July 1,
1996), providing (among other things) for the sublease by Chiron to BNPLC of
land described therein (the "Land");

(b)the Lease Agreement dated as of June 28, 1996 (but effective as of July 1,
1996), providing (among other things) for the construction of improvements on
the Land by Chiron with funds advanced by BNPLC (which such construction has
been completed) and the use and sublease by Chiron from BNPLC of the Land and
the improvements (the "Lease"); and

(c)the Purchase Agreement dated as of June 28, 1996 (but effective as of July 1,
1996), providing (among other things) for the sale by BNPLC of Land and
improvements thereon to Chiron or to a third party designated by Chiron (the
"Purchase Agreement").

        The Guarantor therefore undertakes to pay on first demand of BNPLC any
amount payable under or as provided in the Lease and Purchase Agreements up to a
maximum total amount (the "Maximum Amount") of USD $173,330,000 irrespective of
the validity and the legal effects of the Lease and Purchase Agreements, waiving
all rights of objection and defense arising therefrom upon receipt of the
written request for payment and the statement in writing by BNPLC that Chiron
has not made payment on the date(s) specified and the amount called under the
Guaranty.

2.BNPLC's Obligation to Distribute Payments to Participants:    Guarantor has
been advised that the following agreements (the "Participation Agreements")
establish the respective rights and obligations of the Banks concerning advances
of funds to Chiron required by the Lease and

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Purchase Agreements and concerning the allocation among the Banks of payments
required of Chiron by the Lease and Purchase Agreements:

(a)the Participation Agreement between BNPLC and BNP Paribas (as successor in
interest to Banque Nationale de Paris) dated as of June 28, 1996 (but effective
as of July 1, 1996), providing (among other things) for (1) the advance by BNP
Paribas of a percentage ("BNP Paribas' Percentage") of the funds that Chiron may
request from BNPLC under the Lease and Purchase Agreements and (2) the payment
to BNP Paribas of BNP Paribas' Percentage of certain payments received by BNPLC
from Chiron under the Lease and Purchase Agreements;

(b)the Participation Agreement between BNPLC and Credit Suisse First Boston (as
successor in interest to Credit Suisse) dated as of June 28, 1996 (but effective
as of July 1, 1996), providing (among other things) for (1) the advance by
Credit Suisse First Boston, Cayman Islands Branch of a percentage ("Credit
Suisse's Percentage") of the funds that Chiron may request from BNPLC under the
Lease and Purchase Agreements and (2) the payment to Credit Suisse of Credit
Suisse's Percentage of certain payments received by BNPLC from Chiron under the
Lease and Purchase Agreements; and

(c)the Participation Agreement between BNPLC and UBS AG, Cayman Islands Branch
(as successor in interest to Union Bank of Switzerland) dated as of June 28,
1996 (but effective as of July 1, 1996), providing (among other things) for
(1) the advance by UBS AG, Cayman Islands Branch of a percentage ("UBS AG's
Percentage") of the funds that Chiron may request from BNPLC under the Lease and
Purchase Agreements and (2) the payment to UBS AG, Cayman Islands Branch of UBS
AG's Percentage of certain payments received by BNPLC from Chiron under the
Lease and Purchase Agreements.

        Except as provided in the next paragraph, any demand for payment made by
BNPLC upon Guarantor under this Guaranty will constitute a demand made not only
for BNPLC itself, but also on behalf of Participants. Further, if BNPLC does
make such a demand for itself and for Participants, BNPLC shall distribute a
portion of any payments BNPLC receives from Guarantor to Participants in
accordance with the Participation Agreements, and BNPLC shall also distribute a
portion of any payments BNPLC receives from Guarantor to Participants in
accordance with the Participation Agreements.

3.Separate Demands by BNPLC and Participants:    If Chiron shall fail to pay an
amount for which BNPLC can demand payment from Guarantor under this Guaranty,
the Banks may agree among themselves to each make a separate demand directly
upon Guarantor. However, to be effective for purposes of this Guaranty, any such
agreement by the Banks must be in writing; must be provided to Guarantor before
BNPLC makes a demand upon Guarantor for itself and for Participants; and must
specify the respective amounts that BNPLC and each Participant will for itself
demand of Guarantor. Also, the total of all amounts specified in any such
agreement as amounts that will be demanded of Guarantor must not exceed (before
any addition required by the next paragraph) Guarantor's maximum liability. If
Guarantor receives an agreement among the Banks that satisfies the requirements
set forth in the preceding sentences, Guarantor shall honor any separate demands
made by BNPLC and Participants in accordance with such agreement by making
payments directly to BNPLC and Participants, rather than by making a single
payment to BNPLC.

4.Gross Up:    Subject to the understanding that Guarantor's liability will not
exceed (except as provided in the next sentence) the Maximum Amount, Guarantor
hereby expressly undertakes and secures that payments under this Guaranty will
not be less than as stipulated in the Lease and Purchase Agreements. In
implementation of this undertaking and in case Swiss withholding taxes are
imposed in respect of payments made under this Guaranty, the Guarantor
undertakes, as a separate and independent obligation, irrespective of the
Maximum Amount, to pay additional amounts equal to such withholding taxes so
that the net payments

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received by BNPLC shall equal the amount actually owed by Chiron to BNPLC under
the Lease and Purchase Agreements.

5.Guarantor's Obligations Continuing:    The Guarantor's obligations under this
Guaranty are and will remain in full force and effect by way of continuing
security until no sum remains payable under the Lease and Purchase Agreements.
Furthermore, these obligations of the Guarantor are additional to, and not
instead of, any security or other guarantee or indemnity at any time existing in
favor of BNPLC, whether from the Guarantor or otherwise. The Guarantor
irrevocably waives all notices and demands whatsoever. However, Guarantor shall
not have to make any payment requested for the first time after December 31,
2009 by BNPLC (as provided in the last sentence of Paragraph 1) or by BNPLC or
Participants (as provided in accordance with an agreement described in
Paragraph 3).

6.Repayments in Liquidation:    If any payment received by BNPLC or payable to
BNPLC under the Lease and Purchase Agreements is, on the liquidation or
insolvency of Chiron, excused, reduced or avoided under any laws relating to
liquidation or insolvency, such payment or the excuse, reduction or avoidance of
such payment will not be considered as having discharged or diminished the
liability of the Guarantor and this Guaranty will continue to apply as if such
payment had at all times remained owning by Chiron.

7.Status of Guaranty:    The payment obligations of the Guarantor under this
Guaranty constitute direct, unconditional and unsecured obligations of the
Guarantor and rank and will rank pari passu with all other outstanding unsecured
and unsubordinated indebtedness and monetary obligations of the Guarantor,
present or future, including those in respect of deposits, but, in the event of
insolvency, bankruptcy, reorganization or similar proceedings, only to the
extent permitted by applicable laws to creditors' rights.

8.Power to Execute:    The Guarantor hereby warrants, represents and covenants
that it has all corporate power, and has taken all necessary corporate or other
steps, to enable it to execute, deliver and perform this Guaranty, and that this
Guaranty constitutes a legal, valid and binding obligation of the Guarantor in
accordance with its terms.

9.Transfer of Rights:    If and to the extent the Guarantor has made payment
under the Guaranty the Guarantor is entitled to the transfer of BNPLC's rights
against Chiron and the right of recovery from Chiron. However, the Guarantor
shall not by virtue of this Guaranty be entitled to the transfer of any rights
of BNPLC or claim in competition with BNPLC until all amounts which may be
payable under the Lease and Purchase Agreements have been paid in full.

10.Governing Law and Jurisdiction:    This Guaranty is governed by and shall be
construed in accordance with Swiss law. Exclusive jurisdiction and venue for any
legal proceeding brought to enforce this Guaranty will be in Basle, Switzerland.
This present Guaranty supersedes the one issued by Novartis, AG,
Basel/Switzerland on August 31, 1999 amounting to USD $172,572,542.12, which
will be returned to Novartis, AG.

 
   
   
    NOVARTIS, AG
 
 
By:
 
         

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QuickLinks

Exhibit 10.004

SECOND AMENDMENT
Exhibit A Legal Description
Exhibit B
Exhibit C Form of Certificate
Exhibit J Form of Replacement Guaranty of Novartis, AG GUARANTY