In connection with an arrangement agreement (the “Arrangement Agreement”) dated December 7, 2025 between Contango, the Acquiror and Dolly Varden Silver Corporation (the “Company”), the Acquiror is to issue exchangeable shares (the “Exchangeable Shares”) to certain holders of common shares of the Company pursuant to an arrangement under Division 5 of Part 9 of the BCBCA (the “Arrangement”) on the terms and conditions set out in the Plan of Arrangement.

Pursuant to the Arrangement Agreement, and as a step in the Plan of Arrangement, Contango, CallCo and the Acquiror are required to enter into an exchangeable share support agreement (this “Agreement”).

In connection with the Plan of Arrangement, it is necessary and advisable to provide Contango and CallCo with the rights herein with respect to the Exchangeable Shares.

References in this Agreement to the words “include”, “includes” or “including” shall be deemed to be followed by the words “without limitation” whether or not they are in fact followed by those words or words of like import.

References in this Agreement to any contract or agreement are to that contract or agreement as amended, modified or supplemented from time to time in accordance with the terms hereof and thereof.

References in this Agreement to a Person includes the heirs, administrators, executors, legal personal representatives, predecessors, successors and permitted assigns of that Person, as applicable.

not take any action that will result in the declaration or payment of any dividend or make any other distribution on the Contango Shares unless the Acquiror shall (A) simultaneously declare or pay, as the case may be, an equivalent dividend or other distribution economically equivalent thereto (as determined in accordance with the Exchangeable Share Provisions) on the Exchangeable Shares (an “Equivalent Dividend”), (B) in the case of a cash dividend or other distribution, receive sufficient money or other assets from Contango (through any intermediary entities) to enable the due declaration and the due and punctual payment, in accordance with applicable law and the Exchangeable Share Provisions, of any such Equivalent Dividend, and (C) in the case of a dividend or other distribution that is a stock or share dividend or a distribution of stock or shares, have sufficient authorized but unissued securities available to enable the due declaration and the due and punctual payment, in accordance with applicable law and the Exchangeable Share Provisions, of any such Equivalent Dividend; provided however, for the avoidance of doubt, that in no event may the Acquiror elect to effect a dividend or other distribution that is a stock or share dividend or a distribution of stock or shares in the form of cash or property other than stock or shares;

advise the Acquiror sufficiently in advance of the declaration by Contango of any dividend or other distribution on the Contango Shares and take all such other actions as are reasonably necessary or desirable, in co-operation with the Acquiror, to ensure that (A) the respective declaration date, record date and payment date for an Equivalent Dividend shall be the same as the declaration date, record date and payment date for the corresponding dividend or other distribution on the Contango Shares; and (B) the record date for any dividend or other distribution declared on the Contango Shares is not less than 10 Business Days

after the declaration date of such dividend or declaration in each case provided that, if the record date for the dividend or other distribution declared on or in respect of the Contango Shares is more than two (2) months from the date such dividend or other distribution is paid, then the record date in connection with the payment of the dividend or other distribution declared on the Exchangeable Shares shall be two (2) months prior to the payment of such dividend or other distribution;

take all such actions and do all such things as are reasonably necessary or desirable to enable and permit the Acquiror, in accordance with applicable law, to pay and otherwise perform its obligations with respect to the satisfaction of the Liquidation Amount, the Retraction Price or the Redemption Price in respect of each issued and outstanding Exchangeable Share upon the liquidation, dissolution or winding-up of the Acquiror, whether voluntary or involuntary, or any other distribution of the assets of the Acquiror among its shareholders for the purpose of winding up its affairs, the delivery of a Retraction Request by a holder of Exchangeable Shares or a redemption of Exchangeable Shares by the Acquiror, as the case may be, including, without limitation, all such actions and all such things as are necessary or desirable to enable and permit the Acquiror to deliver or cause to be delivered Contango Shares or other property to the holders of Exchangeable Shares in accordance with the provisions of Sections 27.5, 27.6 or 27.7, as the case may be, of the Exchangeable Share Provisions;

take all such actions and do all such things as are reasonably necessary or desirable to enable and permit the Trustee, in accordance with applicable law, to perform its obligations under the Voting and Exchange Trust Agreement, including, without limitation, all such actions and all such things as are reasonably necessary or desirable to enable and permit the Trustee in its capacity as trustee under the Voting and Exchange Trust Agreement to exercise voting rights in respect of a Contango Meeting (as such term is defined in the Voting and Exchange Trust Agreement) as provided for therein;

