Exhibit 4.1

EXECUTION VERSION

WARRANT AGREEMENT

between

UNDER ARMOUR, INC.

and

NFL PROPERTIES LLC

Dated as of

August 3, 2006

i

ii

WARRANT AGREEMENT (this “ Agreement ”), dated as of August 3, 2006, between Under Armour, Inc., a Maryland corporation (“ Under Armour ”), and NFL Properties LLC, a Delaware limited liability company (“ NFL Properties ”). Each of Under Armour and NFL Properties is referred to individually as a “Party” and collectively as the “Parties.”

W I T N E S S E T H :

WHEREAS, Under Armour and NFL Properties have entered into a Promotional Rights Agreement, dated August 3, 2006 (the “ Promotional Rights Agreement ”), pursuant to which (i) NFL Properties has granted to Under Armour licensing rights for certain of Under Armour’s products and (ii) Under Armour has agreed to issue certain warrants to purchase shares of Class A common stock, par value $0.0003-1/3 per share, of Under Armour (the “ Common Shares ”), to NFL Properties;

NOW, THEREFORE, in consideration of the premises and the mutual representations, warranties, covenants and agreements contained in this Agreement, the Parties agree as follows:

ARTICLE I

INTERPRETATION

1.01 Definitions . Capitalized words used in this Agreement shall have the meanings and definitions set forth in Schedule 1.01 (such meanings to be equally applied to both the singular and plural forms of the terms defined).

1.02 General Interpretive Principles . The headings contained in this Agreement or in any Exhibit or Schedule hereto and in the table of contents are for reference purposes only and shall not affect in any way the meaning or interpretation of the Agreement. When a reference is made herein to a Section, Article, Paragraph, Exhibit, Schedule, Preamble or Recitals, such reference shall be to a Section, Article or Paragraph of, or an Exhibit, Schedule, Preamble or Recital to, this Agreement unless otherwise indicated. Whenever used in this Agreement, except as otherwise expressly provided or unless the context otherwise requires, (i) any noun or pronoun shall be deemed to include the plural as well as the singular and to cover all genders, (ii) the terms “include,” “includes” and “including” shall be deemed to be followed by the words “without limitation” and (iii) the words “hereof,” “herein” and similar words refer to this Agreement as a whole (including the Exhibits and Schedules).

ARTICLE II

GRANT OF WARRANTS

2.01 Issuance of Warrants . Upon the terms and subject to the conditions set forth in this Agreement, and in reliance upon the representations and warranties set forth in this Agreement, upon the execution and delivery of the parties thereto of the Promotional Rights Agreement, Under Armour will issue and deliver to NFL Properties, (i) 240,000 warrants in definitive form (the “ Series A Warrants ”), each of which shall be exercisable for one Common Share, and (ii) 240,000 warrants in definitive form (the “ Series B Warrants ” and, together with the Series A Warrants, the “ Warrants ”), each of which shall be exercisable for one Common Share. The exercise price per Warrant shall be $36.99 (the “ Exercise Price ”), subject to adjustment as described in Section 6.01 below.

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ARTICLE III

EXECUTION AND REGISTRATION OF WARRANTS

3.01 Execution of Warrant Certificates . Certificates substantially in the form of Exhibit A hereto (the “ Warrant Certificates ”) evidencing Warrants to be delivered pursuant to this Agreement shall be signed on behalf of Under Armour by its chairman of the board or its president or a vice president and by its secretary or an assistant secretary.

Any Warrant Certificate may be signed on behalf of Under Armour by any person who, at the actual date of the execution of such Warrant Certificate, shall be a proper officer of Under Armour to sign such Warrant Certificate, although at the date of the execution of this Agreement any such person was not such officer.

3.02 Registration . Upon issuance of the Warrants, Under Armour shall number and register the Warrant Certificates in a register that shall be maintained by Under Armour. Prior to due presentment for registration of transfer of any Warrant, Under Armour may deem and treat the registered holder of each Warrant Certificate as the absolute owner thereof (notwithstanding any notation of ownership or other writing thereon made by anyone) for all purposes and shall not be affected by any notice to the contrary. The Warrants shall initially be registered in the name of NFL Properties.

3.03 Registration of Transfers and Exchanges .

(a) General Restrictions on Transfer . The Warrants may not be Disposed of by any holder thereof without the prior written consent of Under Armor for a period, commencing on the Warrant Issue Date, of (i) one year with respect to the Series A Warrants and (ii) three years with respect to the Series B Warrants; provided , however , that NFL Properties or any permitted transferee of NFL Properties may (A) pledge, hypothecate or otherwise similarly transfer the Warrants solely (1) in order to comply with the requirements of any league-level institutional lending facility and (2) following the expiration or termination of the Promotional Rights Agreement or any replacement agreement and any extension thereof, in connection with any bona fide hedging or other similar brokers’ transaction and (B) otherwise transfer the Warrants to any National Football League member club or its respective controlling owner (or any holding companies or other wholly-owned affiliates controlled by or under common control with such persons); and provided further that any such transferees (other than the collateral agent or other pledgee in respect of an institutional lending facility, solely for purposes of the pledge of the Warrants (but not any subsequent foreclosure or other transfer in execution upon such pledge)) shall agree in writing prior to such transfer to be bound by all of the terms of this Agreement, including the restrictions on transfers. The restrictions on transfer contemplated in this Section 3.03 shall terminate immediately prior to a Change of Control and shall not be applicable to the Underlying Shares following an exercise of the Warrant by the Warrant holder.

(b) Transfer and Exchange of Warrants . When Warrant Certificates are presented to Under Armour with a request to register the transfer of Warrants under circumstances permitted by the terms of this Agreement, Under Armour shall register the transfer or make the exchange as requested if the requirements under this Agreement as set forth in this Section 3.03 for such transactions are met; provided , however , that the Warrant Certificates presented or surrendered for registration of transfer or exchange shall be duly endorsed and shall be accompanied by a duly completed and signed Certificate to be

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Delivered upon Exchange or Registration of Transfer of Warrants in substantially the form of Exhibit B hereto.

(c) Legends .

(i) Except to the extent permitted by the following paragraph (ii), each Warrant Certificate (and all Warrant Certificates issued in exchange therefor or substitution thereof) shall bear legends substantially to the following effect:

THE TRANSFER OF THE SECURITIES EVIDENCED HEREBY IS SUBJECT TO RESTRICTIONS ON TRANSFERABILITY PURSUANT TO THE WARRANT AGREEMENT DATED AS OF AUGUST 3, 2006.

THE SECURITY (OR ITS PREDECESSOR) EVIDENCED HEREBY WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER SECTION 5 OF THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, AND THE SECURITY EVIDENCED HEREBY MAY NOT BE OFFERED, PLEDGED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.

(ii) Upon any sale or transfer of a Warrant permitted by Section 3.03(a) and pursuant to Rule 144 under the Securities Act or an effective registration statement under the Securities Act, Under Armour shall permit the holder thereof to exchange such Warrant for a warrant in definitive form that does not bear the legend set forth in the second paragraph of Section 3.03(b)(i) above and rescind any related restriction on the transfer of such Warrant.

(d) Obligations with Respect to Transfers and Exchanges of Warrants .

(i) To permit registrations of transfers and exchanges made in accordance with the terms of this Agreement, Under Armour shall execute new Warrant Certificates.

(ii) All Warrant Certificates issued upon any registration, transfer or exchange of Warrant Certificates made in accordance with the terms of this Agreement shall be the valid obligations of Under Armour, entitled to the same benefits under this Warrant Agreement as the Warrants surrendered upon the registration of transfer or exchange.

ARTICLE IV

EXERCISE OF WARRANTS

4.01 Terms of Warrants: Exercise of Warrants . Upon the terms and subject to the conditions of this Agreement, each Warrant holder shall have the right, which may be exercised commencing (i) with respect to the Series A Warrants, on the first anniversary (the “ Series A Exercise Date ”) of the date of issuance of the Warrants (the “ Warrant Issue Date ”) and (ii) with respect to the Series B Warrants, on the third anniversary (the “ Series B Exercise Date ”) of the Warrant Issue Date, and terminating in the case of each of (i) and (ii) at 5:00 p.m., New York City time, on the Expiration Date to receive from Under Armour the number of fully paid and nonassessable Underlying Shares that the holder may at the time be

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entitled to receive on exercise of such Warrants upon payment of the Exercise Price then in effect for such Underlying Shares. Notwithstanding anything in this Agreement to the contrary, all of the Warrants shall become exercisable immediately prior to any Change of Control.

A Warrant may be exercised upon surrender to Under Armour at any office or agency maintained for that purpose by Under Armour (each, a “ Warrant Office ”) of the Warrant Certificates to be exercised with the form of election to purchase on the reverse thereof duly completed and signed, which signature, if the holder of such Warrant is not NFL Properties, shall be guaranteed by a bank or trust company having an office or correspondent in the United States or a broker or dealer which is a member of a registered securities exchange or the NASD, Inc., and upon payment to Under Armour of the Exercise Price as adjusted as herein provided for each of the Underlying Shares in respect of which such Warrants are then exercised. Payment of the aggregate Exercise Price shall be made in cash by Federal wire transfer in immediately available funds to the account designated by Under Armour or by certified or official bank check, payable to the order of Under Armour; provided , however , that a holder so exercising may, in lieu of payment of the Exercise Price in cash, elect to receive a number of Underlying Shares equal to (A) the number of Underlying Shares for which such holder’s Warrants are exercised minus (B) the number of Underlying Shares having an aggregate Fair Market Value at the time of exercise equal to the aggregate Exercise Price that would otherwise have been paid in respect of the Warrants by the Warrant holder (excluding any brokerage fees or other costs or commissions).

Subject to the provisions of Section 4.02, upon surrender of Warrants and payment of the Exercise Price as provided above by any holder, Under Armour shall issue to such holder as soon as practicable but in no event later than three business days thereafter a certificate or certificates for the appropriate number of Underlying Shares to which such holder is entitled, registered or otherwise placed in, or payable to the order of, such name or names as may be directed in writing by such holder, and shall deliver such certificate or certificates representing the Underlying Shares and any other securities or property (including any money) to such holder or any other Person or Persons entitled to receive the same, together with an amount in cash in lieu of any fraction of a share as provided in Section 7.02. Any such certificate or certificates representing the Underlying Shares shall be deemed to have been issued and any Person so designated to be named therein shall be deemed to have become a holder of record of such Underlying Shares as of the date of the surrender of such Warrants and payment of the Exercise Price.

The Warrants shall be exercisable, subject to the provisions of this Agreement, at the election of the holders thereof, either in full or from time to time in part, and, in the event that a certificate evidencing Warrants is exercised in respect of fewer than all of the Underlying Shares issuable on such exercise at any time prior to the Expiration Date, a new Warrant Certificate evidencing the remaining Warrant or Warrants (which remaining Warrants will reflect the deduction of any Underlying Shares as a result of the payment of the Exercise Price on a net cashless basis as described in the proviso to the second paragraph of this Section 4.01) will be issued, and the duly executed Warrant Certificates will be delivered pursuant to the provisions of this Section 4.01.

All Warrant Certificates surrendered upon exercise of Warrants shall be canceled by Under Armour.

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Under Armour shall keep copies of this Agreement and any notices given or received hereunder available for inspection by the holders during normal business hours at any Warrant Office.

4.02 Payment of Taxes . Under Armour will pay all documentary stamp taxes attributable to the issuance of Underlying Shares upon the exercise of Warrants; provided, however, that Under Armour shall not be required to pay any Tax or Taxes that may be payable in respect of any transfer involved in the issue of any Warrant Certificates or any certificates for Underlying Shares in a name other than that of the holder of a Warrant Certificate surrendered upon the exercise of a Warrant, and Under Armour shall not be required to issue or deliver such Warrant Certificates unless or until the Person or Persons requesting the issuance thereof shall have paid to Under Armour the amount of such Tax or shall have established to the reasonable satisfaction of Under Armour that such Tax has been paid.

ARTICLE V

MISSING OR MUTILATED WARRANT CERTIFICATES; RESERVATION AND

LISTING OF WARRANT SHARES

5.01 Mutilated or Missing Warrant Certificates . In case any of the Warrant Certificates shall be mutilated, lost, stolen or destroyed, Under Armour shall issue, in exchange and substitution for and upon cancellation of the mutilated Warrant Certificate, or in lieu of and substitution for the Warrant Certificate lost, stolen or destroyed, a new Warrant Certificate of like tenor and representing an equivalent number of Warrants, but only upon receipt of evidence reasonably satisfactory to Under Armour of such loss, theft or destruction of such Warrant Certificate and indemnity, if requested, also reasonably satisfactory to it.

5.02 Reservation of Underlying Shares . Under Armour will at all times reserve and keep available, free from preemptive rights, out of the aggregate of its authorized but unissued Common Shares or its authorized and issued Common Shares held in its treasury, for the purpose of enabling it to satisfy any obligation to issue Underlying Shares upon exercise of Warrants, the maximum number of Common Shares which may then be deliverable upon the exercise of all outstanding Warrants.

If there is a transfer agent for the Common Shares (the “ Transfer Agent ”), such Transfer Agent and every subsequent transfer agent for any shares of Under Armour’s capital stock issuable upon the exercise of any of the rights of purchase aforesaid will be irrevocably authorized and directed at all times to reserve such number of authorized shares as shall be required for such purpose. Under Armour will keep a copy of this Agreement on file with the Transfer Agent and with every subsequent transfer agent for any shares of Under Armour’ capital stock issuable upon the exercise of the rights of purchase represented by the Warrants. Under Armour will supply such Transfer Agent with duly executed certificates for such purposes and will provide or otherwise make available any cash which may be payable as provided in Section 7.02. Under Armour will furnish such Transfer Agent a copy of all notices of adjustments and certificates related thereto, transmitted to each holder of the Warrants pursuant to Section 12.05.

Under Armour covenants that all Underlying Shares which may be issued upon exercise of Warrants in accordance with the terms of this Agreement (including the payment of the Exercise Price) will, upon issue, be duly authorized, validly issued, fully paid, nonassessable, free of preemptive rights and free from all Taxes, liens, charges and security interests with respect to the issue thereof.

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ARTICLE VI

ADJUSTMENT OF NUMBER OF UNDERLYING SHARES ISSUABLE

6.01 Adjustment . The number and kind of shares purchasable upon the exercise of Warrants and the Exercise Price shall be subject to adjustment from time to time after the date of issuance of the Warrants as follows:

(a) Stock Splits, Combinations, etc. If Under Armour shall (A) pay a dividend or make a distribution on its Common Shares in shares of its capital stock (whether Common Shares or capital stock of any other class), (B) subdivide its outstanding Common Shares into a greater number of shares, (C) combine its outstanding Common Shares into a smaller number of shares or (D) issue by reclassification, recapitalization or reorganization of its outstanding Common Shares any shares of its capital stock, the Exercise Price in effect and the number of Underlying Shares issuable upon exercise of each Warrant immediately prior to such action shall be adjusted so that the holder of any Warrant thereafter exercised shall be entitled to receive the number of Underlying Shares that such holder would have owned immediately following such action had such Warrant been exercised immediately prior thereto. An adjustment made pursuant to this Section 6.01(a) shall become effective immediately after the record date in the case of a dividend and shall become effective immediately after the effective date in the case of a subdivision, combination or reclassification. If, as a result of an adjustment made pursuant to this Section 6.01(a), the holder of any Warrant thereafter exercised shall become entitled to receive shares of two or more classes of capital stock of Under Armour, the board of directors of Under Armour shall in good faith determine the allocation of the adjusted Exercise Price between or among shares of such classes of capital stock.

(b) Reclassification, Combinations, Mergers, etc. In case of any reclassification or change of outstanding Common Shares issuable upon exercise of the Warrants (other than as set forth in Section 6.01(a) and other than a change in par value, or from par value to no par value, or from no par value to par value or as a result of a subdivision or combination), or in case of any consolidation or merger of Under Armour with or into another corporation (other than a merger or acquisition in which Under Armour is the continuing corporation and which does not result in any reclassification or change of the then outstanding Common Shares or other capital stock issuable upon exercise of the Warrants) or in case of any sale, lease or conveyance to another corporation of the property of Under Armour as an entirety or substantially as an entirety or recapitalization or reorganization, then, as a condition of such reclassification, change, consolidation, merger, sale, lease, conveyance, recapitalization or reorganization, Under Armour shall, or shall cause such a successor or purchasing corporation, as the case may be, at or prior to such reclassification, change, consolidation, merger, sale, lease, conveyance, recapitalization or reorganization, make lawful and adequate provision whereby the holders of Warrants then outstanding shall have the right thereafter to receive on exercise of such Warrant the kind and amount of shares of stock or other securities or property receivable upon such reclassification, change, consolidation, merger, sale, lease, conveyance, recapitalization or reorganization equivalent in value to the number of Common Shares issuable upon exercise of such Warrant immediately prior to such reclassification, change, consolidation, merger, sale, lease, conveyance, recapitalization or reorganization and enter into a supplemental warrant agreement so providing. Such provisions shall include provision for adjustments as nearly

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equivalent to the adjustments provided for in this Section 6.01. The above provisions of this Section 6.01(b) shall similarly apply to successive reclassifications and changes of Common Shares and to successive consolidations, mergers, sales, leases, conveyances, recapitalizations or reorganizations.

(c) Dividends and Distributions . If Under Armour shall, at any time or from time to time after the date hereof, distribute to all the holders of Common Shares any dividend or other distribution of cash, evidences of its indebtedness, other securities or other properties or assets (in each case other than dividends payable in Common Shares, any rights to subscribe for or to purchase, or any warrants or options for the purchase of, Common Shares or any stock or securities convertible into or exchangeable for Common Shares (any such rights, warrants or options being herein called “ Exercisable Securities ” and any such convertible or exchangeable stock or securities being herein called “ Convertible Securities ”)) or any options, warrants or other rights to subscribe for or purchase any of the foregoing, then (A) the Exercise Price shall be decreased to a price determined by multiplying the Exercise Price then in effect by a fraction, the numerator of which shall be the Fair Market Value per share of Common Shares on the record date for such distribution less the sum of (X) the cash portion, if any, of such distribution per share of Common Shares outstanding (exclusive of any treasury shares) on the record date for such distribution plus (Y) the then current Fair Market Value per share of Common Shares outstanding (exclusive of any treasury shares) on the record date for such distribution of that portion, if any, of such distribution consisting of evidences of indebtedness, other securities, properties, assets, options, warrants or subscription or purchase rights, and the denominator of which shall be such Fair Market Value per Common Share and (B) the number of Underlying Shares issuable upon the exercise of each Warrant shall be increased to a number determined by multiplying the number of Underlying Shares so issuable immediately prior to the record date for such distribution by a fraction, the numerator of which shall be the Exercise Price in effect immediately prior to the adjustment required by clause (A) of this sentence and the denominator of which shall be the Exercise Price in effect immediately after such adjustment. The adjustments required by this Section 6.01(c) shall be made whenever any such distribution occurs retroactive to the record date for the determination of shareholders entitled to receive such distribution. No adjustment shall be made pursuant to this Section 6.01(c) that shall have the effect of decreasing the number of Underlying Shares issuable upon exercise of the Warrants or increasing the Exercise Price.

(d) Issuance of Common Stock Below Current Fair Market Value . If Under Armour shall, in a transaction to which Sections 6.01(a) through (c) are inapplicable, issue or sell Common Shares, or rights, options, warrants or convertible or exchangeable securities containing the right to subscribe for or purchase Common Shares, at a price per Common Share (determined, in the case of such rights, options, warrants or convertible or exchangeable securities, by dividing (A) the total amount receivable by Under Armour in consideration of the issuance and sale of such rights, options, warrants or convertible or exchangeable securities, plus the total consideration, if any, payable to Under Armour upon exercise, conversion or exchange thereof, by (B) the total number of Common Shares covered by such rights, options, warrants or convertible or exchangeable securities) that is lower than the then current Fair Market Value per Common Share in effect immediately prior to such sale or issuance, then the number of Underlying Shares thereafter issuable upon the exercise of all Warrants then outstanding shall be determined by adding the number of Underlying Shares theretofore issuable upon exercise of all Warrants then outstanding to the product of (x) the Cheap Stock Issued, multiplied by (y) the Ownership Ratio. Such adjustment shall be made successively whenever any such sale or issuance is made.

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For purposes of this Section 6.01(d), (i) the “ Cheap Stock Issued ” shall be the number of additional Common Shares issued or offered by Under Armour for subscription or purchase as described above minus the number of Common Shares that the aggregate offering price of the total number of Common Shares so offered would purchase at the then current Fair Market Value per Common Share and (ii) the “ Ownership Ratio ” shall be a fraction, the numerator of which shall be the number of Underlying Shares prior to such time issuable upon exercise of all Warrants then outstanding, and the denominator of which shall be the number of Common Shares then outstanding (on a fully diluted basis) on the date of issuance or sale of such Common Shares or such rights, options, warrants or convertible or exchangeable securities. For purposes of such adjustments, the Common Shares which the holder of any such rights, options, warrants or convertible or exchangeable securities shall be entitled to subscribe for or purchase shall be deemed to be issued and outstanding as of the date of the sale and issuance of the rights, warrants or convertible or exchangeable securities.

Any adjustment to the number of Underlying Shares issuable upon exercise of all Warrants then outstanding made pursuant to this Section 6.01(d) shall be allocated among each Warrant then outstanding on a pro rata basis.

(e) Consideration Received . If any Common Shares, Exercisable Securities or Convertible Securities shall be issued, sold or distributed for a consideration other than cash, the amount of the consideration other than cash received by Under Armour in respect thereof shall be deemed to be the then current Fair Market Value of such consideration. If any options shall be issued in connection with the issuance and sale of other securities of Under Armour, together comprising one integral transaction in which no specific consideration is allocated to such options by the parties thereto, such options shall be deemed to have been issued without consideration; provided, however, that if such options have an exercise price equal to or greater than the Fair Market Value of the Common Shares on the date of issuance of such options, then such options shall be deemed to have been issued for consideration equal to such exercise price.

(f) Deferral of Certain Adjustments . No adjustment to the Exercise Price (including the related adjustment to the number of Underlying Shares issuable upon the exercise of each Warrant) shall be required hereunder unless such adjustment, together with other adjustments carried forward as provided below, would result in an increase or decrease of at least one percent of the Exercise Price; provided that any adjustments which by reason of this Section 6.01(f) are not required to be made shall be carried forward and taken into account in any subsequent adjustment. No adjustment need be made for a change in the par value of the Common Shares. All calculations under this Section 6.01 shall be made to the nearest 1/1,000 of one cent or to the nearest 1/1,000 of a share, as the case may be.

(g) Other Adjustments .

(i) In the event that at any time, as a result of an adjustment made pursuant to this Section 6.01, the holders of Warrants shall become entitled to receive any securities of Under Armour other than Common Shares, thereafter the number of such other securities so receivable upon exercise of the Warrants and the Exercise Price applicable to such exercise shall be subject to adjustment from time to time in a manner and on terms as nearly equivalent as practicable to the provisions with respect to the Common Shares contained in this Section 6.01, mutatis mutandis .

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(ii) In case any event shall occur as to which the provisions of this Section 6.01 are not strictly applicable but the failure to make any adjustment would not fairly protect the rights represented by the Warrants in accordance with the essential intent and principles of this Section 6.01, then in each such case, Under Armour shall make a good faith adjustment to the Exercise Price and the number of Underlying Shares in accordance with the intent of this Section 6.01; provided, however, that no such adjustment shall have the effect of decreasing the number of Underlying Shares issuable upon exercise of this Warrant or increasing the Exercise Price.

(h) No Adjustment . Without limiting any other exception contained in this Section 6.01, and in addition thereto, no adjustment will be made for:

(i) exercises or conversions of any Exercisable Securities or Convertible Securities outstanding on the date hereof (to the extent such exercise or conversion is made in accordance with the terms of such Exercisable Security or Convertible Security as in effect on the date hereof);

(ii) issuances of Exercisable Securities, Convertible Securities or Common Shares to directors, employees, consultants or suppliers of Under Armour or any of its subsidiaries pursuant to Under Armour’s current or future plans or the exercise or conversion of such Exercisable Securities or Convertible Securities; provided , however , that such issuances to such consultants or suppliers shall not exceed 3% of the Common Shares then outstanding during the period commencing on the Warrant Issue Date and ending on the Expiration Date;

(iii) issuances of rights to purchase Common Shares pursuant to a plan of Under Armour for reinvestment of dividends or interest;

(iv) except as set forth in Section 6.01(d), issuances of Exercisable Securities, Convertible Securities or Common Shares in bona fide public offerings or private placements pursuant to Section 4(2) of the Securities Act, Regulation D thereunder or Regulation S, involving at least one investment bank of international reputation, provided , however , that any Exercisable Securities, Convertible Securities or Common Shares issued pursuant to such private placement shall not be issued for consideration per share less than Fair Market Value at the time of issuance; or

(v) except as set forth in Section 6.01(d), issuances of Exercisable Securities, Convertible Securities or Common Shares in connection with the establishment of commercial bank facilities, capital lease obligations or other issuances of primarily debt obligations or securities; provided , however , that any Exercisable Securities, Convertible Securities or Common Shares issued in connection with such commercial bank facilities, capital lease obligations or other issuances of primarily debt obligations or securities shall not be issued for consideration per share less than Fair Market Value at the time of issuance.

6.02 Notice of Adjustment . Upon the occurrence of each adjustment pursuant to Section 6.01, Under Armour shall promptly provide to the Warrant holder a written notice of

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such event and the computation of the adjustment in accordance with the terms hereof. Under Armour shall provide the Warrant holder with a certificate from an officer of Under Armour briefly stating the facts requiring the adjustment and the manner of computing such adjustment.

ARTICLE VII

STATEMENTS ON WARRANTS

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

7.02 Fractional Interest . Under Armour shall not be required to issue fractional Common Shares on the exercise of Warrants. If more than one Warrant shall be presented for exercise in full at the same time by the same holder, the number of full Common Shares which shall be issuable upon such exercise shall be computed on the basis of the aggregate number of Common Shares acquirable on exercise of the Warrants so presented. If any fraction of a Common Share would, except for the provisions of this Section 7.02, be issuable on the exercise of any Warrant (or specified portion thereof), Under Armour shall pay, or direct the Transfer Agent, if any, to pay, an amount in cash determined by it to equal the Fair Market Value per Common Share multiplied by such fraction computed to the nearest whole cent. The holders, by their acceptance of the Warrant Certificates, expressly waive any and all rights to receive any fraction of a share of Common Shares or a stock certificate representing a fraction of a share of Common Shares.

7.03 Notices to Warrant Holders .

In the event that Under Armour:

(i) authorizes the issuance to all holders of Common Shares of rights, options or warrants to subscribe for or purchase Common Shares or of any other subscription rights or warrants;

(ii) authorizes the distribution to all holders of Common Shares of evidence of its indebtedness or assets;

(iii) proposes to become a party to any consolidation or merger for which approval of any shareholders of Under Armour is required, or of the conveyance or transfer of the properties and assets of Under Armour substantially as an entirety, or of any reclassification or change of Common Shares issuable upon exercise of the Warrants (other than a change in par value, or from par value to no par value, or from no par value to par value, or as a result of a subdivision or combination), or a tender offer or exchange offer for Common Shares; or

(iv) commences a voluntary or involuntary dissolution, liquidation or winding up,

then Under Armour shall cause to be given to each of the registered holders of the Warrants at such holder’s address appearing on the Warrant register, at least 10 days prior to the applicable record date hereinafter specified, or promptly in the case of events for which there

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is no record date, by first class mail, postage prepaid, a written notice stating (i) the date as of which the holders of record of Common Shares to be entitled to receive any such rights, options, warrants or distribution are to be determined, (ii) the initial expiration date set forth in any tender offer or exchange offer for Common Shares or (iii) the date on which any such consolidation, merger, conveyance, transfer, dissolution, liquidation or winding up is expected to become effective or consummated, and, if applicable, the date as of which it is expected that holders of record of Common Shares shall be entitled to exchange such shares for securities or other property, if any, deliverable upon such reclassification, consolidation, merger, conveyance, transfer, dissolution, liquidation or winding up. The failure to give the notice required by this Section 7.03 or any defect therein shall not affect the legality or validity of any distribution, right, option, warrant, consolidation, merger, conveyance, transfer, dissolution, liquidation or winding up, or the vote upon any action. Nothing contained in this Agreement or in any of the Warrant Certificates shall be construed as conferring upon the holders thereof the right to vote or to consent or to receive notice as shareholders in respect of the meetings of shareholders or the election of directors of Under Armour or any other matter, or any rights whatsoever as shareholders of Under Armour.

ARTICLE VIII

CONDITIONS

8.01 Conditions to Obligations of the Parties . The obligations of each of NFL Properties and Under Armour to consummate the grant of the Warrants are subject to the satisfaction of each of the following conditions:

(a) Promotional Rights Agreement Execution . The execution and delivery of the Promotional Rights Agreement shall have occurred.

(b) Compliance with Laws; No Adverse Action or Decision . No Governmental Authority shall have enacted, issued, promulgated, enforced or entered any Law or preliminary or permanent injunction that remains in effect and that restrains, enjoins, materially delays, prohibits or otherwise makes illegal, or have commenced any proceeding that seeks to restrain, enjoin, materially delay, prohibit or otherwise make illegal, the consummation of the transactions contemplated herein.

ARTICLE IX

CLOSING FOR THE WARRANTS

9.01 Closing . At Closing, Under Armour shall deliver to NFL Properties Warrant Certificates evidencing the Warrants to be issued to it hereunder.

ARTICLE X

REPRESENTATIONS AND WARRANTIES OF NFL PROPERTIES

NFL Properties represents and warrants to Under Armour as follows:

10.01 Corporate Existence of NFL Properties . NFL Properties is a limited liability company duly organized and validly existing under the laws of the State of Delaware.

10.02 Authorization; Enforceability of this Agreement . The execution, delivery and performance of this Agreement by NFL Properties and the consummation by NFL Properties of the transactions contemplated hereby are within the company power and authority of NFL Properties and have been duly and validly authorized by all necessary company action on the part of NFL Properties. This Agreement has been duly executed and delivered by, and is the legal, valid, binding and enforceable obligation of, NFL Properties.

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10.03 Accredited Investor . (i) NFL Properties is an “accredited investor,” as such term is defined in Rule 501(a) of the Securities Act and (ii) each owner of NFL Properties is an “accredited investor.”

ARTICLE XI

REPRESENTATIONS AND WARRANTIES OF UNDER ARMOUR

Under Armour represents and warrants to NFL Properties as follows:

11.01 Corporate Existence and Power of Under Armour . Under Armour is a corporation duly organized and validly existing under the laws of the State of Maryland and has all requisite corporate power and authority to own, license, use or lease and operate its assets and properties and to carry on its business as it is now conducted and where currently conducted.

11.02 Authorization; Enforceability of this Agreement . The execution, delivery and performance of this Agreement by Under Armour and the consummation by Under Armour of the transactions contemplated hereby are within the corporate power and authority of Under Armour and have been duly and validly authorized by all necessary corporate action on the part of Under Armour. This Agreement has been duly executed and delivered by, and is the legal, valid, binding and enforceable obligation of, Under Armour.

ARTICLE XII

MISCELLANEOUS

12.01 Fees and Expenses . Whether or not the Closing occurs, each Party to this Agreement shall bear its own fees and expenses incurred by such Party and the transactions contemplated thereby.

12.02 Survival of Representations and Warranties . Notwithstanding any investigation conducted or notice or knowledge obtained by or on behalf of any Party, each representation or warranty in this Agreement or in certificates delivered pursuant to this Agreement shall survive the Closing.

12.03 Entire Agreement . This Agreement and the documents described herein or attached or delivered pursuant hereto set forth the entire agreement between the Parties with respect to the transactions contemplated by this Agreement and supersedes all prior agreements and understandings relating thereto.

12.04 Waivers and Amendments . No amendment of, or variation of, this Agreement shall be effective unless made between the Parties and in writing. No waiver shall be effective hereunder unless contained in a writing signed by the Party sought to be charged with such waiver. No failure on the part of any Party to exercise or delay in exercising any right hereunder shall be deemed a waiver thereof, nor shall any single or partial exercise preclude any further or other exercise of such or any other right.

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12.05 Notices . All notices delivered hereunder shall be in writing in accordance with this Section 12.05 and shall be communicated to the following addresses:

If to NFL Properties:

NFL Properties LLC

280 Park Avenue

New York, NY 10017

Tel: 212-450-2537

Facsimile: 212-681-7598

Attention: Gary Gertzog

With a copy to:

Covington & Burling LLP

1201 Pennsylvania Avenue, N.W.

Washington, D.C. 20004

Tel: 202-662-5400

Facsimile: 202-778-5400

Attention: Bruce Wilson

If to Under Armour:

Under Armour, Inc.

1020 Hull Street

3rd Floor

Baltimore, MD 21230

Tel: 410-454-6428

Facsimile: 410-234-9832

Attention: Kevin M. Haley

With a copy to:

Cleary Gottlieb Steen & Hamilton LLP

One Liberty Plaza

New York, NY 10006

Tel: 212-225-2000

Facsimile: 212-225-3999

Attention: Stephen H. Shalen

Any such notice shall be served by sending it by facsimile transmission or by certified air mail (postage prepaid, return receipt requested, if available). Any notice shall be deemed to have been served on receipt of confirmation of successful transmission or delivery.

12.06 Counterparts . This Agreement may be executed by the Parties in counterparts.

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12.07 Governing Law and Submission to Jurisdiction .

(a) This Agreement and, to the fullest extent permitted by law, all matters arising out of or relating in any way to this Agreement, shall be governed by the law of the State of New York.

(b) To the fullest extent permitted by applicable law, each party hereto (i) agrees that any claim, action or proceeding by such party seeking any relief whatsoever arising out of, or in connection with, this Agreement or the transactions contemplated hereby shall be brought only in the United States District Court for the Southern District of New York and in any New York State court located in the Borough of Manhattan and not in any other State or Federal court in the United States of America or any court in any other country, (ii) agrees to submit to the exclusive jurisdiction of such courts located in the State of New York for purposes of all legal proceedings arising out of, or in connection with, this Agreement or the transactions contemplated hereby and (iii) irrevocably waives any objection which it may now or hereafter have to the laying of the venue of any such proceeding brought in such a court and any claim that any such proceeding brought in such a court has been brought in an inconvenient forum.

12.08 Benefits of this Agreement . Prior to the exercise of the Warrants, no holder of a Warrant Certificate, as such, shall be entitled to any rights of a shareholder of Under Armour, including, without limitation, the right to receive dividends or subscription rights, the right to vote, to consent, to exercise any preemptive right, to receive any notice of meetings of shareholders for the election of directors of Under Armour or any other matter or to receive any notice of any proceedings of Under Armour, except as may be specifically provided for herein. The holders of the Warrants are not entitled to share in the assets of Under Armour in the event of the liquidation, dissolution or winding up of Under Armour’s affairs.

12.09 Successors and Assigns . Except as otherwise expressly provided herein, the provisions of this Agreement shall inure to the benefit of, and be binding upon, each Party and its successors and permitted assigns. None of this Agreement, the Warrants, the Warrant Certificates, nor any rights hereunder or thereunder, shall be assignable by either Party (except, in respect of such an assignment by Under Armour, in the case of a merger or consolidation of Under Armour in which Under Armour is not the surviving entity and the surviving entity assumes the obligations of Under Armour hereunder) without the prior written consent of the non-assigning Party.

12.10 Warrant Agent . Under Armour may appoint a warrant agent to perform the administrative tasks hereunder that are customarily performed by an agent.

12.11 No Impairment . Under Armour will not, by amendment of its Articles of Incorporation or bylaws, or through reorganization, consolidation, merger, dissolution, issue or sale of securities, sale of assets or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Agreement or of any Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the Warrant holder against impairment. Without limiting the generality of the foregoing, Under Armour (a) shall not increase the par value of any Common Shares upon the exercise of this Warrant above the Exercise Price, (b) shall take all such action as may be necessary or appropriate in order that Under Armour may validly and legally issue fully paid and nonassessable Common

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Shares upon the exercise of any Warrant and (c) shall use its best efforts to obtain all such authorizations, exemptions or consents from any Governmental Authority having jurisdiction thereof as may be necessary to enable Under Armour to perform its obligations under this Agreement and any Warrant.

12.12 Exchange Act Reports . With a view to making available to the Warrant holder the benefits of Rule 144 promulgated under the Securities Act or any other similar rule or regulation of the Securities and Exchange Commission (the “ SEC ”) that may at any time permit the Warrant holder to sell securities of the Company to the public without registration (“ Rule 144 ”), Under Armour agrees to

(a) make and keep public information available, as those terms are understood and defined in Rule 144, at all times;

(b) file with the SEC in a timely manner all reports and other documents required of the Company under the Securities Act and the Exchange Act; and

(c) furnish to the Warrant holder so long as it owns Warrants, promptly upon request, (i) a written statement by Under Armour that it has complied with the reporting requirements of Rule 144, the Securities Act and the Exchange Act, (ii) a copy of the most recent annual or quarterly report of Under Armour and such other reports and documents so filed by Under Armour, and (iii) such other information as may be reasonably requested to permit the Warrant holder to sell such securities without registration.

[The remainder of this page intentionally left blank]

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IN WITNESS of the agreement set out above, each of the Parties has executed this Agreement by its duly authorized signatory on the date first written above.

Schedule 1.01

DEFINITIONS

“ Agreement ” has the meaning assigned to it in the Preamble.

“ Change of Control ” means any of the following events:

Notwithstanding the foregoing provisions of this definition, a “Change of Control” will not be deemed to have occurred solely because of the acquisition of securities of Under Armour (or any reporting requirement under the Exchange Act relating thereto) by an employment benefit plan maintained by Under Armour for its employees.

“ Cheap Stock Issued ” has the meaning assigned to it in Section 6.01(d).

“ Closing ” means completion of the issuance and delivery of the Warrants to NFL Properties.

“ Common Shares ” has the meaning assigned to it in the Recitals.

“ Convertible Securities ” has the meaning assigned to it in Section 6.01(c).

“ Dispose of ” or “ Disposal ” includes (i) offering, selling, pledging, mortgaging, contracting to sell, granting or agreeing to grant any option, right or warrant to purchase, lending, or otherwise howsoever transferring or disposing of, directly or indirectly, any legal or beneficial interest in Common Shares or any securities convertible into or exercisable or exchangeable for, or that represent the right to receive, Common Shares, or (ii) entering into any swap or other arrangement that transfers to another, in whole or in part, any economic consequences or beneficial ownership of Common Shares, whether any such transaction described in (i) or (ii) above is to be settled by delivery of Common Shares or other securities, in cash or otherwise.

Schedule 1.01-1

“ Exchange Act ” means the Securities Exchange Act of 1934, as amended.

“ Exercisable Securities ” has the meaning assigned to it in Section 6.01(c).

“ Exercise Price ” has the meaning assigned to it in Section 2.01.

“ Expiration Date ” means the 12 ^th anniversary of the Warrant Issue Date.

“ Fair Market Value ” means, (1) if the Common Shares are not registered under the Exchange Act, the price that would be paid for each Common Share in a sale of the equity capital of Under Armour on an on-going concern basis in an arms-length transaction between a willing buyer and a willing seller and assuming full disclosure of and understanding of all relevant information and reasonable period of time for effectuating a sale, which price shall be determined in good faith by the board of directors of Under Armour and (2) if the Common Shares are registered under the Exchange Act, (a) the average of the daily closing sales prices of the Common Shares for the 20 consecutive trading days immediately preceding such date, or (b) if the Common Shares have been registered under the Exchange Act for less than 20 consecutive trading days before such date, then the average of the daily closing sales prices for all of the trading days before such date for which closing sales prices are available, in the case of each of (2)(a) and (2)(b), as certified to the Warrant holder by the President, any Vice President or the Chief Financial Officer of Under Armour. The closing sales price for each such trading day shall be: (A) in the case of Common Shares listed or admitted to trading on any United States national securities exchange or quotation system, the closing sales price, regular way, on such day, or if no sale takes place on such day, the average of the closing bid and asked prices on such day; (B) in the case of Common Shares not then listed or admitted to trading on any national securities exchange or quotation system, the last reported sale price on such day, or if no sale takes place on such day, the average of the closing bid and asked prices on such day, as reported by a reputable quotation source designated by Under Armour; (C) in the case of Common Shares not then listed or admitted to trading on any national securities exchange or quotation system and as to which no such reported sale price or bid and asked prices are available, the average of the reported high bid and low asked prices on such day, as reported by a reputable quotation service, or a newspaper of general circulation in the Borough of Manhattan, City and State of New York, customarily published on each business day, designated by Under Armour, or if there shall be no bid and asked prices on such day, the average of the high bid and low asked prices, as so reported, on the most recent day (not more than 30 days prior to the date in question) for which prices have been so reported; and (D) if there are not bid and asked prices reported during the 30 days prior to the date in question, the Fair Market Value shall be determined as if the Common Shares were not registered under the Exchange Act.

“ Governmental Authority ” means any government or political subdivision or department thereof, any governmental, quasi-governmental or regulatory body, any commission, board, bureau, agency or instrumentality, any court or arbitrator or alternative dispute resolution body, or any association, corporation, or other entity controlled directly or indirectly by any government or political subdivision or department thereof, in each case whether national, provincial, local or foreign.

Schedule 1.01-2

“ Law ” means any law, treaty, statute, ordinance, code, rule, regulation, judgment, decree, order, writ, award, injunction or determination of any Governmental Authority.

“ NFL Properties ” has the meaning assigned to it in the Preamble.

“ Ownership Ratio ” has the meaning assigned to it in Section 6.01(d).

“ Party ” and “ Parties ” have the meanings assigned to them in the Preamble.

“ Person ” means any individual, corporation, company, association, partnership, limited liability company, joint venture, trust, unincorporated organization or Governmental Authority.

“ Promotional Rights Agreement ” has the meaning assigned to it in the Recitals.

“ Securities Act ” means the United States Securities Act of 1933, as amended from time to time.

“ Series A Exercise Date ” has the meaning assigned to it in Section 4.01.

“ Series B Exercise Date ” has the meaning assigned to it in Section 4.01.

“ Series A Warrants ” has the meaning assigned to it in Section 2.01.

“ Series B Warrants ” has the meaning assigned to it in Section 2.01.

“ Tax ” or “ Taxes ” means all taxes, including any interest, liabilities, fines, penalties or additions to tax that may become payable in respect thereof, imposed by any Governmental Authority, which taxes shall include, without limiting the generality of the foregoing, income taxes, payroll and employee withholding taxes, unemployment insurance, social security, sales and use taxes, excise taxes, franchise taxes, gross or net receipts taxes, occupation taxes, real and personal property taxes, ad valorem taxes, stamp taxes or duties, transfer taxes, capital taxes or duties, import duties, profits taxes, provisional profits taxes, salaries taxes, property taxes, estate duties, withholding taxes, workers’ compensation, and any other taxes, levies, duties, charges, imposts or withholdings or any other obligations of the same or of a similar nature whether arising before, on or after the date hereof.

“ Transfer Agent ” has the meaning assigned to it in Section 5.02.

“ Under Armour ” has the meaning assigned to it in the Preamble.

“ Underlying Shares ” means the Common Shares issued or issuable upon the exercise of the Warrants.

“ Warrant Issue Date ” has the meaning assigned to it in Section 4.01.

“ Warrants ” has the meaning assigned to it in Section 2.01.

“ Warrant Certificates ” has the meaning assigned to it in Section 3.01.

“ Warrant Office ” has the meaning assigned to it in Section 4.01.

Schedule 1.01-3

Exhibit A

[Form of Series A/B Warrant Certificate]

THE TRANSFER OF THE SECURITIES EVIDENCED HEREBY IS SUBJECT TO RESTRICTIONS ON TRANSFERABILITY PURSUANT TO THE WARRANT AGREEMENT DATED AS OF AUGUST 3, 2006.

THE SECURITY (OR ITS PREDECESSOR) EVIDENCED HEREBY WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER SECTION 5 OF THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND THE SECURITY EVIDENCED HEREBY MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.

This certificate (the “ Warrant Certificate ”) is issued pursuant to a warrant agreement, dated August 3, 2006, between Under Armour, Inc., a Maryland corporation (the “Company”), and NFL Properties LLC, a Delaware limited liability company, as amended from time to time (the “ Warrant Agreement ”). This Warrant Certificate certifies that                          , or its registered assigns, is the registered holder of an aggregate of                      Series [A][B] warrants (the “ Warrants ”) to purchase shares of Class A common stock, par value $0.0003  ¹ / 3  per share (the “ Common Shares ”), of the Company. Each Warrant entitles the holder to purchase from the Company, commencing [ for Series A Warrants, include : on the first anniversary of the date of issuance of the Warrants][ for Series B Warrants, include : on the third anniversary of the date of issuance of the Warrants], and terminating at 5:00 p.m., New York City time, on the Expiration Date, 1.00 Common Shares (such number of Common Shares subject to adjustment as described below) at an exercise price per Warrant of $36.99 (the “ Exercise Price ”), upon surrender of this Warrant Certificate and payment of the Exercise Price at any office or agency maintained for that purpose by the Company (each, a “ Warrant Office ”), subject to the conditions set forth herein and in the Warrant Agreement. No Warrant may be exercised after 5:00 p.m., New York City time, on the Expiration Date, and to the extent not exercised by such time such Warrants shall become void.

The Warrants evidenced by this Warrant Certificate are part of a duly authorized issue of Warrants and are issued pursuant to the Warrant Agreement, duly executed and delivered by the Company for the benefit of the holders (the words “ holders ” or “ holder ” meaning the registered holders or registered holder), from time to time, of the Warrants, which Warrant Agreement is hereby incorporated by reference in and made a part of this instrument and is hereby referred to for a description of the rights, limitation of rights, obligations, duties and immunities thereunder of the Company and the holders of the Warrants. A copy of the Warrant Agreement may be obtained by the holder hereof upon written request to the Company. Capitalized terms used herein without definition shall have the meanings ascribed to them in the Warrant Agreement.

Exhibit A-1

The holder of Warrants evidenced by this Warrant Certificate may exercise them by surrendering this Warrant Certificate, with the form of election to purchase set forth hereon properly completed and executed, together with payment of the Exercise Price in lawful money of the United States of America at any Warrant Office or on a net settlement basis. In the event that upon any exercise of Warrants evidenced hereby the number of Warrants exercised shall be less than the total number of Warrants evidenced hereby, there shall be issued to the holder hereof or his assignee a new Warrant Certificate evidencing the number of Warrants not exercised. No adjustment shall be made for any dividends on any Common Shares issuable upon exercise of this Warrant.

The Warrant Agreement provides that upon the occurrence of certain events the number of Common Shares issuable upon the exercise of each Warrant shall, subject to certain conditions, be adjusted. No fractions of a Common Share will be issued upon the exercise of any Warrant, but the Company will pay in cash the Fair Market Value of any fraction of a Common Share that would otherwise be issuable upon the exercise of any Warrant.

Warrant Certificates, when surrendered at any Warrant Office by the registered holder thereof in person or by legal representative or attorney duly authorized in writing, may be exchanged for a new Warrant Certificate or new Warrant Certificates evidencing in the aggregate a like number of Warrants, in the manner and subject to the limitations provided in the Warrant Agreement, without charge except for any Tax or other governmental charge imposed in connection therewith.

Upon due presentment for registration of transfer of this Warrant Certificate at any Warrant Office, a new Warrant Certificate evidencing in the aggregate a like number of Warrants shall be issued to the transferee in exchange for this Warrant Certificate, subject to the limitations provided in the Warrant Agreement, without charge except for any Tax or other governmental charge imposed in connection therewith.

The Company may deem and treat the registered holder hereof as the absolute owner of this Warrant Certificate (notwithstanding any notation of ownership or other writing hereon made by anyone) for the purpose of any exercise hereof and for all other purposes, and the Company shall not be affected by any notice to the contrary.

The Common Shares issuable upon exercise of this Warrant shall constitute Registrable Securities (as such term is defined in that certain Registration Rights Agreement, of even date herewith, by and between the Company and NFL Properties (the “ Registration Rights Agreement ”)). Each Holder (as defined in the Registration Rights Agreement) shall be entitled to all of the benefits afforded to a holder of any such Registrable Securities under the Registration Rights Agreement and each such Warrant holder, by its acceptance of the Warrant, agrees to be bound by and to comply with the terms and conditions of the Registration Rights Agreement applicable to such Warrant holder as a holder of such Registrable Securities. The Company shall use its reasonable best efforts to cause the Common Shares issuable upon the exercise of this Warrant, when issued, to be listed on each securities exchange or quotation system on which securities of the same class are listed or traded.

THIS WARRANT CERTIFICATE AND, TO THE FULLEST EXTENT PERMITTED BY LAW, ALL MATTERS ARISING OUT OF OR RELATING IN ANY WAY TO THIS WARRANT CERTIFICATE, SHALL BE GOVERNED BY THE LAW OF THE STATE OF NEW YORK.

Exhibit 4.2

REGISTRATION RIGHTS AGREEMENT

REGISTRATION RIGHTS AGREEMENT (this “ Agreement ”), dated as of August 3, 2006, by and among Under Armour Inc., a Maryland corporation (the “ Company ”), and NFL Properties LLC, a Delaware limited liability company (“ NFL Properties ” and, together with its permitted transferees pursuant to the Warrant Agreement (as defined below), the “ Holders ”).

RECITALS

A. In connection with the consummation of a proposed Promotional Rights Agreement (the “ Transaction ”) between the Company and NFL Properties, the Company has agreed to issue to NFL Properties certain warrants to purchase equity securities of the Company.

B. In order to induce NFL Properties to enter into the Transaction, the Company has agreed to grant certain securities registration rights to the Holders as set forth herein.

AGREEMENTS

In consideration of the premises and the mutual covenants herein contained and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows:

1. Definitions and General Interpretive Principles . The following capitalized terms shall have the following meanings when used in this Agreement:

“ Adverse Disclosure ” means public disclosure of material non-public information, which disclosure in the good faith judgment of the chief financial officer or the general counsel of the Company (i) would be required to be made in any registration statement filed with the Commission by the Company so that such registration statement would not be materially misleading; (ii) would not be required to be made at such time but for the filing of such registration statement and (iii) the Company has a bona fide business purpose for avoiding.

“ Allocation Percentage ” has the meaning set forth in Section 3(b).

“ Commission ” means the United States Securities and Exchange Commission and any agency succeeding to its functions.

“ Common Stock ” means the Class A Common Stock, par value $0.0003-1/3 per share, of the Company.

“ Demand Registration ” has the meaning set forth in Section 2(b).

“ Demand Suspension ” has the meaning set forth in Section 2(e).

“ Holders ” has the meaning set forth in the preamble hereto.

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“ Included Registrable Securities ” has the meaning set forth in Section 3(a).

“ Indemnified Party ” has the meaning set forth in Section 7(c).

“ Indemnifying Party ” has the meaning set forth in Section 7(c).

“ Loss ” has the meaning set forth in Section 7(a).

“ Participant ” has the meaning set forth in Section 7(a).

“ Person ” means a natural person, a partnership, a corporation, a limited liability company, an association, a joint stock company, a trust, a joint venture, an unincorporated organization or other entity, or a governmental entity or any department, agency or political subdivision thereof.

“ Piggyback Registration ” has the meaning set forth in Section 3(a).

“ Registrable Securities ” means each of the Series A Registrable Securities and the Series B Registrable Securities.

“ Securities Act ” means the Securities Act of 1933, as amended, and the rules and regulations of the Commission promulgated thereunder.

“ Securities Exchange Act ” means the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission promulgated thereunder.

“ Series A Demand Registration ” has the meaning set forth in Section 2(a).

“ Series A Exercise Date ” means the date one year after the date hereof.

“ Series A Registrable Securities ” means (1) each share of Common Stock issued upon exercise of the Series A Warrants and owned by the Holders, (2) any Common Stock or other securities issued or issuable to the Holder by way of stock dividend or stock split or in connection with a combination of shares or recapitalization of the Company, (3) any other securities for the shares of Common Stock held by a Holder that may be exchanged or converted in a merger or consolidation (or similar event) of the Company and (4) any securities issued in replacement or exchange of any of the securities issued in clauses (1), (2) or (3) above; provided , however , that any of the foregoing securities shall cease to be “Registrable Securities” to the extent that (i) a registration statement with respect to their sale has been declared effective under the Securities Act and such securities have been disposed of pursuant to such registration statement, (ii) such securities have been distributed pursuant to Rule 144 (or any similar provision then in force) under the Securities Act or (iii) in the opinion of counsel to the Company, such securities are saleable pursuant to Rule 144(k) under the Securities Act.

“ Series A Warrants ” means the warrants generally exercisable for shares of Common Stock starting on the Series A Exercise Date.

“ Series B Demand Registration ” has the meaning set forth in Section 2(b).

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“ Series B Exercise Date ” means the date three years after the date hereof.

“ Series B Registrable Securities ” means (1) each share of Common Stock issued upon exercise of the Series B Warrants and owned by the Holders, (2) any Common Stock or other securities issued or issuable to the Holder by way of stock dividend or stock split or in connection with a combination of shares or recapitalization of the Company, (3) any other securities for the shares of Common Stock held by a Holder that may be exchanged or converted in a merger or consolidation (or similar event) of the Company and (4) any securities issued in replacement or exchange of any of the securities issued in clauses (1), (2) or (3) above; provided , however , that any of the foregoing securities shall cease to be “Registrable Securities” to the extent that (i) a registration statement with respect to their sale has been declared effective under the Securities Act and such securities have been disposed of pursuant to such registration statement, (ii) such securities have been distributed pursuant to Rule 144 (or any similar provision then in force) under the Securities Act or (iii) in the opinion of counsel to the Company, such securities are saleable pursuant to Rule 144(k) under the Securities Act.

“ Series B Warrants ” means the warrants generally exercisable for shares of Common Stock starting on the Series B Exercise Date.

“ Underwritten Offering ” means a registration in which securities of the Company are sold to an underwriter on a firm commitment basis for reoffering to the public.

“ Warrant Agreement ” means the warrant agreement, dated as of the date hereof, between the Company and NFL Properties, setting forth the terms of each of the Series A Warrants and the Series B Warrants.

Whenever used in this Agreement, except as otherwise expressly provided or unless the context otherwise requires, any noun or pronoun shall be deemed to include the plural as well as the singular and to cover all genders. The name assigned this Agreement and the section captions used herein are for convenience of reference only and shall not be construed to affect the meaning, construction or effect hereof. Unless otherwise specified, the terms “hereof,” “herein,” “hereunder” and similar terms refer to this Agreement as a whole, and references herein to Sections refer to Sections of this Agreement.

2. Demand Registrations .

(a) Series A Registrable Securities . Subject to Section 2(f), for a period commencing on the date of exercise of any Series A Warrants and ending on the date one year after the exercise of all or any part of the Series A Warrants, the Holders may make one written request to the Company for registration of all or any part of the Series A Registrable Securities, provided that the estimated market value of the Series A Registrable Securities to be so registered is at least $2,000,000 in the aggregate (based on the current public market price). Any such requested registration shall hereinafter be referred to as a “ Series A Demand Registration .” The request for a Series A Demand Registration shall specify the aggregate amount of Series A Registrable Securities to be registered and the intended methods of disposition thereof.

(b) Series B Registrable Securities . Subject to Section 2(f), for a period commencing on the date of exercise of any Series B Warrants and ending on the date one year

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after the exercise of all or any part of the Series B Warrants, the Holders may make one written request to the Company for registration of all or any part of the Series B Registrable Securities, provided that the estimated market value of the Registrable Securities to be so registered is at least $2,000,000 in the aggregate (based on the current public market price). Any such requested registration shall hereinafter be referred to as a “ Series B Demand Registration ,” and the Series A Demand Registration and the Series B Demand Registration shall each be called a “ Demand Registration .” The request for a Series B Demand Registration shall specify the aggregate amount of Series B Registrable Securities to be registered and the intended methods of disposition thereof.

(c) Demand Registration Procedures

(i) Within 14 days following receipt of any request for a Demand Registration, the Company shall deliver written notice of such request to all other Holders who hold Registrable Securities of the series to be registered. Thereafter, subject to Section 2(e), the Company shall include in such Demand Registration any additional Registrable Securities of such series which the Holder or Holders holding them have requested in writing be included in such Demand Registration, provided that all requests therefor have been received by the Company within 14 days of the Company’s having given the applicable notice to such Holder or Holders pursuant to Section 15. All such requests shall specify the aggregate amount of Registrable Securities to be registered and the intended method of distribution of the same. The Company also may elect to include in such registration additional securities of the class of the Registrable Securities to be registered hereunder, including securities to be sold for the Company’s own account or for the account of Persons who are not Holders.

(ii) As promptly as practicable following receipt of a request for a Demand Registration (but in no event later than 60 days following such receipt), the Company shall use its reasonable best efforts to file a registration statement relating to such Demand Registration, and shall thereafter use its reasonable best efforts to cause such registration statement to be declared effective under the Securities Act and to keep such registration statement effective for not less than 180 days (or such shorter period over which a prospectus is required to be delivered); provided , that any Demand Suspension required pursuant to Section 2(e) hereof during such effective period shall toll such effective period.

(d) Limitation on Demand Registrations; Effective Registration . In no event shall the Company be required to effect more than two Demand Registrations. In addition, the Company shall not be required to file a registration statement for a Demand Registration (i) at any time during the 180-day period following the effective date of another such registration statement for a Demand Registration or (ii) if such registration statement would become effective within 120 days following the effective date of an underwritten offering by the Company that is registered under the Securities Act. A registration will not count as a Demand Registration hereunder until the related registration statement becomes effective and remains effective in compliance with the provisions of Section 2(c)(ii).

(e) Suspension of Registration . If the filing, initial effectiveness or continued use of a registration statement in respect of a Demand Registration at any time would require the Company to make an Adverse Disclosure or would require the inclusion in such registration

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statement of financial statements that are unavailable to the Company, the Company may, upon giving prompt written notice of such action to the Holders holding Registrable Securities included in such Demand Registration, delay the filing or initial effectiveness of, or suspend use of, such registration statement for the shortest period of time determined in good faith by the Company to be necessary for such purpose but in no event longer than 45 days (a “ Demand Suspension ”); provided that there shall be no more than two Demand Suspensions in any 360-day period. In the event of a Demand Suspension, the Holders agree to suspend, immediately upon their receipt of the notice referred to above, any sale or offer to sell the Registrable Securities, and the use of the prospectus related to the Demand Registration in connection with any such sale or offer to sell Registrable Securities, and agree not to disclose to any other Person the fact that the Company has exercised a Demand Suspension or any related facts. The Company shall immediately notify the Holders holding Registrable Securities included in such Demand Registration upon the termination of such Demand Suspension.

(f) Registration Statement Form . Registrations under this Section 2 shall be on such appropriate registration form of the Commission as shall be selected by the Company, so long as such registration form permits the disposition of the Registrable Securities in accordance with the intended method or methods of disposition specified in the applicable Holders’ request for such registration; provided , that if the Company is eligible to register such Registrable Securities pursuant to a registration statement on Form S-3, than the Company shall use such form.

(g) Selection of Underwriter . The Holders of a majority in interest of the Registrable Securities to which a request for a Demand Registration relates shall have the right to select the managing underwriter or underwriters to administer the offering covered by their Demand Registration.

(h) Priority of Demand Registration . If the managing underwriter or underwriters of any proposed Underwritten Offering of securities included in a Demand Registration informs the Holders holding the securities sought to be included in such registration in writing that, in its or their opinion, the total amount or kind of securities which such Holders and the Company intend to include in such offering exceeds the number which can be sold in such offering without being likely to have an adverse effect on the price, timing or distribution of the securities offered or the market for the securities offered, then the securities to be included in such registration shall be allocated as follows:

(i) first, the Registrable Securities requested to be included in such registration statement by the Holders pursuant to this Section 2 pro rata among the Holders requesting such registration based on each such Holder’s Allocation Percentage; and

(ii) second, and only if all the securities referenced in clause (i) have been included, any of such securities held by the Company or any other Person which, in the opinion of such underwriters, can be sold without having such adverse effect shall be included therein.

For the avoidance of doubt, under no circumstances shall such securities owned by the Company be included in a Demand Registration if less than all of the Registrable Securities requested to be included in such registration are so included.

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3. Piggyback Registrations .

(a) Participation .

(i) If the Company at any time proposes to file a registration statement with respect to any offering of securities for its own account or for the account of any holders of its securities (other than (A) a registration under Section 2 hereof, (B) a registration on Form S-4 or S-8 or any successor form to such forms or (C) a registration of securities solely relating to an offering and sale to directors, employees, consultants or suppliers of the Company or any of its subsidiaries pursuant to any current or future plan or employee benefit plan arrangement), then, as soon as practicable (but in no event less than 21 days prior to the proposed date of filing such registration statement), the Company shall give written notice of such proposed filing to all Holders and such notice shall offer the Holders the opportunity to register such number of Registrable Securities as each such Holder may request in writing (a “ Piggyback Registration ”). Subject to Section 4(b), the Company shall include in such registration statement all such Registrable Securities with respect to which the Company has received written requests for inclusion therein within 14 days after the Company’s notice has been given pursuant to Section 15 (“ Included Registrable Securities ”). If at any time after giving written notice of its intention to register any securities and prior to the effective date of the registration statement filed in connection with such registration, the Company shall determine for any reason not to register or to delay registration of such securities, the Company may, at its election, give written notice of such determination to each Holder holding Included Registrable Securities and, (x) in the case of a determination not to register, shall be relieved of its obligation to register any Included Registrable Securities in connection with such registration, and (y) in the case of a determination to delay registering, shall be permitted to delay registering any Included Registrable Securities for the same period as the delay in registering such other securities.

(ii) If the offering pursuant to a Piggyback Registration is to be an Underwritten Offering, then each Holder making a request for its Registrable Securities to be included therein must, and the Company shall make such arrangements with the underwriters so that each such Holder may, participate in such Underwritten Offering on the same terms as other Persons selling securities in such Underwritten Offering. If the offering pursuant to such registration is to be on any other basis, then each Holder making a request for a Piggyback Registration pursuant to this Section 3(a) must participate in such offering on such basis.

(b) Priority of Piggyback Registration . If the managing underwriter or underwriters of any proposed Underwritten Offering of a class of securities included in a Piggyback Registration informs the Holders holding any class sought to be included in such registration in writing that, in its or their opinion, the total amount or kind of securities which such Holders and any other Persons intend to include in such offering exceeds the number which can be sold in such offering without being likely to have an adverse effect on the price, timing or distribution of the class or classes of the securities offered or the market for the class or classes of securities offered, then the securities of each class to be included in such registration shall be allocated as follows:

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4. Black-out Periods

(a) Black-out Periods for Holders . In the event of a registration by the Company involving the offering and sale by the Company of equity securities or securities convertible into or exchangeable for its equity securities, the Holders agree, if requested by the Company (or, in the case of an Underwritten Offering, by the managing underwriter or underwriters), not to effect any public sale or distribution (including any sale pursuant to Rule 144 under the Securities Act) of any securities of the Company (except, in each case, as part of the applicable registration, if permitted) which securities are the same as or similar to those being registered in connection with such registration, or which are convertible into or exchangeable or exercisable for such securities, for the 90-day period commencing on the effective date of the registration statement filed in connection with such registration; provided , that all officers, directors and holders of 5% or more of the Company’s outstanding voting securities enter into agreements providing for similar restrictions on sales or distributions. Notwithstanding the foregoing, (i) any Holder may, during such 90-day period, transfer any Registrable Securities (or other securities) of the Company to any permitted transferee under the terms of the Series A Warrants and the Series B Warrants; provided , that such permitted transferee agrees as a condition to such transfer to abide by the provisions of this Section 4(a), and (ii) the restrictions described in this Section 4(a) shall not prohibit transfers pursuant to plans under Rule 10b5-1 of the Securities Exchange Act existing at the date of such registration by the Company, entered into by any officers, directors, holders of 5% or more of the Company’s outstanding voting securities or the Holders.

(b) Black-out Periods for the Company . In the event of a registration of Registrable Securities pursuant to Section 2 hereof, the Company agrees, if requested by the Holders holding a majority of Registrable Securities to be sold pursuant to such registration (or, in the case of an Underwritten Offering, by the managing underwriter or underwriters in such

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Underwritten Offering), not to effect any public sale or distribution of any securities of the Company which are the same as or similar to those being registered, or which are convertible into or exchangeable or exercisable for such securities, for the 90 day period commencing on the effective date of the registration statement filed in connection with such registration. Notwithstanding the foregoing, the Company may effect a public sale or distribution of securities of the type described above and during the periods described above if the same is (A) part of any registration of securities for offering and sale to directors, employees, consultants or suppliers of the Company or any of its subsidiaries pursuant to any current or future plan or employee benefit plan arrangement or (B) in connection with a direct or indirect acquisition by the Company of another Person.

5. Registration Procedures .

(a) In connection with the Company’s registration obligations pursuant to this Agreement, the Company shall, subject to the limitations set forth herein, use its reasonable best efforts to effect any such registration so as to permit the sale of the applicable Registrable Securities in accordance with the intended method or methods of distribution thereof as expeditiously as reasonably practicable and, in any event, in conformity with any required time period set forth herein, and in connection therewith the Company shall:

(i) before filing a registration statement or a prospectus relating to the Registrable Securities with the Commission, or any amendments or supplements thereto and in connection therewith, or otherwise designating an existing filing with the Commission, furnish to the underwriter or underwriters, if any, and to the Holders of the Registrable Securities covered by such registration statement, copies of all documents prepared to be filed, which documents will be subject to the review of such underwriters and such Holders and their respective counsel;

(ii) prepare and file with the Commission a registration statement relating to the registration on any appropriate form under the Securities Act, or otherwise designating an existing filing with the Commission, which form shall be available for the sale of the Registrable Securities;

(iii) prepare and file with the Commission such amendments or supplements to the applicable registration statement or prospectus used in connection therewith relating to the Registrable Securities as may be (A) reasonably requested by any participating Holder (to the extent such request relates to information relating to such Holder) or (B) necessary to keep such registration effective for the period of time required by this Agreement;

(iv) notify the selling Holders and the managing underwriter or underwriters, if any, as soon as reasonably practicable after notice thereof is received by the Company (A) when the applicable registration statement or any amendment thereto has been filed or becomes effective, or has been otherwise designated and when the applicable prospectus or any amendment or supplement thereto has been filed, (B) of any written comments by the Commission or any request by the Commission for amendments or supplements to such registration statement or prospectus or for additional information, (C) of the issuance by the Commission of any stop order suspending the effectiveness of such registration statement or any order preventing or suspending the use of any preliminary or final prospectus or the initiation or

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threat of any proceedings for such purposes and (D) of the receipt by the Company of any notification with respect to the suspension of the qualification of the Registrable Securities for offering or sale in any jurisdiction or the initiation or threat of any proceeding for such purpose;

(v) promptly notify each selling Holder and the managing underwriter or underwriters, if any, when the Company becomes aware of the happening of any event as a result of which the applicable registration statement or prospectus (as then in effect) relating to the Registrable Securities contains any untrue statement of a material fact or omits to state a material fact necessary to make the statements therein (in the case of the prospectus and any preliminary prospectus, in light of the circumstances under which they were made) not misleading or, if for any other reason it shall be necessary to amend or supplement such registration statement or prospectus in order to comply with the Securities Act and, in either case as promptly as reasonably practicable thereafter, prepare and file with the Commission a post-effective amendment or supplement to such registration statement or prospectus or any document incorporated therein by reference or file any other required document so that, as thereafter delivered to the purchasers of Registrable Securities, the prospectus shall not contain an untrue statement of material fact or omit to state any material fact necessary to make the statements therein not misleading;

(vi) make every reasonable effort to prevent or obtain at the earliest possible moment the withdrawal of any stop order with respect to the applicable registration statement or other order suspending the use of any preliminary or final prospectus relating to the Registrable Securities;

(vii) promptly incorporate in a prospectus supplement or post-effective amendment to the applicable registration statement, if required by applicable law, such information as the managing underwriter or underwriters, if any, or the Holders holding a majority of the Registrable Securities of the class being sold agree should be included therein relating to the plan of distribution with respect to such Registrable Securities, the amount of Registrable Securities being distributed and the purchase price being paid therefor; and make all required filings of such prospectus supplement or post-effective amendment as soon as reasonably practicable after being notified of the matters to be incorporated in such prospectus supplement or post-effective amendment;

(viii) furnish to each selling Holder and each managing underwriter, if any, without charge, as many conformed copies as such Holder or managing underwriter may reasonably request of the applicable registration statement and each amendment and supplement thereto, including all documents incorporated by reference therein or exhibits to such registration statement;

(ix) deliver to each selling Holder and each managing underwriter, if any, without charge, as many copies of the applicable prospectus (including each preliminary prospectus and each prospectus supplement) as such Holder or managing underwriter may reasonably request (it being understood that the Company consents to the use of the prospectus by each of the selling Holders and the underwriter or underwriters, if any, in connection with the offering and sale of the Registrable Securities covered by the prospectus);

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(x) cooperate with the selling Holders and the managing underwriter, underwriters or agent, if any, to facilitate the timely preparation and delivery of certificates representing Registrable Securities to be sold and not bearing any restrictive legends;

(xi) obtain for delivery to the Holders of Registrable Securities being registered and to the underwriter or underwriters, if any, an opinion or opinions from counsel for the Company dated the effective date of the registration statement or, in the event of an Underwritten Offering, the date of the closing under the underwriting agreement, in customary form, scope and substance;

(xii) in the case of an Underwritten Offering, obtain for delivery to the Company and the underwriter or underwriters, if any, with copies to the Holders included in such registration, a comfort letter from the Company’s independent certified public accountants in customary form and covering such matters of the type customarily covered by comfort letters as the managing underwriter or underwriters reasonably request, dated the date of execution of the underwriting agreement and brought down to the closing under the underwriting agreement;

(xiii) cooperate with each selling Holder of Registrable Securities and each underwriter or agent, if any, participating in the disposition of such Registrable Securities and their respective counsel in connection with any filings required to be made with the NASD, Inc.;

(xiv) provide and cause to be maintained a transfer agent and registrar for all Registrable Securities covered by the applicable registration statement from and after a date not later than the effective date of such registration statement;

(xv) cause all Registrable Securities covered by the applicable registration statement to be listed on each securities exchange on which any of the Company’s securities of such class are then listed or quoted and on each inter-dealer quotation system on which any of the Company’s securities of such class are then quoted;

(xvi) make available upon reasonable notice at reasonable times and for reasonable periods for inspection by a representative appointed by the Holders holding a majority of the Registrable Securities of each class covered by the applicable registration statement, by any managing underwriter or underwriters participating in any disposition to be effected pursuant to such registration statement and by any attorney, accountant or other agent retained by such sellers or any such managing underwriter, all pertinent financial and other records, pertinent corporate documents and properties of the Company as shall be reasonably necessary to enable them to exercise their due diligence responsibility, and cause all of the Company’s officers, directors and employees and the independent public accountants who have certified its financial statements to make themselves available to discuss the business of the Company and to supply all information reasonably requested by any such seller, underwriter, attorney, accountant or agent in connection with such registration statement as shall be reasonably necessary to enable them to exercise their due diligence responsibility (subject to the entry by each party referred to in this clause (xvi) into customary confidentiality agreements in a form reasonably acceptable to the Company and NFL Properties);

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(xvii) in the case of an Underwritten Offering, enter into an underwriting agreement as is customary in underwritten offerings, and in connection therewith make such representations and warranties to the underwriters, with respect to the business of the Company and its subsidiaries and the registration statement, prospectus and documents, if any, incorporated or deemed incorporated by reference therein, in each case, at such times and in such scope as are customarily made by issuers to underwriters in underwritten public offerings; and

(xviii) register and qualify the securities covered by any registration statement filed with the Commission pursuant to this Agreement under such other securities or “Blue Sky” laws of such jurisdictions as shall be reasonably requested by the Holders, to keep such registration or qualification in effect for so long as such registration remains in effect, and take any other action which may be reasonably necessary or advisable to enable the Holder of Registrable Securities to be sold under such registration statement to consummate the disposition in such jurisdictions of the securities owned by such Holder; provided, that the Company shall not for any such purpose be required to (A) qualify generally to do business as a foreign corporation in any jurisdiction wherein it would not but for the requirements of this Section 5.3(a)(xviii) be obligated to be so qualified or (ii) subject itself to taxation in any such jurisdiction.

(b) The Company may require each selling Holder as to which any registration is being effected to furnish to the Company such information regarding the distribution of such Holders’ Registrable Securities and such other information relating to such Holder and its ownership of the applicable Registrable Securities as the Company may from time to time reasonably request. Each Holder agrees to furnish such information to the Company and to cooperate with the Company as necessary to enable the Company to comply with the provisions of this Agreement. The Company shall have the right to exclude any Holder that does not comply with the preceding sentence from the applicable registration.

(c) Each Holder agrees by acquisition of its Registrable Securities that, upon receipt of any notice from the Company of the happening of any event of the kind described in Section 5(a)(iv), such Holder shall discontinue disposition of its Registrable Securities pursuant to such registration statement until such Holder’s receipt of the copies of the supplemented or amended prospectus contemplated by Section 5(a)(iv) and of any additional or supplemental filings that are incorporated by reference in the prospectus or until such Holder is advised in writing by the Company that the use of the prospectus may be resumed, and has received copies and, if so directed by the Company, such Holder shall deliver to the Company (at the Company’s expense) all copies, other than permanent file copies then in such Holder’s possession, of the prospectus covering such Registrable Securities which are current at the time of the receipt of such notice.

6. Registration Expenses. The Company shall pay all expenses incident to the Company’s performance of or compliance with this Agreement, including without limitation: (i) all registration and filing fees, and any other fees and expenses associated with filings required to be made with the Commission or the NASD, Inc., (ii) all fees and expenses of compliance with state securities or “Blue Sky” laws (including without limitation reasonable and documented fees and disbursements of counsel for any underwriters in connection with “Blue Sky” qualifications of the Registrable Securities, (iii) all of its printing, duplicating, word

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processing, messenger, telephone, facsimile and delivery expenses (including expenses of printing certificates for the Registrable Securities in a form eligible for deposit with The Depository Trust Company and of printing prospectuses), (iv) all fees and disbursements of counsel for the Company and of all independent certified public accountants of the Company (including without limitation the expenses of any annual audit, special audit and “cold comfort” letters required by or incident to such performance and compliance), (v) Securities Act liability insurance or similar insurance if the Company so desires or the underwriter or underwriters, if any, so require in accordance with then-customary underwriting practice, (vi) all fees and expenses incurred in connection with the listing of the Registrable Securities on any securities exchange or the quotation of the Registrable Securities on any inter-dealer quotation system, (vii) all applicable rating agency fees with respect to any applicable Registrable Securities, (viii) the fees and disbursements of underwriters (including without limitation all fees and expenses of any “qualified independent underwriter” required by the rules of the NASD and fees and expenses of counsel to such qualified independent underwriter) customarily paid by issuers or sellers of securities in public equity offerings, and (ix) the expenses customarily borne by issuers of securities in a “road show” presentation to potential investors. In addition, the Company shall pay its internal expenses (including, without limitation, all salaries and expenses of its officers and employees performing legal or accounting duties), the expense of any audit and the fees and expenses of any Person, including special experts, retained by the Company. The Company shall not be required to pay any underwriting discounts or commissions or transfer taxes attributable to the sale of Registrable Securities. In addition, and notwithstanding anything in this Section 6 to the contrary, other than as specifically set forth in clause (viii), (A) in the event of a registration under Section 2, neither the Company nor NFL Properties shall be responsible for the payment of any expenses of counsel to such underwriters and (B) in the event of a registration under Section 3, NFL Properties shall not be responsible for the payment of any expenses of counsel to such underwriters.

7. Indemnification .

(a) Indemnification by the Company . The Company agrees to indemnify and hold harmless, to the full extent permitted by law, each Holder selling Registrable Securities and its respective officers, directors and employees and each Person who controls (within the meaning of the Securities Act or the Securities Exchange Act) such selling Holder (each, a “ Participant ”) from and against any and all losses, claims, damages, judgments, liabilities and expenses (including reasonable costs of investigation and legal expenses) caused by (i) any untrue or alleged untrue statement of a material fact contained in any registration statement under which such Registrable Securities were registered under the Securities Act (including any final, preliminary or summary prospectus contained therein relating to the Registrable Securities or any amendment thereof or supplement thereto or any documents incorporated by reference therein) or (ii) any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein (in the case of a prospectus or preliminary prospectus, in light of the circumstances under which they were made) not misleading (each, a “ Loss ” and collectively “ Losses ”); provided , however , that the Company shall not be liable to any Participant in any such case to the extent that any such Loss is caused by written information furnished to the Company by such Holder for use in the preparation thereof and stated to be specifically for use therein, or if such untrue statement or alleged untrue statement or omission or alleged omission is corrected in an amendment or supplement to such prospectus which has been

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made available to the Holders and the relevant Holder fails to deliver such prospectus as so amended or supplemented, if such delivery is required under applicable law or the applicable rules of any securities exchange, prior to or concurrently with the sales of the Registrable Securities to the Person asserting such Loss. This indemnity shall be in addition to any liability the Company may otherwise have.

(b) Indemnification by the Holders . Each selling Holder agrees (severally and not jointly) to indemnify and hold harmless, to the fullest extent permitted by law, the Company, its directors, officers and employees and each Person who controls the Company (within the meaning of the Securities Act and the Securities Exchange Act) from and against any Loss to the extent, but only to the extent, that such Loss is caused by any information furnished in writing by such selling Holder to the Company for inclusion in such registration statement and was not corrected in a subsequent writing prior to or concurrently with the sale of the Registrable Securities to the Person asserting such Loss. This indemnity shall be in addition to any liability such Holder may otherwise have.

(c) Indemnification Proceedings . Any Person entitled to indemnification hereunder (an “ Indemnified Party ”) shall (i) give prompt written notice to the Person from whom such indemnification may be sought (the “ Indemnifying Party ”) of any claim with respect to which it seeks indemnification, provided , however , that the failure to so notify the Indemnifying Party shall not relieve it of any obligation or liability which it may have hereunder or otherwise except to the extent it is materially prejudiced by such failure, and (ii) permit such Indemnifying Party to assume the defense of such claim with counsel reasonably satisfactory to the Indemnified Party; provided , however , that the Indemnified Party shall have the right to select and employ separate counsel and to participate in the defense of such claim, but the fees and expenses of such counsel shall be at the expense of the Indemnified Party unless (A) the Indemnifying Party has agreed in writing to pay such fees or expenses, (B) the Indemnifying Party shall have failed to assume the defense of such claim within a reasonable time after having received notice of such claim from the Indemnified Party and to employ counsel reasonably satisfactory to the Indemnified Party or (C) in the reasonable judgment of the Indemnified Party, based upon advice of its counsel, a conflict of interest exists between the Indemnified Party and the Indemnifying Party with respect to such claims or the Indemnified Party has material defenses separate and apart from the defenses of the Indemnifying Party with respect to such claims (in which case, if the Indemnified Party notifies the Indemnifying Party in writing that the Indemnified Party elects to employ separate counsel at the expense of the Indemnifying Party, the Indemnifying Party shall not have the right to assume the defense of such claim on behalf of the Indemnified Party). If such defense is assumed by the Indemnifying Party (or if the Indemnifying Party’s failure to assume such defense is due to the Indemnified Party’s invocation of subsection (C) of the immediately preceding sentence), the Indemnifying Party shall not be subject to any liability for any settlement made without its consent, but such consent may not be unreasonably withheld; provided , that an Indemnifying Party shall not be required to consent to any settlement involving the imposition of equitable remedies or involving the imposition of any material obligations on such Indemnifying Party other than financial obligations for which such Indemnified Party will be indemnified hereunder. If the Indemnifying Party assumes the defense, the Indemnifying Party shall have the right to settle such action without the consent of the Indemnified Party; provided , that the Indemnifying Party shall be required to obtain such consent (which consent shall not be unreasonably withheld) if the settlement includes any

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admission of wrongdoing on the part of the Indemnified Party or any equitable remedies or restriction on the Indemnified Party or its officers, directors or employees. No Indemnifying Party shall consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by the claimant or plaintiff to each Indemnified Party of an unconditional release from all liability in respect to such claim or litigation. An Indemnifying Party (or, as the case may be, Indemnifying Parties) shall not, in connection with any proceeding or related proceedings in the same jurisdiction, be liable for the reasonable fees, disbursements and other charges of more than one separate firm admitted to practice in such jurisdiction at any one time from all Indemnified Parties collectively unless (x) the employment of more than one counsel has been authorized in writing by such Indemnifying Party (or Indemnifying Parties) or (y) a conflict exists or may exist (based on advice of counsel to an Indemnified Party) between such Indemnified Party and other Indemnified Parties, in each of which cases the Indemnifying Party (or Indemnifying Parties) shall be obligated to pay the reasonable fees and expenses of such additional counsel or counsels. The indemnification provided for under this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of the Indemnified Party or any officer, director or controlling Person of such Indemnified party and shall survive the transfer of securities. (d)  Contribution . If for any reason the indemnification provided for in paragraphs (a) and (b) of this Section 7 is unavailable to an Indemnified Party or insufficient to hold it harmless as contemplated by paragraphs (a) and (b) of this Section 7, then the Indemnifying Party shall contribute to the amount paid or payable by the Indemnified Party as a result of such Loss in such proportion as is appropriate to reflect the relative fault of the Indemnifying Party on the one hand and the Indemnified Party on the other. 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 Indemnifying Party or the Indemnified Party and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The parties hereto agree that it would not be just and equitable if contribution pursuant to this Section 7(d) were determined by pro rata allocation or by any other method of allocation that does not take account of the equitable considerations referred to in the immediately preceding paragraph. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation. If indemnification is available under this Section 7, the Indemnifying Parties shall indemnify each Indemnified Party to the full extent provided in Sections 7(a) and 7(b) hereof without regard to the relative fault of said Indemnifying Parties or Indemnified Party.

(e) Limitation on Liability of Holders of Registrable Securities . The liability of any Holder in respect of any indemnification or contribution obligation arising under this Section 7 shall not in any event exceed an amount equal to the total proceeds (net of any exercise price of the Series A Warrants or the Series B Warrants and after deduction of all underwriters’ discounts and commissions and all other expenses paid by such Holder in connection with the registration in question) from the disposition of the Registrable Securities disposed of by the Holder pursuant to such registration.

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8. Compliance with Rule 144 .

(a) The Company shall file the reports required to be filed by it under the Securities Act and the Securities Exchange Act so long as the Company is obligated to file such reports, and it shall take such further action as any Holder may reasonably request, all to the extent required from time to time to enable such Holder to sell Registrable Securities without registration under the Securities Act within the limitation of the exemptions provided by (a) Rule 144 under the Securities Act, as such Rule may be amended from time to time, or (b) any similar rules or regulations hereafter adopted by the Commission. Upon the written request of any Holder, the Company shall deliver to such Holder a written statement as to whether it has complied with such requirements.

(b) The Company covenants and agrees to promptly remove (or cause to be removed) any legends on any certificates evidencing Registrable Securities and any stop transfer instructions relating thereto in connection with a transfer of Registrable Securities (i) in a public offering effected pursuant to a registration contemplated by this Agreement or (ii) if, in the opinion of counsel reasonably satisfactory to the Company to any Holder, such Holder is entitled to transfer the Registrable Securities without registration.

9. Underwriting Agreements . The Holders holding any Registrable Securities to be included in any Underwritten Offering pursuant to Section 3 shall enter into such an underwriting agreement at the request of the Company. No Holder shall be required in any such underwriting agreement to make any representations or warranties to or agreements with the Company or the underwriters other than representations, warranties or agreements regarding such Holder, such Holder’s Registrable Securities, such Holder’s intended method of distribution and any other representations required by law.

10. Term . This Agreement, and all registration rights pursuant thereto, shall terminate upon the earlier to occur of (i) five years from the date hereof or (ii) the first time at which there are no Registrable Securities outstanding.

11. Amendments and Waivers . The provisions of this Agreement may be amended or waived at any time only by the written agreement of the Company and NFL Properties. Any waiver, permit, consent or approval of any kind or character on the part of either party to this Agreement of any provision or condition of this Agreement must be made in writing and shall be effective only to the extent specifically set forth in writing.

12. Successors, Assigns and Transferees .

(a) The registration rights of any Holder under this Agreement with respect to any Registrable Securities may be transferred and assigned, provided that such rights may only be transferred or assigned to another Holder or to any permitted transferee under the terms of the Series A Warrants and the Series B Warrants, and, provided further , that no such transfer or assignment shall be binding upon or obligate the Company to any such transferee or assignee unless and until the Company shall have received notice of such transfer or assignment as herein provided and a written agreement of the transferee or assignee to be bound by the provisions of this Agreement as a “Holder”. Any transfer or assignment made other than as provided in the first sentence of this Section 12 shall be null and void.

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(b) This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, and their respective successors and permitted assigns.

13. Final Agreement . This Agreement constitutes the final agreement of the parties concerning the matters referred to herein, and supersedes all prior agreements and understandings.

14. Severability . Whenever possible, each provision of this Agreement will be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Agreement is held to be prohibited by or invalid under applicable law, such provision will be ineffective only to the extent of such prohibition or invalidity, without invalidating the remainder of this Agreement.

15. Notices . All notices, demands or other communications or documents to be given or delivered under or by reason of the provisions of this Agreement shall be made in writing and shall be deemed to have been given (a) when delivered personally to the recipient; (b) when sent to the recipient by telecopy (receipt electronically confirmed by sender’s telecopy machine) if during normal business hours of the recipient, otherwise on the next business day; (c) one business day after the date when sent to the recipient by reputable express courier service (charges prepaid) or (d) seven business days after the date when mailed to the recipient by certified or registered mail, return receipt requested and postage prepaid. Such notices, demands and other communications shall be sent to the parties at the addresses indicated below, or to such other address as either party hereto may, from time to time, designate in writing delivered pursuant to the terms of this Section 15:

If to the Holders, to:

NFL Properties LLC

280 Park Avenue

New York, NY 10017

Attention: Gary Gertzog

With a copy to:

Covington & Burling LLP

1201 Pennsylvania Avenue, N.W.

Washington, D.C. 20004

Attention: Bruce Wilson

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If to the Company, to:

Under Armour, Inc.

1020 Hull Street, 3rd Floor

Baltimore, Maryland 21230

Attention: General Counsel

With a copy to:

Cleary Gottlieb Steen & Hamilton LLP

One Liberty Plaza

New York, NY 10006

Attn: Stephen H. Shalen, Esq.

16. Governing Law; Service of Process; Consent to Jurisdiction . (a) THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS MADE AND TO BE PERFORMED WITHIN THE STATE.

(b) To the fullest extent permitted by applicable law, each party hereto (i) agrees that any claim, action or proceeding by such party seeking any relief whatsoever arising out of, or in connection with, this Agreement or the transactions contemplated hereby shall be brought only in the U.S. District Court for the Southern District of New York and in any New York State court located in the Borough of Manhattan and not in any other State or Federal court in the United States of America or any court in any other country, (ii) agrees to submit to the exclusive jurisdiction of such courts located in the State of New York for purposes of all legal proceedings arising out of, or in connection with, this Agreement or the transactions contemplated hereby and (iii) irrevocably waives any objection which it may now or hereafter have to the laying of the venue of any such proceeding brought in such a court and any claim that any such proceeding brought in such a court has been brought in an inconvenient forum.

17. Counterparts and Facsimile Execution . This Agreement may be executed in any number of counterparts, each of which when so executed and delivered shall be deemed an original, and such counterparts together shall constitute one instrument. This agreement may be executed by the exchange of signatures by facsimile transmission. Each party shall receive a duplicate original of the counterpart copy or copies executed by it and the Company.

18. No Inconsistent Agreements . The Company shall not, on or after the date of this Agreement, enter into any agreement with respect to its securities that is inconsistent with the rights granted to the Holders in this Agreement. The rights granted to the Holders hereunder are not inconsistent with the rights granted to the holders of the Company’s securities under any agreement in effect on the date hereof.

19. Severability . In the event that any one or more of the provisions contained herein, or the application thereof in any circumstances, is held invalid, illegal or unenforceable in any respect for any reason, the validity, legality and enforceability of any such provision in every

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other respect and of the remaining provisions hereof shall not be in any way impaired or affected thereby, it being intended that all of the rights and privileges of the parties shall be enforceable to the fullest extent permitted by law.

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

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