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                                                                     EXHIBIT 4.1

                              AETHER SYSTEMS, INC.
                           ACQUISITIONS INCENTIVE PLAN

                        Effective as of December 15, 2000

PURPOSE               Aether Systems, Inc., a Delaware corporation (the
                      "Company"), wishes to recruit, reward, and retain
                      employees and other service providers. To further these
                      objectives, particularly with respect to acquired
                      companies, the Company hereby sets forth the Aether
                      Systems, Inc. Acquisitions Incentive Plan (the "Plan"),
                      effective as of December 15, 2000 (the "Effective Date")
                      to provide options ("Options") or direct grants ("Stock
                      Grants" and, together with the Options, "Awards") to
                      employees and other service providers of the Company and
                      its Related Companies with respect to shares of the
                      Company's common stock (the "Common Stock").

PARTICIPANTS          All Employees (except directors and Officers of the
                      Company and any Eligible Affiliates) are eligible for
                      Awards under this Plan. Eligible Employees become
                      "optionees" when the Administrator grants them an option
                      under this Plan or "recipients" when they receive a Stock
                      Grant. (Optionees and recipients are together referred to
                      as "participants.") The Administrator may also grant
                      Awards to consultants and certain other service providers.
                      The term participant also includes, where appropriate, a
                      person authorized to exercise or retain an Award in place
                      of the original recipient.

                      Employee means any person employed as a common law
                      employee of the Company or a Related Company.

                      Officer means any person who would be treated as an
                      executive officer for purposes of securities reporting.

ADMINISTRATOR         The Administrator will be the Compensation Committee of
                      the Board of Directors, unless the Board either specifies
                      another committee of the Board or acts under the Plan as
                      though it were the Compensation Committee.

                      The Administrator is responsible for the general operation
                      and administration of the Plan and for carrying out its
                      provisions and has full discretion in interpreting and
                      administering the provisions of the Plan. Subject to the
                      express provisions of the Plan, the Administrator may
                      exercise such powers and authority of the

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                      Board as the Administrator may find necessary or
                      appropriate to carry out its functions. The Administrator
                      may delegate its functions (other than those described in
                      the GRANTING OF AWARDS section) to officers or other
                      Employees of the Company.

                      The Administrator's powers will include, but not be
                      limited to, the power to amend, waive, or extend any
                      provision or limitation of any Option. The Administrator
                      may act through meetings of a majority of its members or
                      by unanimous consent.

                      The Administrator may also make Stock Grants (with any or
                      no restrictions) as a bonus or other incentive or to grant
                      such stock or other awards in lieu of Company obligations
                      to pay cash under other plans or compensatory
                      arrangements, including any deferred compensation plans or
                      as a replacement for other awards.

GRANTING OF           Subject to the terms of the Plan, the Administrator will,
AWARDS                in its sole discretion, determine

                             the participants who receive Awards,

                             the terms of such Awards,

                             the schedule for exercisability or
                             nonforfeitability (including any requirements that
                             the participant or the Company satisfy performance
                             criteria),

                             the time and conditions for expiration of the
                             Awards, and

                             the form of payment due upon exercise, if any.

                      The Administrator's determinations under the Plan need not
                      be uniform and need not consider whether possible
                      participants are similarly situated.

                      All Options newly granted to Employees must be
                      nonqualified stock options ("NQSOs"). If the Company
                      wishes to award "incentive stock options" ("ISOs") within
                      the meaning of Section 422 of the Internal Revenue Code of
                      1986 (the "Code"), or the corresponding provision of any
                      subsequently enacted tax statute, the shareholders must
                      approve making such awards, except as provided under
                      Substitutions.

                      The Administrator may impose such conditions on or charge
                      such price for the Stock Grants as it considers
                      appropriate.

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        Substitutions        The Administrator may also grant Awards in
                             substitution for options or other equity interests
                             held by individuals who become Employees of the
                             Company or of a Related Company as a result of the
                             Company's or Related Company's acquiring or merging
                             with the individual's employer or acquiring its
                             assets. In addition, the Administrator may provide
                             for the Plan's assumption of awards granted outside
                             the Plan to persons who would have been eligible
                             under the terms of the Plan to receive an Award,
                             including both persons who provided services to any
                             acquired company or business and persons who
                             provided services to the Company or any Related
                             Company. If appropriate to conform the Awards to
                             the interests for which they are substitutes, the
                             Administrator may grant substitute Awards under
                             terms and conditions (including Exercise Price)
                             that vary from those the Plan otherwise requires
                             and may grant ISOs to replace ISOs that were
                             approved by the acquired company's shareholders.