take all such actions and do all such things as are necessary or desirable to enable and permit Contango or CallCo, as the case may be, in accordance with applicable law, to perform its obligations arising upon the exercise by it of the Liquidation Call Right, the Retraction Call Right, the Change of Law Call Right or the Redemption Call Right, including, without limitation, all such actions and all such things as are necessary or desirable to enable and permit Contango or CallCo, as the case may be, to deliver or cause to be delivered Contango Shares or other property to the holders of Exchangeable Shares in accordance with the provisions of the Liquidation Call Right, the Retraction Call Right, the Change of Law Call Right or the Redemption Call Right, as the case may be;

take all such actions and do all such things as are reasonably necessary or desirable to enable and permit Contango, in accordance with applicable law, to perform its obligations in connection with a Retraction Request pursuant to Section 27.6 of the Exchangeable Share Provisions and the redemption by the Acquiror pursuant to Section 27.7 of the Exchangeable Share Provisions, including, without limitation, all such actions and all such things as are necessary or desirable to enable and permit Contango to deliver or cause to be delivered Contango Shares or other property to the holders of Exchangeable Shares in accordance with the provisions of Sections 27.6 or 27.7 of the Exchangeable Share Provisions; and

not and shall ensure that it and its affiliates do not exercise any voting rights as a shareholder of the Acquiror to initiate the voluntary liquidation, dissolution or winding up of the Acquiror or any other distribution of the assets of the Acquiror among its shareholders for the purpose of winding up its affairs, nor take any action or omit to take any action that is designed to result in the liquidation, dissolution or winding up of the Acquiror or any other distribution of the assets of the Acquiror among its shareholders for the purpose of winding up its affairs, without the prior approval of the holders of the Exchangeable Shares in accordance with the Exchangeable Share Provisions as long as any Exchangeable Shares are outstanding.

as is equal to the sum of (i) the number of Exchangeable Shares issued and outstanding from time to time, and (ii) the number of Exchangeable Shares issuable upon the exercise of all rights to acquire Exchangeable Shares outstanding from time to time; and

as are now and may hereafter be required to enable and permit each of Contango, CallCo and the Acquiror to meet its obligations under the Voting and Exchange Trust Agreement, the Exchangeable Share Provisions and any other security or commitment relating to the Arrangement pursuant to which Contango may now or hereafter be required to issue or cause to be issued Contango Shares.

in the event of any determination by the board of directors of the Acquiror to institute voluntary liquidation, dissolution or winding-up proceedings with respect to the Acquiror or to effect any other distribution of the assets of the Acquiror

among its shareholders for the purpose of winding up its affairs, at least 60 days prior to the proposed effective date of such liquidation, dissolution, winding-up or other distribution;

promptly upon the earlier of (i) receipt by the Acquiror of notice of, and (ii) the Acquiror otherwise becoming aware of, any threatened or instituted claim, suit, petition or other proceedings with respect to the involuntary liquidation, dissolution or winding-up of the Acquiror or to effect any other distribution of the assets of the Acquiror among its shareholders for the purpose of winding up its affairs;

immediately, upon receipt by the Acquiror of a Retraction Request;

on the same date on which notice of redemption is given to holders of Exchangeable Shares, upon the determination of a Redemption Date in accordance with the Exchangeable Share Provisions;

as soon as practicable upon the issuance by the Acquiror of any Exchangeable Shares or rights to acquire Exchangeable Shares (other than the issuance of Exchangeable Shares and rights to acquire Exchangeable Shares pursuant to the Arrangement); and

promptly, upon receiving notice of a Change of Law.

Contango covenants and agrees that it will use reasonable best efforts to (A) file a registration statement (the “Registration Statement”) on Form S-3 (or any successor or other applicable form) under the U.S. Securities Act of 1933, as amended (the “1933 Act”) to register the Contango Shares to be issued or delivered to holders of the Exchangeable Shares by Contango or CallCo (including, for greater certainty, pursuant to the Exchange Right, as that term is defined in the Voting and Exchange Trust Agreement, or the Automatic Exchange Right) by or as promptly as practicable after the Effective Date, and (B) cause such registration statement to become effective as promptly as practicable after such filing and to maintain the effectiveness of such registration statement (or any appropriate replacement registration statement) for so long as any Exchangeable Shares remain outstanding. Without limiting the generality of the foregoing, Contango and CallCo each covenant and agree that it will take all such actions and do all such things as are reasonably necessary or desirable to make such filings and seek such regulatory consents and approvals as are necessary so that the Contango Shares to be issued or delivered to holders of Exchangeable Shares pursuant to the terms of the Exchangeable Share Provisions, the Voting and Exchange Trust Agreement and this Agreement will be offered,

sold, issued and delivered in compliance with the 1933 Act and all applicable state securities laws, and applicable securities laws in Canada and will not be subject to any hold period as contemplated by Rule 144 under the 1933 Act or subject to any “hold period” resale restriction under National Instrument 45-102 Resale of Securities. Contango will use its reasonable best efforts to cause all Contango Shares to be delivered to holders of Exchangeable Shares pursuant to the terms of the Exchangeable Share Provisions, the Voting and Exchange Trust Agreement and this Agreement to be listed, quoted and posted for trading on all stock exchanges and quotation systems on which outstanding Contango Shares have been listed by Contango and remain listed and are quoted or posted for trading at such time.

