Document:

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                                                                     EXHIBIT 4.1

                              SCHEDULE 1.6(a)(iii)

                                  PROXIM, INC.
                          REGISTRATION RIGHTS AGREEMENT

     This Registration Rights Agreement (this "Agreement") is made and entered
into as of September 27, 2000 by and between Proxim, Inc., a Delaware
corporation (the "Company"), and Siemens Aktiengesellschaft, a German
corporation ("Siemens AG"), and Siemens Information and Communication Mobile
LLC, a Delaware limited liability company ("Siemens ICM" and together with
Siemens AG, the "Stockholders").

                                    RECITALS

     WHEREAS, the Company and the Stockholders have entered into an Asset
Purchase Agreement (the "Asset Purchase Agreement") dated as of September 27,
2000 pursuant to which, among other things, the Company has purchased certain
assets and assumed certain liabilities of the Stockholders, all as fully set
forth and described in the Asset Purchase Agreement. Unless otherwise provided
herein, all capitalized terms shall have the meanings set forth in the Asset
Purchase Agreement.

     WHEREAS, the Asset Purchase Agreement provides that the Stockholders shall
be granted certain registration rights and other rights, all as more fully set
forth herein.

     NOW, THEREFORE, in consideration of the foregoing recitals, the mutual
promises hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

     1.   REGISTRATION RIGHTS

          (a)  Definitions. For purposes of this Section 1:

               (i)  Registration. The terms "register," "registered," and
"registration" refer to a registration effected by preparing and filing a
registration statement in compliance with the Securities Act of 1933, as
amended, (the "Securities Act"), and the declaration or ordering of
effectiveness of such registration statement

               (ii) Registrable Securities. The term "Registrable Securities"
means: (x) 500,000 shares of Common Stock of the Company acquired by the
Stockholders from the Company pursuant to the Asset Purchase Agreement (the
"Acquired Shares"); and (y) any shares of Common Stock of the Company or other
securities of the Company issued as (or issuable upon the conversion or exercise
of any warrant, right or other security that is issued as) a dividend or other
distribution with respect to, or in exchange for or in replacement of, any of
the securities described in the immediately preceding clause (x) or (y).
Notwithstanding the foregoing, "Registrable Securities" shall exclude any
Registrable Securities sold by a person in a transaction in which rights under
this Section 1 are not assigned in accordance with this Agreement or any
Registrable Securities sold in a public offering, whether sold pursuant to Rule
144 promulgated under the Securities Act, or in a registered offering, or
otherwise.

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               (iii) Registrable Securities Then Outstanding. The number of
shares of "Registrable Securities then outstanding" shall mean the number of
shares of Acquired Shares, shares of Common Stock and other securities that are
Registrable Securities and are then issued and outstanding.

               (iv) Holder. For purposes of this Section 1, the term "Holder"
means Stockholders or any subsidiary or affiliate of Stockholders owning of
record Registrable Securities that have not been sold to the public or pursuant
to Rule 144 promulgated under the Securities Act or any permitted assignee of
record of such Registrable Securities to whom rights under this Section 1 have
been duly assigned in accordance with Section 4 of this Agreement.

               (v)  Form S-3. The term "Form S-3" means such form under the
Securities Act as is in effect on the date hereof or any successor registration
form under the Securities Act subsequently adopted by the SEC that permits
inclusion or incorporation of substantial information by reference to other
documents filed by the Company with the SEC.

          (b)  Demand Registration.

               (i)  Request by Holders. If, at any time following the first
anniversary of the Closing Date, as defined in the Asset Purchase Agreement,
during which the Company is not eligible to file a registration statement on
Form S-3, the Company receives a written request from Holders with respect to
not less than twenty-five percent (25%) of the Acquired Shares issued as of the
Closing Date that the Company file a registration statement under the Securities
Act on Form S-1 or such other form as such Holders may request covering the
registration of Registrable Securities, then the Company shall, within ten (10)
business days of the receipt of such written request, give written notice of
such request ("Request Notice") to all Holders, and use commercially reasonable
efforts to effect, as soon as practicable, the registration under the Securities
Act of all Registrable Securities that Holders request to be registered and
included in such registration by written notice given by such Holders to the
Company within twenty (20) days after receipt of the Request Notice; provided
that the Company shall not be obligated to effect any such registration if the
Company has, within the six (6) month period preceding the date of such request,
already effected a registration under the Securities Act pursuant to this
Section 1(b) or Section 1(c) or (d), other than a registration from which the
Registrable Securities of Holders have been excluded with respect to all or any
portion of the Registrable Securities the Holders requested be included in such
registration; provided, further, that the Company shall have no obligation to
file any registration statement contemplated by this Section 1(b) if the
expected gross proceeds of the sale of Registrable Securities under such
registration statement, based on the market price of the Common Stock as of the
date of the initial request for such registration delivered by the Holders, does
not exceed Three Million Dollars ($3,000,000). If requested by such Holders, the
Company shall register such Registrable Securities on Form S-1 or any successor
registration form.

               (ii) Underwriting. If the Holders initiating the registration
request under this Section 1(b) ("Initiating Holders") intend to distribute the
Registrable Securities covered by their request by means of an underwriting,
then they shall so advise the Company as a part of their request, and the
Company shall include such information in the written notice referred to in
Section 1(b)(i). In such event, the right of any Holder to include its
Registrable

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Securities in such registration shall be conditioned upon such Holder's
participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting (unless otherwise mutually agreed by
a majority in interest of the initiating Holders and such Holder determined
based on the number of Registrable Securities held by such Holders being
registered). All Holders proposing to distribute their securities through such
underwriting shall enter into an underwriting agreement in customary form with
the managing underwriter or underwriters selected for such underwriting by the
Holders of a majority of the Registrable Securities being registered and
reasonably acceptable to the Company (including a market stand-off agreement of
up to 180 days if required by such underwriters). Notwithstanding any other
provision of this Section 1(b), if the underwriter(s) advise(s) the Company in
writing that marketing factors require a limitation of the number of securities
to be underwritten then the Company shall so advise all Holders of Registrable
Securities that would otherwise be registered and underwritten pursuant hereto,
and the number of Registrable Securities that may be included in the
underwriting shall be reduced as required by the underwriter(s) and allocated
among the Holders of Registrable Securities on a pro rata basis according to the
number of Registrable Securities then outstanding held by each Holder requesting
registration (including the initiating Holders); provided, however, that the
number of shares of Registrable Securities to be included in such underwriting
and registration shall not be reduced unless all other securities of the Company
and any selling securityholder other than the Holders are first entirely
excluded from the underwriting and registration. Any Registrable Securities
excluded and withdrawn from such underwriting shall be withdrawn from the
registration.

               (iii) Maximum Number of Demand Registrations. The Company shall
be obligated to effect only three (3) such registrations pursuant to this
Section 1(b).

               (iv) Deferral. Notwithstanding the foregoing, if the Company
shall furnish to Holders requesting the filing of a registration statement
pursuant to this Section 1(b), a certificate signed by the Chief Executive
Officer of the Company stating that in the good faith judgment of the Board, it
would be materially detrimental to the Company and its stockholders for such
registration statement to be filed, then the Company shall have the right to
defer such filing for a period of not more than ninety (90) days after receipt
of the request of the initiating Holders; provided, however, that the Company
may not utilize this right more than once in any twelve (12) month period.

               (v)  Expenses. All expenses incurred in connection with any
registration pursuant to this Section 1(b), including all federal and "blue sky"
registration, filing and qualification fees, printer's and accounting fees, and
fees and disbursements of counsel for the Company (but excluding underwriters'
discounts and commissions relating to shares sold by the Holders and any fees
and disbursements of counsel to the Holders), shall be borne by the Company.
Each Holder participating in a registration pursuant to this Section 1(b) shall
bear such Holder's proportionate share (based on the total number of shares sold
in such registration other than for the account of the Company) of all
discounts, commissions or other amounts payable to underwriters or brokers in
connection with such offering by the Holders. Notwithstanding the foregoing, the
Company shall not be required to pay for any expenses of any registration
proceeding begun pursuant to this Section 1(b) if the registration request is
subsequently withdrawn at the request of the Holders of a majority of the
Registrable Securities to be registered, unless the Holders of such majority
agree that such registration constitutes the

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use by the Holders of one (1) demand registration pursuant to this Section 1(b)
(in which case such registration shall also constitute the use by all Holders of
Registrable Securities of one (l) such demand registration); provided further,
however, that if at the time of such withdrawal, the Holders have learned of a
material adverse change relating to the business or operations of the Company
not known to the Holders at the time of their request for such registration and
have withdrawn their request for registration after learning of such material
adverse change, then the Holders shall not be required to pay any of such
expenses and such registration shall not constitute the use of a demand
registration pursuant to this Section 1(b).

          (c)  Piggyback Registrations. Following the first anniversary of the
Closing Date, as defined in the Asset Purchase Agreement, the Company shall
notify all Holders of Registrable Securities in writing at least twenty (20)
days prior to filing any registration statement under the Securities Act for
purposes of effecting a public offering of securities of the Company (including
registration statements relating to secondary offerings of securities of the
Company, but excluding registration statements relating to any employee benefit
plan or any merger or other corporate reorganization) and will afford each such
Holder an opportunity to include in such registration statement all or any part
of the Registrable Securities then held by such Holder. Each Holder desiring to
include in any such registration statement all or any part of the Registrable
Securities held by such Holder shall within twenty (20) days after receipt of
the above-described notice from the Company, so notify the Company in writing,
and in such notice shall inform the Company of the number of Registrable
Securities such Holder wishes to include in such registration statement. If a
Holder decides not to include all of its Registrable Securities in any
registration statement thereafter filed by the Company, such Holder shall
nevertheless continue to have the right to include any Registrable Securities in
any subsequent registration statement or registration statements as may be filed
by the Company with respect to offerings of its securities, all upon the terms
and conditions set forth herein.

               (i)  Underwriting. If a registration statement under which the
Company gives notice under this Section 1(c) is for an underwritten offering,
then the Company shall so advise the Holders of Registrable Securities. In such
event, the right of any such Holder's Registrable Securities to be included in
such a registration pursuant shall be conditioned upon such Holder's
participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their Registrable Securities through such
underwriting shall enter into an underwriting agreement in customary form with
the managing underwriter or underwriters selected for such underwriting
(including a market stand-off agreement of up to 180 days if required by such
underwriters); provided, however, that it shall not be considered customary to
require any of the Holders to provide representations and warranties regarding
the Company or indemnification of the underwriters for material misstatements or
omissions in the registration statement or prospectus for such offering.
Notwithstanding any other provision of this Agreement, if the managing
underwriter determine(s) in good faith that marketing factors require a
limitation of the number of shares to be underwritten, then the managing
underwriter(s) may exclude shares from the registration and the underwriting;
provided; however, that the securities to be included in the registration and
the underwriting shall be allocated, (A) first to the Company (provided,
however, that a minimum of fifteen percent (15%) of the number of Registrable
Securities that each Holder (where any Registrable Securities that are not
shares of Common Stock but are exercisable or exchangeable for, or convertible
into, shares of Common Stock, shall be deemed

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to have been so exercised, exchanged or converted for such purpose) must also in
any event be included), (B) second, to the extent the managing underwriter
determines additional securities can be included after compliance with Clause
(A), to each of the Holders (to the extent not included pursuant to Clause (A))
requesting inclusion of their Registrable Securities in such registration
statement on a pro rata basis based on the total number of Registrable
Securities and other securities entitled to registration then held by each such
Holder, and (C) third, to the extent the managing underwriter determines
additional securities can be included after compliance with Clauses (A) and (B),
any other shares of Common Stock or other securities of the Company. Any
Registrable Securities excluded or withdrawn from such underwriting shall be
excluded and withdrawn from the registration. For any Holder that is a
partnership, the Holder and the partners and retired partners of such Holder, or
the estates and family members of any such partners and retired partners and any
trusts for the benefit of any of the foregoing persons, and for any Holder that
is a corporation, the Holder and all corporations that are affiliates of such
Holder, shall be deemed to be a single "Holder," and any pro rata reduction with
respect to such "Holder" shall be based upon the aggregate amount of shares
carrying registration rights owned by all entities and individuals included in
such "Holder," as defined in this sentence.

               (ii) Expenses. All expenses incurred in connection with a
registration pursuant to this Section 1(c) (excluding underwriters' and brokers'
discounts and commissions relating to shares sold by the Holders and any fees
and disbursements of counsel to the Holders), including all federal and "blue
sky" registration, filing and qualification fees, printers' and accounting fees,
and fees and disbursements of counsel for the Company, shall be borne by the
Company.

               (iii) Not Demand Registration. Registration pursuant to this
Section 1(c) shall not be deemed to be a demand registration as described in
Section 1(b) above. Except as otherwise provided herein, there shall be no limit
on the number of times the Holders may request registration of Registrable
Securities under this Section 1(c).

          (d)  Form S-3 Registration. If, at any time after the first
anniversary of the Closing Date, as defined in the Asset Purchase Agreement, the
Company is so requested by any Holder, the Company shall use all reasonable
commercial efforts to cause to be filed and become effective with the SEC a
registration statement on Form S-3, if available, relating to all of the
Registrable Securities; provided, however, that the Company shall have no
obligation to file any registration statement contemplated by this Section 1(d)
if the expected gross proceeds of the sale of Registrable Securities under such
registration statement, based on the market price of the Common Stock as of the
date of such request, does not exceed Three Million Dollars ($3,000,000). The
Company shall use commercially reasonable efforts to cause any such registration
statement to become effective as promptly as practicable after such filing and
shall also use commercially reasonable efforts to obtain any related
qualifications, registrations or other compliances that may be necessary under
any applicable "blue sky" laws. In connection with such registration, the
Company will:

               (i)  Notice. Promptly give written notice to the Holders of the
proposed registration and any related qualification or compliance; and

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               (ii) Registration. Effect such registration and all such
qualifications and compliances and as would permit or facilitate the sale and
distribution of all or such portion of such Holders or Holders' Registrable
Securities; provided, however, that the Company shall not be obligated to effect
any such registration, qualification or compliance pursuant to this Section 1(d)
in any particular jurisdiction in which the Company would be required to qualify
to do business or to execute a general consent to service of process in
effecting such registration, qualification or compliance.

               (iii) Number of Form S-3 Registrations. The Company shall be
obligated to effect only three (3) registrations upon the request of the Holders
under this Section 1(d).

               (iv) Expenses. The Company shall pay all expenses incurred in
connection with each registration requested pursuant to this Section 1(d),
excluding underwriters' or brokers' discounts and commissions relating to shares
sold by the Holders and any fees and disbursements of counsel to the Holders,
but including federal and "blue sky" registration, filing and qualification
fees, printers' and accounting fees, and fees and disbursements of counsel.

               (v)  Deferral. Notwithstanding the foregoing, if the Company
shall furnish to Holders requesting the filing of a registration statement
pursuant to this Section 1(d), a certificate signed by the Chief Executive
Officer of the Company stating that in the good faith judgment of the Board, it
would be materially detrimental to the Company and its stockholders for such
registration statement to be filed, then the Company shall have the right to
defer such filing for a period of not more than ninety (90) days after receipt
of the request of the initiating Holders; provided, however, that the Company
may not utilize this right more than once in any twelve (12) month period, and
the period of time that the Company is obligated to maintain the effectiveness
of any registration statement under Clause (vii) below shall be extended for the
length of any such period of deferral.

               (vi) Not Demand Registration. Form S-3 registrations shall not be
deemed to be demand registrations as described in Section 1(b) above.

               (vii) Maintenance. The Company shall use all reasonable
commercial efforts to maintain the effectiveness of any Form S-3 registration
statement filed under this Section 1(d) until the earlier of: (a) the date on
which all of the Registrable Securities have been sold; and (b) sixty (60) days
after the effective date of such registration statement; provided, however, that
unless all of the Registrable Securities held by the Holders as of such
anniversary date could then be sold in a single transaction in accordance with
Rule 144 under the Securities Act without exceeding the volume limitations
thereof, if the Company receives written notice from the Holders that the
Holders may be deemed to be "affiliates" of the Company for purposes of the
Securities Act, the date in this Clause (b) shall be extended until the Holders
advise the Company that they no longer believe it may be deemed such an
"affiliate."

          (e)  Obligations of the Company. Whenever required to effect the
registration of any Registrable Securities under this Agreement the Company
shall, as expeditiously as reasonably possible:

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               (i)  Registration Statement. Prepare and file with the SEC a
registration statement with respect to such Registrable Securities and use
commercially reasonable efforts to cause such registration statement to become
effective; provided, however, that, except as otherwise required in this Section
1, the Company shall not be required to keep any such registration statement
effective for more than sixty (60) days.

               (ii) Amendments and Supplements. Prepare and file with the SEC
such amendments and supplements to such registration statement and the
prospectus used in connection with such registration statement as may be
necessary to comply with the provisions of the Securities Act with respect to
the disposition of all securities covered by such registration statement.

               (iii) Prospectuses. Furnish to the Holders such number of copies
of a prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may
reasonably request in order to facilitate the disposition of the Registrable
Securities owned by them that are included in such registration.

               (iv) Blue Sky. Use commercially reasonable efforts to register
and qualify the securities covered by such registration statement under such
other securities or Blue Sky laws of such jurisdictions as shall be reasonably
requested by the Holders, provided that the Company shall not be required in
connection therewith or as a condition thereto to qualify to do business or to
file a general consent to service of process in any such states or
jurisdictions.

               (v)  Underwriting. In the event of any underwritten public
offering, enter into and perform its obligations under an underwriting agreement
in usual and customary form (including customary indemnification of the
underwriters by the Company), with the managing underwriter(s) of such offering.
Each Holder participating in such underwriting shall also enter into and perform
its obligations under such an agreement; provided, however, that it shall not be
considered customary to require any of the Holders to provide representations
and warranties regarding the Company or indemnification of the underwriters for
material misstatements or omissions in the registration statement or prospectus
for such offering.

               (vi) Notification. Notify each Holder of Registrable Securities
covered by such registration statement at any time when a prospectus relating
thereto is required to be delivered under the Securities Act of the happening of
any event as a result of which the prospectus included in such registration
statement, as then in effect, includes an untrue statement of a material fact or
omits to state a material fact required to be stated therein or necessary to
make the statements therein not misleading in the light of the circumstances
then existing.

          (f)  Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to Sections 1(b), (c) or
(d) that the selling Holders shall furnish to the Company such information
regarding themselves, the Registrable Securities held by them, and the intended
method of disposition of such securities as shall be required to timely effect
the registration of their Registrable Securities.

          (g)  Indemnification. In the event any Registrable Securities are
included in a registration statement under Sections 1(b), (c) or (d):

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               (i)  By the Company. To the extent permitted by law, the Company
will indemnify and hold harmless each Holder, the partners, officers,
shareholders, employees, representatives and directors of each Holder, any
underwriter (as determined in the Securities Act) for such Holder and each
person, if any, who controls such Holder or underwriter within the meaning of
the Securities Act or the Securities Exchange Act of 1934, as amended, against
any losses, claims, damages, or Liabilities (joint or several) to which they may
become subject under the Securities Act, the Exchange Act or other federal or
state law, insofar as such losses, claims, damages, or liabilities (or actions
in respect thereof) arise out of or are based upon any of the following
statements, omissions or violations (collectively a "Violation"):

                    (A)  any untrue statement or alleged untrue statement of a
material fact contained in such registration statement, including any
preliminary prospectus or final prospectus contained therein or any amendments
or supplements thereto;

                    (B)  the omission or alleged omission to state therein a
material fact required to be stated therein, or necessary to make the statements
therein not misleading, or

                    (C)  any violation or alleged violation by the Company of
the Securities Act, the Exchange Act, any federal or state securities law or any
rule or regulation promulgated under the Securities Act, the Exchange Act or any
federal or state securities law in connection with the offering covered by such
registration statement;

and the Company will reimburse each such Holder, partner, officer, shareholder,
employee, representative, director, underwriter or controlling person for any
legal or other expenses reasonably incurred by them, as incurred, in connection
with investigating or defending any such loss, claim, damage, liability or
action; provided, however, that the indemnity agreement contained in this
subsection shall not apply to amounts paid in settlement of any such loss,
claim, damage, liability or action if such settlement is effected without the
consent of the Company (which consent shall not be unreasonably withheld), nor
shall the Company be liable in any such case for any such loss, claim, damage,
liability or action to the extent that it arises out of or is based upon a
Violation that occurs in reliance upon and in conformity with written
information furnished expressly for use in connection with such registration by
such Holder, partner, officer, shareholder, employee, representative, director,
underwriter or controlling person of such Holder.

               (ii) By Selling Holders. To the extent permitted by law, each
selling Holder will indemnify and hold harmless the Company, each of its
directors, each of its officers who have signed the registration statement, each
person, if any, who controls the Company within the meaning of the Securities
Act, any underwriter and any other Holder selling securities under such
registration statement or any of such other Holder's partners, officers,
shareholders, employees, representatives and directors and any person who
controls such Holder within the meaning of the Securities Act or the Exchange
Act, against any losses, claims, damages or liabilities (joint or several) to
which the Company or any such officer or director, controlling person,
underwriter or other such Holder, partner, officer, shareholder, employee,
representative, director or controlling person of such other Holder may become
subject under the Securities Act, the Exchange Act or other federal or state
law, insofar as such losses, claims, damages or liabilities (or actions in
respect thereto) arise out of or are based upon any Violation, in each case

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to the extent (and only to the extent) that such Violation occurs in reliance
upon and in conformity with written information furnished by such Holder
expressly for use in connection with such registration; and each such Holder
will reimburse any legal or other expenses reasonably incurred by the Company or
any such officer or director, controlling person, underwriter or other Holder,
partner, officer, shareholder, employee, representative, director or controlling
person of such other Holder in connection with investigating or defending any
such loss, claim, damage, liability or action: provided, however, that the
indemnity agreement contained in this subsection shall not apply to amounts paid
in settlement of any such loss, claim, damage, liability or action if such
settlement is effected without the consent of the Holder, which consent shall
not be unreasonably withheld; and provided, further, that the total amounts
payable in indemnity by a Holder under this subsection or otherwise in respect
of any and all Violations shall not exceed in the aggregate the net proceeds
received by such Holder in the registered offering out of which such Violations
arise.

               (iii) Notice. Promptly after receipt by an indemnified party of
notice of the commencement of any action (including any governmental action),
such indemnified party will, if a claim in respect thereof is to be made against
any indemnifying party under this section, deliver to the indemnifying party a
written notice of the commencement thereof and the indemnifying party shall have
the right to participate in, and, to the extent the indemnifying party so
desires, jointly with any other indemnifying party similarly noticed, to assume
the defense thereof with counsel mutually satisfactory to the parties; provided,
however, that an indemnified party shall have the right to retain its own
counsel, with the fees and expenses to be paid by the indemnifying party, to the
extent that representation of such indemnified party by the counsel retained by
the indemnifying party would be inappropriate due to actual or potential
conflict of interests between such indemnified party and any other party
represented by such counsel in such proceeding. The failure to deliver written
notice to the indemnifying party within a reasonable time of the commencement of
any such action shall not relieve such indemnifying party of liability under
this Section 1(g) except to the extent the indemnifying party is prejudiced as a
result thereof.

               (iv) Defect Eliminated in Final Prospectus. The foregoing
indemnity agreements of the Company and Holders are subject to the condition
that, insofar as they relate to any Violation made in a preliminary prospectus
but eliminated or remedied in the amended prospectus on file with the SEC at the
time the registration statement in question becomes effective or the amended
prospectus filed with the SEC pursuant to SEC Rule 424(b) (the "Final
Prospectus"), such indemnity agreement shall not inure to the benefit of any
person if a copy of the Final Prospectus was timely furnished to the indemnified
party and was not furnished to the person asserting the loss, liability, claim
or damage at or prior to the time such action is required by the Securities Act.

               (v)  Contribution. In order to provide for just and equitable
contribution to joint liability under the Securities Act in any case in which
either (A) any Holder exercising rights under this Agreement, or any controlling
person of any such Holder, makes a claim for indemnification pursuant to this
section, but it is judicially determined (by the entry of a final judgment or
decree by a court of competent jurisdiction and the expiration of time to appeal
or the denial of the last right of appeal) that such indemnification may not be
enforced in such case notwithstanding the fact that this section provides for
indemnification in such case, or

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(B) contribution under the Securities Act may be required on the part of any
such selling Holder or any such controlling person in circumstances for which
indemnification is provided under this section; then, and in each such case, the
Company and such Holder will contribute to the aggregate losses, claims, damages
or liabilities to which they may be subject (after contribution from others) in
such proportion so that such Holder is responsible for the portion represented
by the percentage that the public offering price of its Registrable Securities
offered by and sold under the registration statement bears to the public
offering price of all securities offered by and sold under such registration
statement, and the Company and other selling Holders are responsible for the
remaining portion; provided, however, that, in any such case: (X) no such Holder
will be required to contribute any amount in excess of the public offering price
of all such Registrable Securities offered and sold by such Holder pursuant to
such registration statement; and (Y) no person or entity guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
will be entitled to contribution from any person or entity who was not guilty of
such fraudulent misrepresentation.

               (vi) Survival. The obligations of the Company and Holders under
this Section 1(g) shall survive until the third anniversary of the completion of
any offering of Registrable Securities in a registration statement, regardless
of the expiration of any statutes of limitation or extensions of such statutes.

          (h)  Termination of the Company's Obligations. The Company shall have
no obligations pursuant to this Section 1 with respect to any Registrable
Securities proposed to be sold by a Holder in a registration pursuant to Section
1(b), (c) or (d) more than five (5) years after the date of this Agreement or
if, in the opinion of counsel to the Company, all such Registrable Securities to
be sold by any Holder may then be sold under Rule 144 in a single transaction
without exceeding the volume limits thereunder.

          (i)  No Superior Registration Rights to Third Parties. Without the
prior written consent of Siemens AG, the Company covenants and agrees that it
shall not grant, or cause or permit to be created, for the benefit of any person
or entity any registration rights of any kind (whether similar to the demand,
"piggyback" or Form S-3 registration rights described in this Section 1, or
otherwise) relating to shares of the Company's Common Stock or any other
securities of the Company that are superior to the rights granted under this
Section 1. The Company reserves the right to grant registration rights relating
to the Company's Common Stock or any other securities of the Company that are
pari passu with the rights granted to Stockholders under this Section 1.