DATE OF GRANT         The Date of Grant will be the date the Administrator
                      grants an Award to a person, as specified in the Plan or
                      in the Administrator's minutes or other written evidence
                      of action.

EXERCISE PRICE        The Exercise Price is the value of the consideration that
                      a participant must provide in exchange for one share of
                      Common Stock. The Administrator will determine the
                      Exercise Price under each Award and may set the Exercise
                      Price without regard to the Exercise Price of any other
                      Awards granted at the same or any other time. The Company
                      may use the consideration it receives from the participant
                      for general corporate purposes.

                      The Exercise Price per share for NQSOs may not be less
                      than 85% of the Fair Market Value of a share on the Date
                      of Grant.

                      The Administrator may satisfy any state law requirements
                      regarding adequate consideration for Restricted Stock
                      Grants by (i) issuing Common Stock held as treasury stock
                      or (ii) charging the recipients at least the par value for
                      the shares covered by the Restricted Stock Grant. The
                      Administrator may designate that a recipient may satisfy
                      (ii) either by direct payments or by the Administrator's
                      withholding from other payments due to the recipient.

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        FAIR MARKET          Fair Market Value (on the date of Grant) of a share
        VALUE                of Common Stock for purposes of the Plan will be
                             determined as follows:

                                    if the Common Stock trades on a national
                                    securities exchange, the closing sale price
                                    on that date;

                                    if the Common Stock does not trade on any
                                    such exchange, the closing sale price as
                                    reported by the National Association of
                                    Securities Dealers, Inc. Automated Quotation
                                    System ("Nasdaq") for such date;

                                    if no such closing sale price information is
                                    available, the average of the closing bid
                                    and asked prices that Nasdaq reports for
                                    such date;

                                    if there are no such closing bid and asked
                                    prices, the average of the closing bid and
                                    asked prices as reported by any other
                                    commercial service for such date; or

                                    if the Company has no publicly-traded stock,
                                    the Administrator will determine the Fair
                                    Market Value for purposes of the Plan using
                                    any measure of value it determines in good
                                    faith to be appropriate;

                             For any date that is not a trading day, the Fair
                             Market Value of a share of Common Stock for such
                             date will be determined by using the closing sale
                             price or the average of the closing bid and asked
                             prices, as appropriate, for the immediately
                             preceding trading day. The Administrator can
                             substitute a particular time of day or other
                             measure of "closing sale price" or "bid and asked
                             prices" if appropriate because of changes in
                             exchange or market procedures.

                             The Administrator has sole discretion to determine
                             the Fair Market Value for purposes of this Plan,
                             and all Awards are conditioned on the participants'
                             agreement that the Administrator's determination is
                             conclusive and binding even though others might
                             make a different and also reasonable determination.

EXERCISABILITY        The Administrator will determine the times and conditions
                      for exercise or retention of each Award.

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                      Awards will become exercisable or nonforfeitable at such
                      times and in such manner as the Administrator determines
                      and the Award Agreement, if any, indicates; provided,
                      however, that the Administrator may, on such terms and
                      conditions as it determines appropriate, accelerate the
                      time at which the participant may exercise any portion of
                      an Award or at which restrictions on Stock Grants lapse.
                      For Stock Grants, "exercise" refers to acceptance of the
                      Award or lapse of restrictions, as appropriate in context.

                      If the Administrator does not specify otherwise, Options
                      will become exercisable and restrictions on Stock Grants
                      will lapse as to 25% per year on each anniversary of the
                      Date of Grant, so long as the participant remains employed
                      or continues his relationship as a service provider, and
                      will expire as of the tenth anniversary of the Date of
                      Grant (unless they expire earlier under the Plan or the
                      Award Agreement). The Administrator has the sole
                      discretion to determine that a change in service-providing
                      relationship eliminates any further service credit on the
                      exercise schedule.

                      No portion of an Award that is unexercisable at a
                      participant's termination of service-providing
                      relationship (for any reason) will thereafter become
                      exercisable (and the participant will immediately forfeit
                      any unexercisable portions at his termination of
                      service-providing relationship), unless the Award
                      Agreement provides otherwise, either initially or by
                      amendment.