Notwithstanding any other provision of the Exchangeable Share Provisions, or any term of this Agreement, the Voting and Exchange Trust Agreement or the Plan of Arrangement, no Contango Shares shall be issued (and Contango will not be required to issue any Contango Shares) in connection with any liquidation, dissolution or winding-up of the Acquiror, or any retraction, redemption or any other exchange, direct or indirect, of Exchangeable Shares, if such issuance of Contango Shares would not be permitted by applicable laws.

So long as any Exchangeable Shares not owned by Contango or its affiliates are outstanding:

Contango shall not without the prior approval of the Acquiror and the prior approval of the holders of the Exchangeable Shares given in accordance with Section 27.10(b) of the Exchangeable Share Provisions:

issue or distribute Contango Shares (or securities exchangeable for or convertible into or carrying rights to acquire Contango Shares) to the holders of all or substantially all of the then outstanding Contango Shares by way of stock or share dividend or other distribution, other than an issue of Contango Shares (or securities exchangeable for or convertible into or carrying rights to acquire Contango Shares) to holders of Contango Shares (A) who exercise an option to receive dividends in Contango Shares (or securities exchangeable for or convertible into or carrying rights to acquire Contango Shares) in lieu of receiving cash dividends, or (B) pursuant to any dividend reinvestment plan or scrip dividend or similar arrangement; or

issue or distribute rights, options or warrants to the holders of all or substantially all of the then outstanding Contango Shares entitling them to subscribe for or to purchase Contango Shares (or securities exchangeable for or convertible into or carrying rights to acquire Contango Shares); or

issue or distribute to the holders of all or substantially all of the then outstanding Contango Shares (A) shares or securities of Contango of any class other than Contango Shares (or securities convertible into or exchangeable for or carrying rights to acquire Contango Shares), (B) rights, options, warrants or other assets other than those referred to in Section 2.7(1)(a)(ii), (C) evidence of indebtedness of Contango or (D) assets of Contango;

unless, in each case, the Acquiror issues or distributes the economic equivalent of such rights, options, warrants, securities, shares, evidences of indebtedness or other assets simultaneously to holders of the Exchangeable Shares; provided, however, that, for greater certainty, the above restrictions shall not apply to any securities issued or distributed by Contango in order to give effect to and to consummate the transactions contemplated by, and in accordance with, the Arrangement Agreement and the Plan of Arrangement.

Contango shall not without the prior approval of the Acquiror and the prior approval of the holders of the Exchangeable Shares given in accordance with Section 27.10(b) of the Exchangeable Share Provisions:

subdivide, redivide or change the then outstanding Contango Shares into a greater number of Contango Shares; or

reduce, combine, consolidate or change the then outstanding Contango Shares into a lesser number of Contango Shares; or

reclassify or otherwise change the Contango Shares or effect an amalgamation, merger, reorganization or other transaction affecting the Contango Shares;

Contango shall ensure that the record date for any event referred to in Section 2.7(1)(a) or Section 2.7(1)(b), or (if no record date is applicable for such event) the effective date for any such event, is not less than five Business Days after the date on which such event is declared or announced by Contango (with contemporaneous notification thereof by Contango to the Acquiror).

The board of directors of the Acquiror shall determine, in good faith and in its sole discretion (with the assistance of such financial or other advisors as the board of directors may determine), “economic equivalence” for the purposes of any event referred to in Section 2.7(1)(a) or Section 2.7(1)(b) and each such determination shall be conclusive and binding on Contango, absent manifest error. In making each such determination, the following factors shall, without excluding other factors determined by the board of directors of the Acquiror to be relevant, be considered by the board of directors of the Acquiror:

in the case of any stock or share dividend or other distribution payable in Contango Shares, the number of such shares issued as a result of such stock or share dividend or other distribution in proportion to the number of Contango Shares previously outstanding;