          (j)  Suspension Provisions. Notwithstanding the foregoing subsections
of this Section 1, the Company shall not be required to take any action with
respect to the registration or the declaration of effectiveness of the
registration statement following written notice to the Holders from the Company
(a "Suspension Notice") of the existence of any state of facts or the happening
of any event (including pending negotiations relating to, or the consummation
of, a transaction, or the occurrence of any event that the Company believes, in
good faith, requires additional disclosure of material, non-public information
by the Company in the registration statement that the Company believes it has a
bona fide business purpose for preserving confidentiality or that renders the
Company unable to comply with the published rules and regulations of the SEC
promulgated under the Securities Act or the Securities Exchange Act, as

                                      -10-
<PAGE>   11

in effect at any relevant time (the "Rules and Regulations") that would result
in (i) the registration statement, any amendment or post-effective amendment
thereto, or any document incorporated therein by reference containing an untrue
statement of a material fact or omitting to state a material fact required to be
stated therein or necessary to make the statements therein not misleading, or
(ii) the prospectus issued under the registration statement, any prospectus
supplement, or any document incorporated therein by reference including an
untrue statement of material fact or omitting to state a material fact necessary
in order to make the statements therein, in the light of the circumstances under
which they were made, not misleading, provided that the Company (X) shall not
issue a Suspension Notice more than once in any 12 month period, (Y) shall use
its best efforts to remedy, as promptly as practicable, but in any event within
90 days of the date on which the Suspension Notice was delivered, the
circumstances that gave rise to the Suspension Notice and deliver to the Holders
notification that the Suspension Notice is no longer in effect and (Z) shall not
issue a Suspension Notice for any period during which the Company's executive
officers are not similarly restrained from disposing of shares of the Company's
Common Stock. Upon receipt of a Suspension Notice from the Company, all time
limits applicable to the Holders under this Section 1 shall automatically be
extended by an amount of time equal to the amount of time the Suspension Notice
is in effect, the Holders will forthwith discontinue disposition of all such
shares pursuant to the registration statement until receipt from the Company of
copies of prospectus supplements or amendments prepared by or on behalf of the
Company (which the Company shall prepare promptly), together with a notification
that the Suspension Notice is no longer in effect, and if so directed by the
Company, the Holders will deliver to the Company all copies in their possession
of the prospectus covering such shares current at the time of receipt of any
Suspension Notice.

     2.   RIGHTS IN THE EVENT OF A CORPORATE EVENT

          (a)  Corporate Event. A "Corporate Event" shall mean any of the
following, whether accomplished through one or a series of related transactions:
(i) any transaction, other than an issuance of securities in connection with the
acquisition of an unaffiliated third party in an arms length transaction, that
results in a greater than thirty percent (30%) change in the total outstanding
number of voting securities (which, for purposes of this Agreement, shall mean
all securities of the Company that presently are, or would be upon conversion,
exchange or exercise, entitled to vote in the election of directors) of the
Company immediately prior to such issuance (other than any such change solely as
a result of a stock split, stock dividend or other securities of the Company on
a pro rata basis); (ii) an acquisition of the Company or any of its "Significant
Subsidiaries" (as defined in the SEC's Rule 1-02(w) of Regulation S-X) by
consolidation, merger (regardless of whether the Company is the survivor of such
merger or not), share purchase or exchange or other reorganization or
transaction in which the holders of the Company's or such Significant
Subsidiary's outstanding voting securities immediately prior to such transaction
own, immediately after such transaction, securities representing less than fifty
percent (50%) of the voting power of the Company, any such Significant
Subsidiary or the person issuing such securities or surviving such transaction,
as the case may be, provided that this clause (ii) shall not apply to the pro
rata distribution by the Company to its shareholders of all the voting
securities of any of its subsidiaries; (iii) the acquisition of all or
substantially all the assets of the Company or any Significant Subsidiary; (iv)
the grant by the Company or any of its Significant Subsidiaries of an exclusive
license for any material portion of the Company's or such Significant
Subsidiary's intellectual property to a person other than Siemens AG or any of
its

                                      -11-
<PAGE>   12

subsidiaries; and (v) any transaction or series of related transactions that
results in the failure of the majority of the members of the Company's Board of
Directors immediately prior to the closing of such transaction or series of
related transactions failing to constitute a majority of the Company's Board of
Directors (or its successor) immediately following such transaction or series of
related transactions.

          (b)  Notice of Corporate Events. Until the expiration of the second
anniversary of the Closing, as defined in the Asset Purchase Agreement, (such
period from the date hereof through such second anniversary being referred to
herein as the "Initial Rights Period"), the Company shall provide all Holders
with written notice of the existence of any offer (written or oral) from any
person for a proposed Corporate Event. Any notice shall be delivered to the all
Holders within two (2) business days after the date the Company first becomes
aware of such offer or proposed Corporate Event.

     3.   ASSIGNMENT

     The rights of the Stockholders under Section 1 are transferable to any
purchaser or transferee of the Acquired Shares; provided, however, that any such
assignee shall receive such assigned rights subject to all the terms and
conditions of this Agreement.

     4.   EXCHANGE ACT REPORTS

     The Company agrees to:

          (a)  Use commercially reasonable efforts to file with the SEC in a
timely manner all reports and other documents required of the Company under the
Securities Act and the Securities Exchange Act of 1934 (the "Exchange Act").

          (b)  Furnish to each Holder forthwith upon request a written statement
by the Company that it has complied with the reporting requirements of the
Securities Act and the Exchange Act, or that it qualifies as a registrant whose
securities may be resold pursuant to Form S-3.

          (c)  Make and keep public information available as those terms are
understood and defined in Rule 144 under the Securities Act.

          (d)  So long as Stockholders own the Acquired Shares, furnish to the
Stockholders upon request a written statement by the Company as to their
compliance with the reporting requirements of Rule 144, and of the Securities
Act and the Exchange Act and such other reports and documents so filed with the
SEC as Stockholders may reasonably request in availing itself of any rule or
regulation of the SEC allowing Stockholders to sell any such securities without
registration.

     5.   INFORMATION RIGHTS

          (a)  Financial Information. The Company covenants and agrees that,
commencing on the date of this Agreement and continuing for so long as the
Holders hold at least 40,000 Acquired Shares or shares of Common Stock issued,
the Company shall:

                                      -12-
<PAGE>   13

               (i)  Annual Reports. Furnish to the Holders promptly following
the filing of such report with the SEC a copy of the Company's Annual Report on
Form 10-K for each fiscal year, which shall include a consolidated balance sheet
as of the end of such fiscal year, a consolidated statement of income and a
consolidated statement of cash flows of the Company and its subsidiaries for
such year, setting forth in each case in comparative form the figures from the
Company's previous fiscal year, all prepared in accordance with generally
accepted accounting principles and practices and audited by nationally
recognized independent certified public accountants. In the event the Company
shall no longer be required to file Annual Reports on Form 10-K, the Company
shall, within ninety (90) days following the end of each respective fiscal year,
deliver to the Holders a copy of such balance sheets, statements of income and
statements of cash flows.

               (ii) Quarterly Reports. Furnish to the Holders promptly following
the filing of such report with the SEC, a copy of each of the Company's
Quarterly Reports on Form 10-Q, which shall include a consolidated balance sheet
as of the end of the respective fiscal quarter, consolidated statements of
income and consolidated statements of cash flows of the Company and its
subsidiaries for the respective fiscal quarter and for the year to-date, setting
forth in each case in comparative form the figures from the comparable periods
in the Company's immediately preceding fiscal year, all prepared in accordance
with generally accepted accounting principles and practices (except, in the case
of any Form 10-Q, as may otherwise be permitted by Form 10-Q), but all of which
may be unaudited. In the event the Company shall no longer be required to file
Quarterly Reports on Form l0-Q, the Company shall, within forty-five (45) days
following the end of each of the first three (3) fiscal quarters of each fiscal
year, deliver to the Holders a copy of such balance sheets, statements of income
and statements of cash flows.

          (b)  SEC Filings. The Company shall deliver to the Holders copies of
each other document filed with the SEC on a non-confidential basis promptly
following the filing of such document with the SEC.

     6.   MISCELLANEOUS

          (a)  Successors and Assigns. The terms and conditions of this
Agreement will inure to the benefit of and be binding upon the respective
successors and permitted assigns of the parties.

          (b)  Governing Law. This Agreement will be governed by and construed
under the internal laws of the State of Delaware, without reference to
principles of conflict of laws or choice of laws.

          (c)  Counterparts. This Agreement may be executed in two or more
counterparts, each of which will be deemed an original, but all of which
together will constitute one and the same instrument.

          (d)  Headings. The headings and captions used in this Agreement are
used for convenience only and are not to be considered in construing or
interpreting this Agreement. All references in this Agreement to sections,
paragraphs, exhibits and schedules will, unless

                                      -13-
<PAGE>   14

otherwise provided, refer to sections and paragraphs hereof and exhibits and
schedules attached hereto, all of which exhibits and schedules are incorporated
herein by this reference.

          (e)  Notices. Any notice required or permitted under this Agreement
shall be given in writing, shall be effective when received, and shall in any
event be deemed received and effectively given upon personal delivery to the
party to be notified or three (3) business days after deposit with the United
States Post Office, by registered or certified mail, postage prepaid, or one (1)
business day after deposit with a nationally recognized courier service such as
Federal Express for next business day delivery under circumstances in which such
service guarantees next business day delivery, or one (1) business day after
facsimile with copy delivered by registered or certified mail, in any case,
postage prepaid and addressed to the party to be notified at the address
indicated for such party on the signature page hereof or at such other address
as the Stockholders or the Company may designate by giving at least ten (10)
days advance written notice pursuant to this Section 4(e).

          (f)  Amendments and Waivers. This Agreement may be amended and the
observance of any term of this Agreement may be waived (either generally or in a
particular instance and either retroactively or prospectively), only with the
written consent of the Company and the holders of Acquired Shares representing
at least a majority of the total aggregate number of Acquired Shares then
outstanding (excluding any of such shares that have been sold in a transaction
in which rights under Section 1 are not assigned in accordance with this
Agreement or sold to the public pursuant to SEC Rule 144 or otherwise). Any
amendment or waiver effected in accordance with this Section 4(f) will be
binding upon the Stockholders, the Company and their respective successors and
assigns. Notwithstanding the foregoing, the provisions of Sections 1 and 2 may
not be amended without the written consent of the Company and the Stockholders,
which may be withheld in either of their sole and absolute discretions.

          (g)  Severability. If any provision of this Agreement is held to be
unenforceable under applicable law, such provision will be excluded from this
Agreement and the balance of the Agreement will be interpreted as if such
provision was so excluded and will be enforceable in accordance with its terms.

          (h)  Entire Agreement. This Agreement, together with the Asset
Purchase Agreement and all exhibits and schedules hereto and thereto constitutes
the entire agreement and understanding of the parties with respect to the
subject matter hereof and supersedes any and all prior negotiations,
correspondence, agreements, understandings, duties or obligations between the
parties with respect to the subject matter hereof.

          (i)  Further Assurances. From and after the date of this Agreement
upon the request of the Company or the Stockholders, the Company and the
Stockholders will execute and deliver such instruments, documents or other
writings, and take such other actions, as may be reasonably necessary or
desirable to confirm and carry out and to effectuate fully the intent and
purposes of this Agreement.

          (j)  Meaning of Include and Including. Whenever in this Agreement the
word "include" or "including" is used, it shall be deemed to mean "include,
without limitation" or

                                      -14-
<PAGE>   15

"including, without limitation," as the case may be, and the language following
"include" or "including" shall not be deemed to set forth an exhaustive list.

          (k)  Fees, Costs and Expenses. All fees, costs and expenses (including
attorneys' fees and expenses) incurred by either party hereto in connection with
the preparation, negotiation and execution of this Agreement and the Purchase
Agreement and the consummation of the transactions contemplated hereby and
thereby (including the costs associated with any filings with, or compliance
with any of the requirements of, any governmental authorities), shall be the
sole and exclusive responsibility of such party.

          (l)  Stock Splits, Dividends and other Similar Events. The provisions
of this Agreement (including the number of shares of Common Stock and other
securities described herein) shall be appropriately adjusted to reflect any
stock split, stock dividend, reorganization or other similar event that may
occur with respect to the Company after the date hereof.

             [THE BALANCE OF THIS PAGE IS INTENTIONALLY LEFT BLANK.]

                                      -15-
<PAGE>   16

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

                                        PROXIM, INC.

                                        By: /s/ Keith E. Glover
                                            ------------------------------------

                                        Name: Keith E. Glover
                                              ----------------------------------

                                        Title: VP & CFO
                                               ---------------------------------

                                        Address:

                                        510 DeGuigne Drive
                                        Sunnyvale, California 94086
                                        Telephone No: (408) 731-2700
                                        Facsimile No: (408) 731-3670
                                        Attention: Chief Financial Officer

                                        with copies to:

                                        Wilson Sonsini Goodrich & Rosati
                                        650 Page Mill Road
                                        Palo Alto, CA 94304
                                        Telephone No: (650) 493-9300
                                        Facsimile No: (650) 493-6811
                                        Attention: Jeffrey D. Saper
                                                       Robert G. Day

<PAGE>   17

                                        SIEMENS AKTIENGESELLSCHAFT

                                        By: /s/ C. Caselitz
                                            ------------------------------------

                                        Name: C. Caselitz
                                              ----------------------------------

                                        Title: General Manager DP
                                               ---------------------------------

                                        By: /s/ Gerwin Zott
                                            ------------------------------------

                                        Name: Gerwin Zott
                                              ----------------------------------

                                        Title: Head of Legal Services ICM
                                               ---------------------------------
                                        Address:

                                        Siemens Aktiengesellschaft
                                        Attention: Mr. Klaus Karl,
                                                   VP Business Development
                                        81675 Munich
                                        Grillparzerstr. 10-18
                                        Germany

                                        With a copy to:

                                        Siemens Aktiengesellschaft
                                        Rechtsabteiilung ZFR 2
                                        Hofmmannstr. 51
                                        81379
                                        Attention: Mr. Gerwin Zott

<PAGE>   18

                                        SIEMENS INFORMATION AND
                                        COMMUNICATION MOBILE LLC

                                        By: /s/ Axel Meier
                                            ------------------------------------

                                        Name: Axel Meier
                                              ----------------------------------

                                        Title: Acting Chief Financial Officer
                                               ---------------------------------

                                        Address:

                                        Siemens Information and Communication
                                          Mobile LLC
                                        2200 Grand Avenue Parkway
                                        Austin, TX 78728
                                        Attention: President

                                        With a copy to:

                                        Siemens Information and Communication
                                          Mobile LLC
                                        2200 Grand Avenue Parkway
                                        Austin, TX 78728
                                        Attention: Legal Department<PAGE>   1
                                                                    EXHIBIT 4.18

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAWS OF ANY STATE.
THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN
FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED
TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE
SECURITIES LAWS.

                                     AVIRON

               WARRANT FOR THE PURCHASE OF SHARES OF COMMON STOCK

No. CSW- 4                                                          9,398 Shares

         FOR VALUE RECEIVED, AVIRON, a Delaware corporation (the "Company"),
with its principal office at 297 North Bernardo Avenue, Mountain View, CA 94043,
hereby certifies that The Procter & Gamble Company, or its assigns (the
"Holder"), is entitled, subject to the provisions of this Warrant, to purchase
from the Company, at any time after the Eligibility Date (as defined below) and
prior to the Expiration Date (as defined below), nine thousand three hundred
ninety-eight (9,398) fully paid and nonassessable shares of Common Stock of the
Company, at an exercise price per share equal to fifty-three dollars ($53.00)
(the "Exercise Price"). The term "Common Stock" shall mean the aforementioned
Common Stock of the Company, together with any other equity securities that may
be issued by the Company in addition thereto or in substitution therefor as
provided herein.

         The number of shares of Common Stock to be received upon the exercise
of this Warrant and the price to be paid for a share of Common Stock are subject
to adjustment from time to time as hereinafter set forth. The shares of Common
Stock deliverable upon such exercise, as adjusted from time to time, are
hereinafter sometimes referred to as "Warrant Shares."

SECTION 1. EXERCISE OF WARRANT. Subject to Section 11 below, this Warrant shall
be immediately exercisable in whole, but not in part, upon the earlier of: (i)
the date of receipt by the Company of written acceptance by the United States
Food and Drug Administration of the Company's filing of its Biologics License
Application for its product, FluMist(TM), or (ii) ten (10) days prior to the
Expiration Date (the "Eligibility Date"). This Warrant may be exercised in
whole, but not in part, by presentation and surrender to the Company at its
principal office at the address set forth in the initial paragraph hereof (or at
such other address as the Company may hereafter notify the Holder in writing)
with the Purchase Form annexed hereto duly executed and accompanied by proper
payment of the Exercise Price in lawful money of the United States of America in
the form of a check, subject to collection, for the number of Warrant Shares
specified

<PAGE>   2

in the Purchase Form. Partial exercise of this Warrant shall not be permitted.
Upon receipt by the Company of this Warrant and such Purchase Form, together
with proper payment of the Exercise Price, at such office, the Holder shall be
deemed to be the holder of record of the Warrant Shares, notwithstanding that
the stock transfer books of the Company shall then be closed or that
certificates representing such Warrant Shares shall not then be actually
delivered to the Holder.

         SECTION 2. NET ISSUE EXERCISE. Notwithstanding any provisions herein to
the contrary, in lieu of exercising this Warrant for cash, the Holder may elect
to receive shares equal to the value (as determined below) of this Warrant (or
the portion thereof being canceled) by surrender of this Warrant at the
principal office of the Company together with notice of such election in which
event the Company shall issue to the Holder a number of shares of Common Stock
computed using the following formula:

                                  X = Y (A - B)
                                      ---------
                                          A

                Where X = the number of shares of Common Stock to be issued to
                the Holder

                Y = the number of shares of Common Stock purchasable under the
                Warrant (at the date of such calculation)

                A = the fair market value as determined by the closing sales
                price on the date of exercise of one share of the Company's
                Common Stock as quoted on NASDAQ

                B = Exercise Price (as adjusted to the date of such calculation)

         SECTION 3. RESERVATION OF SHARES. The Company hereby agrees that at all
times there shall be reserved for issuance and delivery upon exercise of this
Warrant all shares of its Common Stock or other shares of capital stock of the
Company from time to time issuable upon exercise of this Warrant. All such
shares shall be duly authorized and, when issued upon such exercise in
accordance with the terms of this Warrant, shall be validly issued, fully paid
and nonassessable.

         SECTION 4. FRACTIONAL INTEREST. The Company will not issue a fractional
share of Common Stock upon exercise of this Warrant. Instead, the Company will
deliver its check for the current fair market value of the fractional share, as
determined in good faith by the Board of Directors of the Company.

         SECTION 5. ASSIGNMENT OR LOSS OF WARRANT.

                (a) Except as provided in Section 9, the Holder of this Warrant
shall be entitled, without obtaining the consent of the Company, to assign its
interest in this Warrant in whole to any person or persons. Subject to the
provisions of Section 9, upon surrender of this Warrant to the Company or at the
office of its stock transfer agent or warrant agent, with the Assignment Form
annexed hereto duly executed and funds sufficient to pay any transfer tax, the

                                       2.
<PAGE>   3

Company shall, without charge, execute and deliver a new Warrant or Warrants in
the name of the assignee or assignees named in such instrument of assignment,
and this Warrant shall promptly be canceled.

                (b) Upon receipt of evidence satisfactory to the Company of the
loss, theft, destruction or mutilation of this Warrant, and (in the case of
loss, theft or destruction) of indemnification satisfactory to the Company, and
upon surrender and cancellation of this Warrant, if mutilated, the Company shall
execute and deliver a new Warrant of like tenor and date.

         SECTION 6. RIGHTS OF THE HOLDER. The Holder shall not, by virtue
hereof, be entitled to any rights of a shareholder in the Company, either at law
or equity, and the rights of the Holder are limited to those expressed in this
Warrant. Nothing contained in this Warrant shall be construed as conferring upon
the Holder hereof the right to vote or to consent or to receive notice as a
shareholder of the Company on any matters or with respect to any rights
whatsoever as a shareholder of the Company. No dividends or interest shall be
payable or accrued in respect of this Warrant or the interest represented hereby
or the Warrant Shares purchasable hereunder until, and only to the extent that,
this Warrant shall have been exercised in accordance with its terms.

         SECTION 7. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES. The
number and kind of securities purchasable upon the exercise of the Warrant and
the Exercise Price shall be subject to adjustment from time to time upon the
occurrence of certain events, as follows:

                (a) RECLASSIFICATION OF OUTSTANDING SECURITIES. In case of any
reclassification, change or conversion of securities of the class issuable upon
exercise of this Warrant (other than a change in par value, or from par value to
no par value, or from no par value to par value, or as a result of a subdivision
or combination), the Company shall execute a new Warrant (in form and substance
reasonably satisfactory to the Holder of this Warrant) providing that the Holder
of this Warrant shall have the right to exercise such new Warrant and upon such
exercise to receive, in lieu of each share of Common Stock theretofore issuable
upon exercise of this Warrant, the kind and amount of shares of stock, other
securities, money and property receivable upon such reclassification or change
by a holder of one share of Common Stock. Such new Warrant shall provide for
adjustments that shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Section 7. The provisions of this subsection
(a) shall similarly apply to successive reclassification or changes.

                (b) SUBDIVISIONS OR COMBINATION OF SHARES. If the Company at any
time while this Warrant remains outstanding and unexpired shall subdivide or
combine its Common Stock, the Exercise Price and the number of Warrant Shares
issuable upon exercise hereof shall be proportionately adjusted.

                (c) STOCK DIVIDENDS. If the Company at any time while this
Warrant is outstanding and unexpired shall pay a dividend payable in shares of
Common Stock (except any distribution specifically provided for in the foregoing
subsections (a) and (b)), then the Exercise Price shall be adjusted, from and
after the date of determination of shareholders entitled to receive such
dividend or distribution, to that price determined by multiplying the Exercise
Price

                                       3.
<PAGE>   4

in effect immediately prior to such date of determination by a fraction (a) the
numerator of which shall be the total number of shares of Common Stock
outstanding immediately prior to such dividend or distribution, and (b) the
denominator of which shall be the total number of shares of Common Stock
outstanding immediately after such dividend or distribution and the number of
Warrant Shares subject to this Warrant shall be proportionately adjusted.

                (d) NOTICE OF RECORD DATE. In the event of any taking by the
Company of a record of its shareholders for the purpose of determining
shareholders who are entitled to receive payment of any dividend (other than a
cash dividend) or other distribution, any right to subscribe for, purchase or
otherwise acquire any share of any class or any other securities or property, or
to receive any other right, or for the purpose of determining shareholders who
are entitled to vote in connection with any proposed merger or consolidation of
the Company with or into any other corporation, or any proposed sale, lease or
conveyance of all or substantially all of the assets of the Company, or any
proposed liquidation, dissolution or winding up of the Company, the Company
shall mail to the Holder of this Warrant, at least ten days prior to the date
specified therein, a notice specifying the date on which any such record is to
be taken for the purpose of such dividend, distribution or right, and the amount
and character of such dividend, distribution or right.

                (e) NO ADJUSTMENT UPON EXERCISE OF WARRANTS. No adjustments
shall be made under any Section herein in connection with the issuance of
Warrant Shares upon exercise of the Warrants.

         SECTION 8. OFFICER'S CERTIFICATE. Whenever the Exercise Price shall be
adjusted as required by the provisions of Section 7, the Company shall deliver
an officer's certificate showing the adjusted Exercise Price determined as
herein provided, setting forth in reasonable detail the facts requiring such
adjustment and the manner of computing such adjustment. Each such officer's
certificate shall be signed by the chairman, president or chief financial
officer of the Company.

         SECTION 9. TRANSFER TO COMPLY WITH THE SECURITIES ACT OF 1933. This
Warrant may not be exercised and neither this Warrant nor any of the Warrant
Shares, nor any interest in either, may be sold, assigned, pledged,
hypothecated, encumbered or in any other manner transferred or disposed of, in
whole or in part, except in compliance with applicable United States federal and
state securities or Blue Sky laws and the terms and conditions hereof. Each
Warrant shall bear a legend in substantially the same form as the legend set
forth on the first page of this Warrant. Each certificate for Warrant Shares
issued upon exercise of this Warrant, unless at the time of exercise such
Warrant Shares are acquired pursuant to a registration statement that has been
declared effective under the Act, shall bear a legend substantially in the
following form:

         THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES
         LAWS OF ANY STATE. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON
         TRANSFERABILITY AND RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT
         AS PERMITTED UNDER THE ACT AND THE

                                       4.
<PAGE>   5

         APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
         THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF
         COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT
         THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND
         ANY APPLICABLE STATE SECURITIES LAWS.

Any certificate for any Warrant Shares issued at any time in exchange or
substitution for any certificate for any Warrant Shares bearing such legend
(except a new certificate for any Warrant Shares issued after the acquisition of
such Warrant Shares pursuant to a registration statement that has been declared
effective under the Act) shall also bear such legend unless, in the opinion of
counsel for the Company, the Warrant Shares represented thereby need no longer
be subject to the restriction contained herein. The provisions of this Section 9
shall be binding upon all subsequent Holders of certificates for Warrant Shares
bearing the above legend and all subsequent Holders of this Warrant, if any. In
addition in connection with the issuance of this Warrant, the Holder
specifically represents to the Company by acceptance of this Warrant as follows:

                (a) The Holder is aware of the Company's business affairs and
financial condition, and has acquired information about the Company sufficient
to reach an informed and knowledgeable decision to acquire this Warrant. The
Holder is acquiring this Warrant for its own account for investment purposes
only and not with a view to, or for the resale in connection with, any
"distribution" thereof in violation of the Act.

                (b) The Holder understands that this Warrant has not been
registered under the Act in reliance upon a specific exemption therefrom, which
exemption depends upon, among other things, the bona fide nature of the Holder's
investment intent as expressed herein.

                (c) The Holder further understands that this Warrant must be
held indefinitely unless subsequently registered under the Act and qualified
under any applicable state securities laws, or unless exemptions from
registration and qualification are otherwise available.

                (d) The Holder is aware of the provisions of Rule 144
promulgated under the Act, which, in substance, permit limited public resale of
"restricted securities" acquired, directly or indirectly, from the issuer
thereof (or from an affiliate of such issuer), in a non-public offering subject
to the satisfaction of certain conditions, if applicable, including, among other
things, the availability of certain public information about the Company, the
resale occurring not less than one year after the party has purchased and paid
for the securities to be sold; the sale being made through a broker in an
unsolicited "broker's transaction" or in transactions directly with a market
maker (as said term is defined under the Securities Exchange Act of 1934, as
amended (the "Exchange Act")) and the amount of securities being sold during any
three month period not exceeding the specified limitations stated therein.

                (e) The Holder further understands that in the event all of the
requirements of Rule 144 are not satisfied, registration under the Act,
compliance with Regulation A, or some other registration exemption will be
required; and that, notwithstanding the fact that Rule 144 is not exclusive, the
staff of the Securities and Exchange Commission (the "SEC") has expressed

                                       5.
<PAGE>   6

its opinion that persons proposing to sell private placement securities other
than in a registered offering and otherwise than pursuant to Rule 144 will have
a substantial burden of proof in establishing that an exemption from
registration is available for such offers or sales, and that such persons and
their respective brokers who participate in such transactions do so at their own
risk.

         SECTION 10. REGISTRATION RIGHTS. If, after this Warrant has been
exercised in full, the Holder is unable to sell or otherwise dispose of all the
Warrant Shares delivered upon such exercise without restriction pursuant to Rule
144, then with respect to such Warrant Shares, the Holder shall be entitled to
registration rights as provided in this Section 10.

                (a) REGISTRATION REQUIREMENTS.

                    (i) Except as provided in paragraph (iv) below, if the
Company shall receive a written request from the Holder that the Company file a
registration statement under the Act covering the registration of those Warrant
Shares which Holder cannot sell or otherwise dispose pursuant to Rule 144, then
the Company shall use its best efforts to prepare and file a registration
statement on Form S-3 with the SEC under the Act within 30 days of the receipt
of such written request, to register such Warrant Shares by the Holder (the
"Registration Statement") and to use its best efforts to cause the Registration
Statement to be declared effective as soon as practicable. In the event that at
any time the filing of such Registration Statement is undertaken or is required
to be undertaken the Company fails to qualify for use of Form S-3 (or other
available form for similar type securities registration) for purposes of
registering for resale the Warrant Shares, the Company shall cause a
registration statement on Form S-1 (or other available form for similar type
securities registration) to be filed as soon as practicable after its receipt of
the request specified in this Section 10(a)(i). The Holder agrees to furnish
promptly to the Company in writing all information reasonably required by the
Company to file such Registration Statement. The Company shall only be obligated
to effect one (1) registration pursuant to this Section 10.

                    (ii) The Company shall pay all Registration Expenses (as
defined below) in connection with any registration, qualification or compliance
hereunder, and Holder shall pay all Selling Expenses (as defined below).
"Registration Expenses" shall mean all expenses, except for Selling Expenses,
incurred by the Company in complying with the registration provisions herein
described, including, without limitation, all registration, qualification and
filing fees, printing expenses, escrow fees, fees and disbursements of counsel
and independent public accountants for the Company, blue sky fees, transfer
agent fees and expenses and the expense of any special audits incident to or
required by any such registration. "Selling Expenses" shall mean selling
commissions, underwriting fees and stock transfer taxes applicable to the
Warrant Shares.

                    (iii) In the case of the registration effected by the
Company pursuant to these registration provisions, the Company will use its best
efforts to: (1) keep such registration effective until the earliest of (A) the
first anniversary of the effective date of the Registration Statement, (B) such
date as all of the Warrant Shares have been resold or (C) such time as all of
the Warrant Shares held by Holder can be sold without restriction pursuant to
Rule 144 under the Act; (2) prepare and file with the SEC such amendments and
supplements to the Registration

                                       6.
<PAGE>   7

Statement and the prospectus used in connection with the Registration Statement
as may be necessary to comply with the provisions of the Act with respect to the
disposition of all securities covered by the Registration Statement; (3) furnish
such number of prospectuses and other documents incident thereto, including any
amendment of or supplement to the prospectus, as Holder from time to time may
reasonably request in order to facilitate the public sale or other disposition
of all or any of the Warrant Shares held by Holder; (4) cause all Warrant Shares
registered as described herein to be listed on each securities exchange and
quoted on each quotation service on which similar securities issued by the
Company are then listed or quoted; (5) provide a transfer agent and registrar
for all Warrant Shares registered pursuant to the Registration Statement and a
CUSIP number for all such Warrant Shares; (6) otherwise use its best efforts
promptly to comply with all applicable rules and regulations of the SEC; and (7)
file the documents required of the Company and otherwise use its best efforts
promptly to obtain, if applicable, and maintain requisite blue sky clearance in
(A) all jurisdictions in which any of the Warrant Shares are originally sold and
(B) all other states specified in writing by Holder, provided as to clause (B),
however, that the Company shall not be required to qualify to do business or
consent to service of process in any state in which it is not now so qualified
or has not so consented. The Company shall use its best efforts to qualify for
use of Form S-3 or other similar form then available under the Act to register
the resale of the Warrant Shares and to maintain such qualification during the
periods described in paragraph (i).

                    (iv) The Company may delay the filing of the Registration
Statement for up to forty-five (45) days by giving written notice to Holder if
the Board of Directors of the Company shall have determined in good faith that
the Company may be required to disclose any material corporate development which
disclosure may have a material effect on the Company.

                    (v) Following the effectiveness of the Registration
Statement, the Company may, at any time, but not more than once in any six-month
period, suspend the effectiveness of such Registration Statement for up to 30
days, as appropriate (a "Suspension Period"), by giving notice to Holder, if the
Company shall have determined that the Company may be required to disclose any
material corporate development which disclosure may have a material effect on
the Company. The Company agrees to use commercially reasonable efforts to
minimize the length of any such suspension. The duration of any Suspension
Period shall be added to the period of time that the Company agrees to keep the
Registration Statement effective. Holder agrees that, upon receipt of any notice
from the Company of a Suspension Period, Holder shall forthwith discontinue
disposition of Warrant Shares covered by such Registration Statement or
prospectus until Holder (i) is advised in writing by the Company that the use of
the applicable prospectus may be resumed, (ii) has received copies of a
supplemental or amended prospectus, if applicable, and (iii) has received copies
of any additional or supplemental filings which are incorporated or deemed to be
incorporated by reference in such prospectus.

                    (vi) The Company will, as expeditiously as possible, notify
Holder (1) of the effective date of the Registration Statement and the date when
any post-effective amendment to the Registration Statement becomes effective;
(2) of any stop order or notification from the SEC or any other jurisdiction as
to the suspension of the effectiveness of the Registration Statement; and (3) of
the end of any suspension hereunder.

                                       7.
<PAGE>   8

                    (vii) With a view to making available to Holder the benefits
of Rule 144 and any other rule or regulation of the SEC that may at any time
permit Holder to sell the Warrant Shares to the public without registration or
pursuant to registration, the Company covenants and agrees to: (1) make and keep
public information available, as those terms are understood and defined in Rule
144, until the earlier of (A) the second anniversary of the date hereof or (B)
such date as all of the Warrant Shares shall have been resold; (2) file with the
SEC in a timely manner all reports and other documents required of the Company
under the Exchange Act and maintain registration of its Common Stock under
Section 12 of the Exchange Act until the earlier of (A) the second anniversary
of the date hereof or (B) such date as all of the Warrant Shares shall have been
resold; and (3) furnish to Holder upon request, as long as Holder owns any
Warrant Shares, (A) a written statement by the Company that it has complied with
the reporting requirements of the Exchange Act, (B) a copy of the most recent
annual or quarterly report of the Company, and (C) such other information as may
be reasonably requested in order to avail Holder of any rule or regulation of
the SEC that permits the selling of any such Warrant Shares without
registration.

                (b) INDEMNIFICATION AND CONTRIBUTION.

                    (i) The Company agrees to indemnify Holder and hold Holder
harmless from and against any losses, claims, damages or liabilities (or actions
or proceedings in respect thereof) to which Holder may become subject (under the
Act, Exchange Act, state securities laws or otherwise) insofar as such losses,
claims, damages or liabilities (or actions proceedings or settlements in respect
thereof) arise out of, or are based upon, (1) any untrue statement (or alleged
untrue statement) of a material fact contained in the Registration Statement, on
the effective date thereof or any preliminary prospectus or final prospectus
contained therein, or any amendment or supplement thereto, (2) the omission or
the alleged omission of a material fact required to be stated therein or
necessary to make the statements therein not misleading or (3) any failure by
the Company (or its agents) to fulfill any undertaking included in the
Registration Statement, and the Company will, as incurred, reimburse Holder for
any legal or other expenses reasonably incurred in investigating, defending or
preparing to defend any such action, loss, damage, proceeding or claim;
provided, however, that the Company shall not be liable in any such case to the
extent that such loss, claim, damage or liability arises out of, or is based
upon (1) an untrue statement (or omission) made in such Registration Statement
in reliance upon and in conformity with written information furnished to the
Company by or on behalf of Holder specifically for use in preparation of the
Registration Statement, or (2) any untrue statement (or omission) in any
Prospectus that is corrected in any subsequent Prospectus that was delivered to
Holder by the Company prior to the pertinent sale or sales by Holder. The
Company will reimburse Holder for any legal or other expenses reasonably
incurred in investigating, defending or preparing to defend any such action,
proceeding or claim notwithstanding the absence of a judicial determination as
to the propriety and enforceability of the obligations under this section and
the possibility that such payments might later be held to be improper, provided,
that (1) to the extent any such payment is ultimately held to be improper, the
persons receiving such payments shall promptly refund them and (2) such persons
shall provide to the Company, upon request, reasonable assurances of their
ability to effect any refund, when and if due.

                    (ii) Holder agrees to indemnify and hold harmless the
Company from and against any losses, claims, damages or liabilities (or actions
or proceedings in respect

                                       8.
<PAGE>   9

thereof) to which the Company may become subject (under the Act or otherwise)
insofar as such losses, claims, damages or liabilities (or actions or
proceedings in respect thereof) arise out of, or are based upon (1) an untrue
statement made in such Registration Statement in reliance upon and in conformity
with written information furnished to the Company by or on behalf of Holder
specifically for use in preparation of the Registration Statement, provided,
however, that Holder shall not be liable in any such case for any untrue
statement included in any Prospectus which statement has been corrected, in
writing, by Holder and delivered to the Company before the sale from which such
loss occurred and the Company has had the opportunity to amend or supplement the
prospectus prior to such sale, or (2) any untrue statement in any Prospectus
that is corrected in any subsequent Prospectus that was delivered to the Holder
prior to the pertinent sale or sales by Holder, provided, further, however, that
the liability of Holder hereunder shall be limited to the proceeds received by
Holder from the sale of the Warrant Shares covered by such Registration
Statement; and provided, further, however, that the obligations of Holder
hereunder shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability, or action if such settlement is effected without the consent
of Holder. Holder will reimburse the Company for any legal or other expenses
reasonably incurred in investigating, defending or preparing to defend any such
action, proceeding or claim up to the limits set forth herein notwithstanding
the absence of a judicial determination as to the propriety and enforceability
of the obligations under this section and the possibility that such payments
might later be held to be improper, provided, that (i) to the extent any such
payment is ultimately held to be improper, the persons receiving such payments
shall promptly refund them and (ii) such persons shall provide to Holder, upon
request, reasonable assurances of their ability to effect any refund, when and
if due.

                    (iii) Promptly after receipt by any indemnified person of a
notice of a claim or the commencement of any action in respect of which
indemnity is to be sought against an indemnifying person pursuant to this
Section 10(b), such indemnified person shall notify the indemnifying person in
writing of such claim or of the commencement of such action, and, subject to the
provisions hereinafter stated, in case any such action shall be brought against
an indemnified person and the indemnifying person shall have been notified
thereof, the indemnifying person shall be entitled to participate therein, and,
to the extent that it shall wish, to assume and undertake the defense thereof,
with counsel reasonably satisfactory to the indemnified person. After notice
from the indemnifying person to such indemnified person of the indemnifying
person's election to assume and undertake the defense thereof, the indemnifying
person shall not be liable to such indemnified person for any legal expenses
subsequently incurred by such indemnified person in connection with the defense
thereof; provided, however, that if there exists or shall exist a conflict of
interest that would make it inappropriate in the reasonable judgment of the
indemnified person for the same counsel to represent both the indemnified person
and such indemnifying person or any affiliate or associate thereof, the
indemnified person shall be entitled to retain its own counsel at the expense of
such indemnifying person.

                    (iv) If the indemnification provided for in this Section
10(b) is unavailable to or insufficient to hold harmless an indemnified party
under paragraph (i) or (ii) above in respect of any losses, claims, damages or
liabilities (or actions proceedings or settlements in respect thereof) referred
to therein, then the indemnifying party shall contribute to the amount paid or
payable by such indemnified party as result of such losses, claims, damages or
liabilities (or actions in respect thereof) in such proportion as is appropriate
to reflect the

                                       9.
<PAGE>   10

relative fault of the Company on the one hand and the Holder on the other in
connection with the statements or omissions which resulted in such losses,
claims, damages or liabilities (or actions in respect thereof), as well as any
other relevant equitable considerations. The relative fault shall be determined
by reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission or alleged omission to state a
material fact relates to information supplied by the Company on the one hand or
Holder on the other and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission.
The Company and Holder agree that it would not be just and equitable if
contribution pursuant to this paragraph (iv) were determined by pro rata
allocation or by any other method of allocation which does not take account of
the equitable considerations referred to above in this paragraph (iv). The
amount paid or payable by an indemnified party as a result of the losses,
claims, damages, or liabilities (or actions in respect thereof) referred to
above in this paragraph (iv) shall be deemed to include any legal or other
expenses reasonably incurred by such indemnified party in connection with
investigating or defending any such action or claim. Notwithstanding the
provisions of this paragraph (d), Holder shall not be required to contribute any
amount in excess of the amount by which the amount received by Holder (net of
Selling Expenses) from the sale of the Warrant Shares to which such loss relates
exceeds the amount of any damages which Holder has otherwise been required to
pay by reason of such untrue or alleged untrue statement or omission or alleged
omission. No person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation.

                    (v) The obligations of the Company and Holder under this
Section 10(b) shall be in addition to any liability which the Company and Holder
may otherwise have and shall extend, upon the same terms and conditions, to each
person, if any, who controls the Company or Holder within the meaning of the
Act.

         SECTION 11. EXPIRATION DATE. This Warrant shall expire and shall be
wholly void and have no effect after 5:00 p.m. (San Francisco time) on the date
(the "Expiration Date") which is the earlier of (a) the fifth anniversary of the
date hereof, or (b) the closing date of a merger or consolidation of the Company
with or into any other entity, including a reverse triangular merger involving
the Company (other than a merger or consolidation in which the Holders of the
voting power of the Company immediately prior to such consolidation or merger
hold a majority of the surviving or resulting entity immediately following such
consolidation or merger), provided that, if the last day on which this Warrant
may be exercised, or on which it may be exercised at a particular Exercise
Price, is a Sunday or a legal holiday or a day on which banking institutions
doing business in the city of San Francisco are authorized by law to close, this
Warrant may be exercised prior to 5:00 p.m. (San Francisco time) on the next
succeeding full business day with the same force and effect and at the same
Exercise Price as if exercised on such last day specified herein.

         SECTION 12. GOVERNING LAW. This Warrant is delivered in the State of
California and shall be construed and enforced in accordance with, and the
rights of the parties shall be governed by, the laws of that State.

                                      10.
<PAGE>   11

         SECTION 13. MODIFICATION AND WAIVER. Neither this Warrant nor any term
hereof may be amended, waived, discharged or terminated other than by an
instrument in writing signed by the Company and by the Holder hereof.

         SECTION 14. NOTICES. Any notice, request or other document required or
permitted to be given or delivered to the Holder hereof or the Company shall be
delivered or shall be sent by certified mail, postage prepaid, to each such
Holder at its address as shown on the books of the Company or to the Company at
the address indicated therefor in the first paragraph of this Warrant.

         SECTION 15. DESCRIPTIVE HEADINGS. The description headings of the
several sections and paragraphs of this Warrant are inserted for convenience
only and do not constitute a part of this Warrant.

         SECTION 16. ENTIRE AGREEMENT. This Warrant constitutes the entire
agreement between the parties pertaining to the subject matter herein and
supersedes all prior and contemporaneous agreements, representation and
undertakings of the parties.

         IN WITNESS WHEREOF, the Company has duly caused this Warrant to be
signed by its duly authorized officer and to be dated as of October 13, 2000.

                                       AVIRON

                                       By: /s/ C. Boyd Clarke
                                           ---------------------
                                           C. Boyd Clarke
                                           President and Chief Executive Officer

                                      11.
<PAGE>   12

                                SUBSCRIPTION FORM

         THE UNDERSIGNED, holder of this Warrant, (1) hereby irrevocably elects
to exercise the right of purchase represented by this Warrant for, and to
purchase thereunder, ________________ full Warrant Shares of the Common Stock of
Aviron provided for therein, (2) makes payment in full of the purchase price of
such Warrant Shares, in the amount of $_____________, and (3) requests that
certificates for such Warrant Shares be issued in the name of:

        ----------------------------------------------------------------
                         (Please print name and address)

        ----------------------------------------------------------------
           (Please insert social security or other identifying number)

Dated:_______________________________________________

Signature:____________________________________________________

By:___________________________________________________________

<PAGE>   13

                                 ASSIGNMENT FORM

                                                           Dated _________, 20__

         FOR VALUE RECEIVED, _____________________________________ hereby sells,
assigns and transfers unto ________________________________________________ (the
"Assignee"),____________________________________________________________________
                        (please type or print in block letters)

________________________________________________________________________________
                                (insert address)

its right to purchase up to ________ shares of Common Stock of AVIRON
represented by this Warrant and does hereby irrevocably constitute and appoint
____________________________ Attorney, to transfer the same on the books of the
Company, with full power of substitution in the premises.

         Signature__________________________________

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