        CHANGE OF     Upon a Change of Control (as defined below), Awards will
        CONTROL       only become fully exercisable if the Award Agreement
                      provides for such acceleration. Any Awards granted to a
                      participant in replacement of other awards not under this
                      Plan will not become fully exercisable upon a Change of
                      Control unless the plan under which the awards were
                      originally granted specifically provided for such
                      acceleration or unless the Administrator provided for such
                      acceleration in replacing the awards. A Change of Control
                      for this purpose means the occurrence of any one or more
                      of the following events:

                                    (i) sale of all or substantially all of the
                                    assets of the Company to one or more
                                    individuals, entities, or groups (other than
                                    an Excluded Owner);

                                    (ii) complete or substantially complete
                                    dissolution or liquidation of the Company;

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                                    (iii) a person, entity, or group (other than
                                    an Excluded Owner) acquires or attains
                                    ownership of at least 80% of the undiluted
                                    total voting power of the Company's
                                    then-outstanding securities eligible to vote
                                    to elect members of the Board ("Company
                                    Voting Securities");

                                    (iv) completion of a merger or consolidation
                                    of the Company with or into any other entity
                                    (other than an Excluded Owner) unless the
                                    holders of the Company Voting Securities
                                    outstanding immediately before such
                                    completion, together with any trustee or
                                    other fiduciary holding securities under a
                                    Company benefit plan, retain control because
                                    they hold securities that represent
                                    immediately after such merger or
                                    consolidation more than 20% of the combined
                                    voting power of the then outstanding voting
                                    securities of either the Company or the
                                    other surviving entity or its ultimate
                                    parent

                                    (v) the individuals who constitute the Board
                                    immediately before a proxy contest cease to
                                    constitute at least a majority of the Board
                                    (excluding any Board seat that is vacant or
                                    otherwise unoccupied) immediately following
                                    the proxy contest; or

                                    (vi) during any two year period, the
                                    individuals who constitute the Board at the
                                    beginning of the period (the "Incumbent
                                    Directors") cease for any reason to
                                    constitute at least a majority of the Board
                                    (excluding any Board seat that is vacant or
                                    otherwise unoccupied), provided that any
                                    individuals that a majority of Incumbent
                                    Directors approve for service on the Board
                                    are treated as Incumbent Directors.

                             An "Excluded Owner" consists of the Company, any
                             Related Company, any Company benefit plan, or any
                             underwriter temporarily holding securities for an
                             offering of such securities.

                             Even if other tests are met, a Change of Control
                             has not occurred under any circumstance in which
                             the Company files for bankruptcy protection or is
                             reorganized following a

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                             bankruptcy filing. The Administrator may determine
                             that a particular participant's Awards will not
                             become fully exercisable as a result of what the
                             Administrator, in its sole discretion, determines
                             is the participant's insufficient cooperation with
                             the Company with respect to a Change of Control. In
                             addition, the acceleration will not occur if it
                             would prevent use of "pooling of interest"
                             accounting for a reorganization, merger, or
                             consolidation of the Company that the Board
                             approves.

                             The Administrator may allow conditional exercises
                             in advance of the completion of a Change of Control
                             that are then rescinded if no Change of Control
                             occurs. The Administrator may also provide that the
                             accelerations under the Change of Control occur
                             automatically up to six months after the Change of
                             Control.

        SUBSTANTIAL          Upon a Change of Control that is also a Substantial
        CORPORATE            Corporate Change, the Awards will become
        CHANGE               exercisable only as provided under the Change of
                             Control section and the Plan and any unexercised
                             Awards will TERMINATE (after the occurrence of one
                             of the alternatives set forth in the next full
                             paragraph) unless either (i) such termination would
                             prevent use of "pooling of interest" accounting for
                             a reorganization, merger, or consolidation of the
                             Company that the Board approves, (ii) an agreement
                             with a participant provides otherwise, or (iii)
                             provision is made in writing in connection with
                             such transaction for

                                    the assumption or continuation of
                                    outstanding Awards, or

                                    the substitution for such options or grants
                                    of any options or grants covering the stock
                                    or securities of a successor employer
                                    entity, or a parent or subsidiary of such
                                    successor, with appropriate adjustments as
                                    to the number and kind of shares of stock
                                    and prices, in which event the Awards will
                                    continue in the manner and under the terms
                                    so provided.

                             If an Option would otherwise terminate under the
                             preceding sentence and the Administrator considers
                             that the Fair Market Value of the Common Stock as a
                             result of the Substantial Corporate Change exceeds
                             or is likely to exceed

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                             the Exercise Price, the Administrator will either
                             provide that

                                    optionees will have the right, at such time
                                    before the completion of the transaction
                                    causing such termination as the Board or the
                                    Administrator reasonably designates, to
                                    exercise any unexercised portions of the
                                    Option, including those portions that the
                                    Change of Control will make exercisable, or

                                    cause the Company, or agree to allow the
                                    successor, to cancel each Option after
                                    payment to the optionee of an amount in
                                    cash, cash equivalents, or successor equity
                                    interests substantially equal to the Fair
                                    Market Value under the transaction minus the
                                    Exercise Price for the shares covered by the
                                    Option (and, where the Board or the
                                    Administrator determines it is appropriate,
                                    any required tax withholdings).

                             The Administrator may allow conditional exercises
                             in advance of the completion of a Substantial
                             Corporate Change that are then rescinded if no
                             Substantial Corporate Change occurs.

                             The Board or other Administrator may take any
                             actions described in the Substantial Corporate
                             Changes section, without any requirement to seek
                             optionee consent.

                             A Substantial Corporate Change means any of the
                             following events:

                                    a sale as described in clause (i) under
                                    CHANGE OF CONTROL,

                                    a dissolution or liquidation as described in
                                    clause (ii),

                                    an ownership change as described in clause
                                    (iii), but with the percentage ownership
                                    increased to 100%

                                    merger, consolidation, or reorganization of
                                    the Company with or into one or more
                                    corporations or other entities in which the
                                    Company is not the surviving entity, other
                                    than a transaction intended primarily to
                                    change the Company's state of

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                                    incorporation or that satisfies clause (iv)
                                    under Change of Control, or

                                    any other transaction (including a merger or
                                    reorganization in which the Company
                                    survives) approved by the Board that results
                                    in any person or entity (other than an
                                    Excluded Owner) owning 100% of Company
                                    Voting Securities.

LIMITATION ON         An Option granted to an Employee as an ISO will be an ISO
ISOs                  only to the extent that the aggregate Fair Market Value
                      (determined at the Date of Grant) of the stock with
                      respect to which ISOs are exercisable for the first time
                      by the optionee during any calendar year (under the Plan
                      and all other plans of the Company and its subsidiary
                      corporations, within the meaning of Code Section 422(d)),
                      does not exceed $100,000. This limitation applies to
                      Options in the order in which such Options were granted.
                      If, by design or operation, the Option exceeds this limit,
                      the excess will be treated as an NQSO.

METHOD OF             To exercise any exercisable portion of an Option, the
EXERCISE              optionee must:

                             Deliver notice of exercise to the Secretary of the
                             Company (or to whomever the Administrator
                             designates), in a form complying with any rules the
                             Administrator may issue, signed or otherwise
                             authenticated by the optionee, and specifying the
                             number of shares of Common Stock underlying the
                             portion of the Option the optionee is exercising;

                             Pay the full Exercise Price by cash or a cashier's
                             or certified check for the shares of Common Stock
                             with respect to which the Option is being
                             exercised, unless the Administrator consents to
                             another form of payment (which could include loans
                             from the Company or the use of Common Stock); and

                             Deliver to the Administrator such representations
                             and documents as the Administrator, in its sole
                             discretion, may consider necessary or advisable.

                      Payment in full of the Exercise Price need not accompany
                      the written notice of exercise if the exercise complies
                      with a previously-approved cashless exercise method,
                      including, for example, that the notice directs that the
                      stock certificates (or other indicia of ownership) for the
                      shares issued upon the exercise be

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                      delivered to a licensed broker acceptable to the Company
                      as the agent for the individual exercising the Option and
                      at the time the stock certificates (or other indicia) are
                      delivered to the broker, the broker will tender to the
                      Company cash or cash equivalents acceptable to the Company
                      and equal to the Exercise Price and any required
                      withholding taxes.

                      If the Administrator agrees to allow an optionee to pay
                      through tendering shares of Common Stock to the Company,
                      the individual can only tender stock he has held for at
                      least six months at the time of surrender. Shares of stock
                      offered as payment will be valued, for purposes of
                      determining the extent to which the optionee has paid the
                      Exercise Price, at their Fair Market Value on the date of
                      exercise. The Administrator may also, in its discretion,
                      accept attestation of ownership of Common Stock and issue
                      a net number of shares upon Option exercise, or have a
                      broker tender to the Company cash equal to the exercise
                      price and any withholding taxes.

AWARD                 No one may exercise an Option more than ten years after
EXPIRATION            its Date of Grant. A participant will immediately forfeit
                      and can never exercise or retain any portion of an Award
                      that is unexercisable or nonforfeitable at his termination
                      of service-providing relationship (for any reason), unless
                      the Award Agreement provides otherwise, either initially
                      or by amendment. Unless the Award Agreement provides
                      otherwise, either initially or by amendment, no one may
                      exercise otherwise exercisable portions of an Option after
                      the first to occur of:

        EMPLOYMENT           The 90th day after the date of termination of
        TERMINATION          service-providing relationship (other than for
                             death or Disability), where termination of
                             service-providing relationship means the time when
                             the employer-employee or other service-providing
                             relationship between the individual and the Company
                             (and all Related Companies) ends for any reason.
                             The Administrator may provide that Options
                             terminate immediately upon termination of
                             service-providing relationship for "cause" under an
                             employee's employment or consultant's services
                             agreement or under another definition specified in
                             the Award Agreement. Unless the Award Agreement or
                             the Administrator provides otherwise, termination
                             of employment does not include instances in which
                             the Company immediately rehires a common law
                             employee as an independent contractor. The
                             Administrator, in its sole discretion, will
                             determine all questions of whether particular
                             terminations or leaves of

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                                                     Acquisitions Incentive Plan
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                             absence are terminations of employment and may
                             decide to suspend the exercise or forfeiture
                             schedule during a leave rather than to terminate
                             the Award Unless the Award Agreement or the
                             Administrator provides otherwise, terminations of
                             service-providing relationship include situations
                             in which the optionee's employer ceases to be
                             related to the Company closely enough to be a
                             Related Company for new grants.

        GROSS MISCONDUCT     For the Company's termination of the participant's
                             service-providing relationship as a result of the
                             participant's Gross Misconduct, the time of such
                             termination. For purposes of this Plan, "Gross
                             Misconduct" means the participant has

                                    committed fraud, misappropriation,
                                    embezzlement, or willful misconduct that has
                                    resulted or is likely to result in material
                                    harm to the Company or a Related Company;

                                    committed or been indicted for or convicted
                                    of, or pled guilty or no contest to, any
                                    misdemeanor (other than for minor
                                    infractions or traffic violations) involving
                                    fraud, breach of trust, misappropriation, or
                                    other similar activity or otherwise relating
                                    to the Company or any Related Company, or
                                    any felony; or

                                    committed an act of gross negligence or
                                    otherwise acted with willful disregard for
                                    the Company's or a Related Company's best
                                    interests in a manner that has resulted or
                                    is likely to result in material harm to the
                                    Company or a Related Company.

                             If the participant has a written employment or
                             other agreement in effect at the time of his
                             termination that specifies "cause" for termination,
                             "Gross Misconduct" for purposes of his termination
                             will refer to "cause" under the employment or other
                             agreement, rather than to the foregoing definition.

        DISABILITY           For disability, the earlier of (i) the first
                             anniversary of the participant's termination of
                             employment for disability and (ii) 60 days after
                             the participant no longer has a disability, where
                             "disability" means the inability to engage in any
                             substantial gainful activity because of any
                             medically determinable physical or mental
                             impairment that can be expected to result in death
                             or that has lasted or can be

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                                                     Acquisitions Incentive Plan
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                             expected to last for a continuous period of not
                             less than 12 months; or

        DEATH                The date 12 months after the participant's death.

                      If exercise is permitted after termination of
                      service-providing relationship, the Award will
                      nevertheless expire as of the date that the former service
                      provider violates any covenant not to compete or other
                      post-employment covenant in effect between the Company or
                      a Related Company and the former employee or other service
                      provider. In addition, an optionee who exercises an Option
                      more than 90 days after termination of employment with the
                      Company and/or Eligible Affiliates will only receive ISO
                      treatment to the extent the law permits, and becoming or
                      remaining an employee of another related company (that is
                      not an Eligible Affiliate) or an independent contractor
                      will not prevent loss of ISO status because of the formal
                      termination of employment.

                      Nothing in this Plan extends the term of an Option beyond
                      the tenth anniversary of its Date of Grant, nor does
                      anything in this AWARD EXPIRATION section make an Option
                      exercisable or Stock Grant nonforfeitable that has not
                      otherwise become exercisable or nonforfeitable, unless the
                      Administrator specifies otherwise.

AWARD                 Award Agreements (which could be certificates) will set
AGREEMENT             forth the terms of each Award and will include such terms
                      and conditions, consistent with the Plan, as the
                      Administrator may determine are necessary or advisable. To
                      the extent the agreement is inconsistent with the Plan,
                      the Plan will govern. The Award Agreements may contain
                      special rules.

PUT AND CALL          The Administrator may provide in Award Agreements or other
RIGHTS                agreements that the Company has the right (or obligation)
                      to purchase outstanding Awards, or the shares received
                      from exercising an Option, under certain circumstances,
                      including termination of service-providing relationship
                      for any reason or death and may provide for rights of
                      first refusal. The Administrator may distinguish between
                      unexercisable and exercisable Awards.

STOCK SUBJECT         Except as adjusted below under CORPORATE CHANGES, the
TO PLAN               aggregate number of shares of Common Stock that may be
                      issued in Awards may not exceed 1,900,000 shares, and the
                      maximum number of ISOs that may be issued may not exceed
                      the number approved by the shareholders of the Company (or
                      by an acquired company's shareholders for ISOs assumed by
                      this Plan). Shares used as payment for the Exercise Price
                      or any required

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                      withholdings will be added back to the totals available
                      for issuance.

                      The Common Stock will come from either authorized but
                      unissued shares or from previously issued shares that the
                      Company reacquires, including shares it purchases on the
                      open market or holds as treasury shares. If any Award
                      expires, is canceled, or terminates for any other reason,
                      the shares of Common Stock available under that Award will
                      again be available for the granting of new Awards.

                      No adjustment will be made for a dividend or other right
                      for which the record date precedes the date of exercise.

                      The optionee will have no rights of a stockholder with
                      respect to the shares of stock subject to an Option except
                      to the extent that the Company has issued certificates
                      for, or otherwise confirmed ownership of, such shares upon
                      the exercise of the Option.

                      The Company will not issue fractional shares pursuant to
                      the exercise of an Option, unless the Administrator
                      determines otherwise, but the Administrator may, in its
                      discretion, direct the Company to make a cash payment in
                      lieu of fractional shares.

PERSON WHO            During the participant's lifetime and except as provided
MAY EXERCISE          under TRANSFERS, ASSIGNMENTS, AND PLEDGES, only the
                      participant or his duly appointed guardian or personal
                      representative may exercise the Options or hold the
                      forfeitable Stock Grants. After his death, his personal
                      representative or any other person authorized under a will
                      or under the laws of descent and distribution may exercise
                      any then exercisable portion of an Option. If someone
                      other than the original recipient seeks to exercise any
                      portion of an Option, the Administrator may request such
                      proof as it may consider necessary or appropriate of the
                      person's right to exercise the Option.

ADJUSTMENTS           Subject to any required action by the Company (which it
UPON CHANGES          agrees to promptly take) or its stockholders, and subject
IN CAPITAL            to the provisions of applicable corporate law, if, after
STOCK                 the Date of Grant of an Option,

                             the outstanding shares of Common Stock increase or
                             decrease or change into or are exchanged for a
                             different number or kind of security because of any
                             recapitalization, reclassification, stock split,
                             reverse stock split, combination of shares,
                             exchange of shares, stock dividend, or other
                             distribution payable in capital stock, or

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                             some other increase or decrease in such Common
                             Stock occurs without the Company's receiving
                             consideration (excluding, unless the Administrator
                             determines otherwise, stock repurchases),

                      the Administrator must make a proportionate and
                      appropriate adjustment in the number of shares of Common
                      Stock underlying each Option, so that the proportionate
                      interest of the participant immediately following such
                      event will, to the extent practicable, be the same as
                      immediately before such event. (This adjustment does not
                      apply to Common Stock that the optionee has already
                      purchased, nor to Stock Grants, each of which are subject
                      to the adjustment applicable to Common Stock.) Unless the
                      Administrator determines another method would be
                      appropriate, any such adjustment to an Option will not
                      change the total price with respect to shares of Common
                      Stock underlying the unexercised portion of the Option but
                      will include a corresponding proportionate adjustment in
                      the Option's Exercise Price. The Board or other
                      Administrator may take any actions described in this
                      section without any requirement to seek optionee consent.

                      The Administrator will make a commensurate change to the
                      maximum number and kind of shares provided in the STOCK
                      SUBJECT TO PLAN section.

                      Any issue by the Company of any class of preferred stock,
                      or securities convertible into shares of common or
                      preferred stock of any class, will not affect, and no
                      adjustment by reason thereof will be made with respect to,
                      the number of shares of Common Stock subject to any Award
                      or the Exercise Price except as this ADJUSTMENTS section
                      specifically provides. The grant of an Award under the
                      Plan will not affect in any way the right or power of the
                      Company to make adjustments, reclassifications,
                      reorganizations or changes of its capital or business
                      structure, or to merge or to consolidate, or to dissolve,
                      liquidate, sell, or transfer all or any part of its
                      business or assets.

RELATED               Employees of Eligible Affiliates will be entitled to
COMPANY               participate in the Plan, except as otherwise designated by
EMPLOYEES             the Board or the Administrator.

                      Eligible Affiliate means each of the Related Companies,
                      except as the Administrator otherwise specifies. For ISO
                      grants, "Related Company" means any corporation in an
                      unbroken chain of corporations including the Company if,
                      at the time an Option is granted to a Participant under
                      the Plan, each corporation (other

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                                                     Acquisitions Incentive Plan
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                      than the last corporation in the unbroken chain) owns
                      stock possessing 50% or more of the total combined voting
                      power of all classes of stock in another corporation in
                      such chain. Related Company also includes a single-member
                      limited liability company included within the chain
                      described in the preceding sentence. The Board or the
                      Administrator may use a different definition of Related
                      Company for NQSOs and may include other forms of entity at
                      the same level of equity relationship (or such other level
                      as the Board or the Administrator specifies).

LEGAL                 The Company will not issue any shares of Common Stock
COMPLIANCE            under an Award until all applicable requirements imposed
                      by Federal and state securities and other laws, rules, and
                      regulations, and by any applicable regulatory agencies or
                      stock exchanges, have been fully met. To that end, the
                      Company may require the participant to take any reasonable
                      action to comply with such requirements before issuing
                      such shares, including compliance with any Company
                      black-out periods or trading restrictions. No provision in
                      the Plan or action taken under it authorizes any action
                      that Federal or state laws otherwise prohibit.

                      The Plan is intended to conform to the extent necessary
                      with all provisions of the Securities Act of 1933
                      ("Securities Act") and the Securities Exchange Act of 1934
                      and all regulations and rules the Securities and Exchange
                      Commission issues under those laws. Notwithstanding
                      anything in the Plan to the contrary, the Administrator
                      must administer the Plan, and Awards may be granted and
                      exercised, only in a way that conforms to such laws,
                      rules, and regulations. To the extent permitted by
                      applicable law, the Plan and any Awards will be treated as
                      amended to the extent necessary to conform to such laws,
                      rules, and regulations.

PURCHASE FOR          Unless a registration statement under the Securities Act
INVESTMENT            covers the share of Common Stock a participant receives
AND OTHER             upon exercising his Award, the Administrator may require,
RESTRICTIONS          at the time of such exercise, that the participant agree
                      in writing to acquire such shares for investment and not
                      for public resale or distribution, unless and until the
                      shares subject to the Award are registered under the
                      Securities Act. Unless the shares are registered under the
                      Securities Act, the participant must acknowledge:

                             that the shares purchased on exercise of the Award
                             are not so registered,

                             that the participant may not sell or otherwise
                             transfer the shares unless

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                                                     Acquisitions Incentive Plan
                                                                         Page 15
<PAGE>   16

                                    such sale or transfer complies with all
                                    applicable laws, rules, and regulations,
                                    including all applicable Federal and state
                                    securities laws, rules, and regulations, and
                                    either

                                    the shares have been registered under the
                                    Securities Act in connection with the sale
                                    or transfer thereof, or

                                    counsel satisfactory to the Company has
                                    issued an opinion satisfactory to the
                                    Company that the sale or other transfer of
                                    such shares is exempt from registration
                                    under the Securities Act.

                      Additionally, the Common Stock, when issued upon the
                      exercise of an Award, will be subject to any other
                      transfer restrictions, rights of first refusal, and rights
                      of repurchase set forth in or incorporated by reference
                      into other applicable documents, including the Award
                      Agreements, or the Company's articles or certificate of
                      incorporation, by-laws, or generally applicable
                      stockholders' agreements.

                      The Administrator may, in its sole discretion, take
                      whatever additional actions it deems appropriate to comply
                      with such restrictions and applicable laws, including
                      placing legends on certificates and issuing stop- transfer
                      orders to transfer agents and registrars.

TAX WITHHOLDING       The participant must satisfy all applicable Federal,
                      state, and local income and employment tax withholding
                      requirements before the Company will deliver stock
                      certificates or otherwise recognize ownership upon the
                      exercise of an Award. The Company may decide to satisfy
                      the withholding obligations through additional withholding
                      on salary or wages. If the Company does not or cannot
                      withhold from other compensation, the participant must pay
                      the Company, with a cashier's check or certified check,
                      the full amounts, if any, required for withholding.
                      Payment of withholding obligations is due before the
                      Company will issue any share on exercise, or, if the
                      Administrator so requires, at the same time as is payment
                      of the Exercise Price. If the Administrator so determines,
                      the participant may instead satisfy the withholding
                      obligations by directing the Company to retain shares from
                      the Award exercise, by tendering previously owned shares,
                      or by attesting to his ownership of shares (with the
                      distribution of net shares), or by having a broker tender
                      to the Company cash equal to the withholding taxes.
                      Without any requirement to seek an optionee's

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                                                     Acquisitions Incentive Plan
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<PAGE>   17

                      consent, the Company may require the optionee to use one
                      or more specified brokerage firms to exercise and to hold
                      shares received from Awards until the later of one year
                      after exercise or two years after the Date of Grant for
                      Options or the lapse of all forfeiture provisions for
                      Stock Grants.

TRANSFERS,            Unless the Administrator otherwise approves in advance in
ASSIGNMENTS,          writing for estate planning or other purposes, an Award
AND PLEDGES           may not be assigned, pledged or otherwise transferred in
                      any way, whether by operation of law or otherwise or
                      through any legal or equitable proceedings (including
                      bankruptcy), by the participant to any person, except by
                      will or by operation of applicable laws of descent and
                      distribution. If necessary to comply with Rule 16b-3, the
                      participant may not transfer or pledge shares of Common
                      Stock acquired upon exercise of an Award until at least
                      six months have elapsed from (but excluding) the Date of
                      Grant, unless the Administrator approves otherwise in
                      advance in writing. The Administrator may, in its
                      discretion, expressly provide that a participant may
                      transfer his Award, without receiving consideration, to
                      (i) members of his immediate family (children,
                      grandchildren, or spouse), (ii) trusts for the benefit of
                      such family members, or (iii) partnerships whose only
                      partners are such family members.

AMENDMENT OR          The Board or Compensation Committee may amend, suspend,
TERMINATION           or, terminate the Plan at any time without the consent of
OF PLAN AND           the participants; or their beneficiaries; provided,
OPTIONS               however, that such actions are consistent with this
                      section. Except as required by law or by the SUBSTANTIAL
                      CORPORATE CHANGES section, the Administrator may not,
                      without the participant's or beneficiary's consent, modify
                      the terms and conditions of an Award so as to materially
                      adversely affect the participant. No amendment,
                      suspension, or termination of the Plan will, without the
                      participant's or beneficiary's consent, terminate or
                      materially adversely affect any right or obligations under
                      any outstanding Awards, except as provided in the
                      SUBSTANTIAL CORPORATE CHANGES Section.

PRIVILEGES OF         No participant and no beneficiary or other person claiming
STOCK                 under or through such optionee will have any right, title,
OWNERSHIP             or interest in or to any shares of Common Stock allocated
                      or reserved under the Plan or subject to any Award except
                      as to such shares of Common Stock, if any, already issued
                      to such participant.

EFFECT ON             Whether receiving or exercising an Award causes the
                      participant

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                                                     Acquisitions Incentive Plan
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<PAGE>   18

OTHER PLANS           to accrue or receive additional benefits under any pension
                      or other plan is governed solely by the terms of such
                      other plan.

LIMITATIONS ON        Notwithstanding any other provisions of the Plan,
LIABILITY             no individual acting as a director, officer, other
                      employee, or agent of the Company will be liable to any
                      participant, former participant, spouse, beneficiary, or
                      any other person for any claim, loss, liability, or
                      expense incurred in connection with the Plan, nor will
                      such individual be personally liable because of any
                      contract or other instrument he executes in such other
                      capacity. The Company will indemnify and hold harmless
                      each director, officer, other employee, or agent of the
                      Company to whom any duty or power relating to the
                      administration or interpretation of the Plan has been or
                      will be delegated, against any cost or expense (including
                      attorneys' fees) or liability (including any sum paid in
                      settlement of a claim with the Board's approval) arising
                      out of any act or omission to act concerning this Plan
                      unless arising out of such person's own fraud or bad
                      faith.

NO EMPLOYMENT         Nothing contained in this Plan constitutes an employment
CONTRACT              contract between the Company and the optionees. The Plan
                      does not give any participant any right to be retained in
                      the Company's employ, nor does it enlarge or diminish the
                      Company's right to end the participant's employment or
                      other relationship with the Company.

APPLICABLE LAW        The laws of the State of Delaware (other than its choice
                      of law provisions) govern this Plan and its
                      interpretation.

DURATION OF           Unless the Board extends the Plan's term, the
PLAN                  Administrator may not grant Options after December 14,
                      2010. The Plan will then terminate but will continue to
                      govern unexercised and unexpired Options.

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                                                            Aether Systems, Inc.
                                                     Acquisitions Incentive Plan
                                                                         Page 18<PAGE>   1

                                                                   EXHIBIT 10.01

                 AMENDMENT TO 1997 STOCK OPTION PLAN, AS AMENDED

On March 16, 2000, the Board of Directors of the Company approved amending the
above-referenced plan to increase the number of shares of common stock, par
value $.10 per share, of the Company available for grant as stock options by
1,000,000 shares. All other terms of the plan remained unchanged.

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