in the case of the issuance or distribution of any rights, options or warrants to subscribe for or purchase Contango Shares (or securities exchangeable for or convertible into or carrying rights to acquire Contango Shares), the relationship between the exercise price of each such right, option or warrant, the number of such rights, options or warrants to be issued or distributed in respect of each Contango Share and the Current Market Price of a Contango Share, the price volatility of the Contango Shares and the terms of any such instrument;

in the case of the issuance or distribution of any other form of property (including, without limitation, any shares or securities of Contango of any class other than Contango Shares, any rights, options or warrants other than those referred to in Section 2.7(2)(b), any evidences of indebtedness of Contango or any assets of Contango), the relationship between the fair market value (as determined by the board of directors of the Acquiror in the manner above contemplated) of such property to be issued or distributed with respect to each outstanding Contango Share and the Current Market Price of a Contango Share;

in the case of any subdivision, redivision or change of the then outstanding Contango Shares into a greater number of Contango Shares or the reduction, combination, consolidation or change of the then outstanding Contango Shares into a lesser number of Contango Shares or any amalgamation, merger, arrangement, reorganization or other transaction affecting Contango Shares, the effect thereof upon the then outstanding Contango Shares; and

in all such cases, the general taxation consequences of the relevant event to holders of Exchangeable Shares to the extent that such consequences may differ from the taxation consequences to holders of Contango Shares as a result of differences between taxation laws of Canada and the United States (except for any differing consequences arising as a result of differing marginal taxation rates and without regard to the individual circumstances of holders of Exchangeable Shares).

The Acquiror agrees that, to the extent required, upon due notice from Contango, the Acquiror shall take or cause to be taken such steps as may be necessary for the purposes of ensuring that appropriate dividends are paid or other distributions are made by the Acquiror, or subdivisions, redivisions or changes are made to the Exchangeable Shares, in order to implement the required economic equivalence with respect to the Contango Shares and Exchangeable Shares as provided for in this Section 2.7.

such other Person or continuing corporation (the “Contango Successor”) by operation of law, becomes, without more, bound by the terms and provisions of this Agreement or, if not so bound, executes, prior to or contemporaneously with the consummation of such transaction, an agreement supplemental hereto and such other instruments (if any) as are necessary or advisable to evidence the assumption by the Contango Successor of liability for all moneys payable and property deliverable hereunder and the covenant of such Contango Successor to pay and deliver or cause to be paid and delivered the same and its agreement to observe and perform all the covenants and obligations of Contango under this Agreement; and

such transaction shall be upon such terms and conditions as to preserve and not to impair any of the rights, duties, powers and authorities of the other parties hereunder or the holders of the Exchangeable Shares.

in which Contango merges, combines or amalgamates with, or in which all or substantially all of the then outstanding Contango Shares are acquired by, one or more other corporations to which Contango is, immediately before such merger, combination, amalgamation or acquisition, “related” within the meaning of the Tax Act (otherwise than by virtue of a right referred to in paragraph 251(5)(b) thereof) or any analogous provision under the Code;

which does not result in an acceleration of the Redemption Date in accordance with paragraph (ii) of the definition of Redemption Date in the Exchangeable Share Provisions; and

in which all or substantially all of the then outstanding Contango Shares are converted into or exchanged for shares or rights to receive such shares (the “Other Shares”) of another corporation (the “Other Corporation”) that, immediately after such Contango Extraordinary Transaction, owns or controls, directly or indirectly, Contango;

adding to the covenants of any or all of the parties hereto if the board of directors of each of Contango, CallCo and the Acquiror shall be of the good faith opinion that such additions will not be prejudicial to the rights or interests of the holders of the Exchangeable Shares;

evidencing the succession of Contango Successors and the covenants of and obligations assumed by each such Contango Successor in accordance with the provisions of Article 3;

making such amendments or modifications not inconsistent with this Agreement as may be necessary or desirable with respect to matters or questions arising hereunder which, in the good faith opinion of the board of directors of each of Contango, CallCo and the Acquiror, it may be expedient to make, provided that each such board of directors shall be of the good faith opinion, after consultation with counsel, that such amendments or modifications will not be prejudicial to the rights or interests of the holders of the Exchangeable Shares; or

making such changes or corrections hereto which, on the advice of counsel to Contango, CallCo and the Acquiror, are required for the purpose of curing or correcting any ambiguity or defect or inconsistent provision or clerical omission or mistake or manifest error contained herein, provided that the boards of directors of each of Contango, CallCo and the Acquiror shall be of the good faith opinion that such changes or corrections will not be prejudicial to the rights or interests of the holders of the Exchangeable Shares.

In the case of Contango, CallCo or the Acquiror at the following address: