STOCKHOLDER AGREEMENT

Exhibit 4.1

STOCKHOLDER AGREEMENT

AND

NATIONAL MEDICAL HEALTH CARD SYSTEMS, INC.

DATED AS OF FEBRUARY 25, 2008

INDEX OF DEFINED TERMS

		Page
Agreement			1
Beneficial Ownership			2
Beneficially Own			2
Beneficially Owned			2
Claims			11
Company			1
Company Common Stock			1
Company Convertible Preferred Stock			1
Company Stock			1
Covered Shares			2
Depositary			3
Encumbrance			2
Existing Shares			2
Fundamental Amendment			13
Grantees			5
Lock-Up Period			8
Meeting Right			12
Merger			1
Merger Agreement			1
Merger Sub			1
Offer			1
Operative Date			2
Other Stockholder			2
Parent			1
Prohibited Activity			11
Registration Rights Agreement			8
Releasees			11
Section 3.1(a) Matters			5
Stockholder			1
Tender Documents			3
Traded Securities			11
Transfer			2
US Corp.			1
Valuation Period			11

STOCKHOLDER AGREEMENT

          STOCKHOLDER AGREEMENT, dated as of February 25, 2008 (this “ Agreement ”), by and among SXC Health Solutions Corp., a corporation organized under the laws of Yukon Territory, Canada (“ Parent ”), New Mountain Partners, L.P., a Delaware limited partnership (the “ Stockholder ”), and National Medical Health Card Systems, Inc., a Delaware corporation (the “ Company ”).

          WHEREAS, concurrently with the execution of this Agreement, Parent, SXC Health Solutions, Inc., a Texas corporation (“ US Corp. ”), Comet Merger Corporation, a newly-formed Delaware corporation that is wholly-owned by US Corp. and an indirect wholly-owned subsidiary of Parent (“ Merger Sub ”), and the Company are entering into an Agreement and Plan of Merger, dated as of the date hereof (as amended, supplemented, restated or otherwise modified from time to time, the “ Merger Agreement ”) pursuant to which, among other things, Merger Sub will commence an exchange offer (the “ Offer ”) to acquire all of the outstanding shares of common stock, par value $0.001 per share, of the Company (“ Company Common Stock ”), and following the consummation of the Offer (or, subject to certain conditions, in lieu thereof), Merger Sub will merge with and into the Company (the “ Merger ”) and each outstanding share of Company Common Stock and each outstanding share, if any, of the Company’s Series A 7% Convertible Preferred Stock, par value $0.10 per share (“ Company Convertible Preferred Stock ”, and together with the Company Common Stock, “ Company Stock ”), will be converted into the right to receive the merger consideration specified therein.

          WHEREAS, as of the date hereof, the Stockholder is the record and beneficial owner, in the aggregate, of 6,790,797 outstanding shares of the Company Convertible Preferred Stock;

          WHEREAS, as a material inducement to Parent entering into the Merger Agreement, Parent has required that the Stockholder agree, and the Stockholder has agreed, to enter into this agreement and abide by the covenants and obligations with respect to the Covered Shares (as hereinafter defined) set forth herein.

          NOW THEREFORE, in consideration of the foregoing and the mutual representations, warranties, covenants and agreements herein contained, and intending to be legally bound hereby, the parties hereto agree as follows:

ARTICLE I

GENERAL

     1.1. Defined Terms . The following capitalized terms, as used in this Agreement, shall have the meanings set forth below. Capitalized terms used but not otherwise defined herein shall have the meanings ascribed thereto in the Merger Agreement.

          “ Beneficial Ownership ” by a Person of any securities includes ownership by any Person who, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares (i) voting power which includes the power to vote, or to direct the voting of, such security; and/or (ii) investment power which includes the power to dispose, or to direct the disposition, of such security; and shall otherwise be interpreted in accordance with the term “beneficial ownership” as defined in Rule 13d-3 adopted by the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended; provided that for purposes of determining Beneficial Ownership, a Person shall be deemed to be the Beneficial Owner of any securities which such Person has, at any time during the term of this Agreement, the right to acquire pursuant to any agreement, arrangement or understanding or upon the exercise of conversion rights, exchange rights, warrants or options, or otherwise (irrespective of whether the right to acquire such securities is exercisable immediately or only after the passage of time, including the passage of time in excess of 60 days, the satisfaction of any conditions, the occurrence of any event or any combination of the foregoing). The terms “ Beneficially Own ” and “ Beneficially Owned ” shall have a correlative meaning.

          “ Covered Shares ” means, with respect to the Stockholder, the Stockholder’s Existing Shares, together with any shares of Company Stock or other voting capital stock of the Company and any securities convertible into or exercisable or exchangeable for shares of Company Stock or other voting capital stock of the Company, in each case, that the Stockholder acquires Beneficial Ownership of on or after the date hereof.

          “ Encumbrance ” means any security interest, pledge, mortgage, lien (statutory or other), charge, option to purchase, lease or other right to acquire any interest or any claim, restriction, covenant, title defect, hypothecation, assignment, deposit arrangement or other encumbrance of any kind or any preference, priority or other security agreement or preferential arrangement of any kind or nature whatsoever (including any conditional sale or other title retention agreement), excluding restrictions under securities laws and excluding any Encumbrance set forth in the Certificate of Designations.

          “ Existing Shares ” means, with respect to the Stockholder, the number of shares of Company Stock Beneficially Owned and owned of record by the Stockholder, as set forth in the recitals.

          “ Operative Date ” means the Acceptance Date, if the transactions contemplated by the Merger Agreement are effected by means of the Offer followed by the Second Step Merger, and means the Closing, if the transactions contemplated by the Merger Agreement are effected as a One Step Merger.

          “ Other Stockholder ” means New Mountain Affiliated Investors, L.P., a Delaware limited partnership and the holder of the outstanding shares of Company Convertible Preferred Stock not held by the Stockholder.

          “ Transfer ” means, directly or indirectly, to sell, transfer, assign, pledge, encumber, hypothecate or similarly dispose of (by merger (including by conversion into securities or other consideration), by tendering into any tender or exchange offer, by operation of law or otherwise), either voluntarily or involuntarily, or to enter into any contract, option or other

arrangement or understanding with respect to the voting of or sale, transfer, assignment, pledge, encumbrance, hypothecation or similar disposition of (by merger, by tendering into any tender or exchange offer, by operation of law or otherwise) (but does not include any conversion of the Company Convertible Preferred Stock into Company Common Stock after the Certificate of Amendment has become effective).

ARTICLE II

TENDERING

     2.1. Agreement to Tender .

          (a) The Stockholder hereby agrees that, within five business days after commencement of the Offer, the Stockholder shall validly tender or cause to be tendered in the Offer all of the shares of Company Stock represented by the Stockholder’s Covered Shares pursuant to and in accordance with the terms of the Offer, by delivering to the depositary designated in the Offer (the “ Depositary ”) (i) an executed letter of transmittal with respect to the Covered Shares, (ii) a certificate or certificates representing the Covered Shares, (iii) all other documents or instruments required to be delivered pursuant to the terms of the Offer, and (iv) a letter of instruction signed by the Stockholder instructing the Company to convert the Covered Shares into Company Common Stock effective upon receipt of a certificate from an executive officer of Parent stating that (1) all of the conditions to the Offer (other than the Minimum Condition) have been satisfied or waived, (2) upon the conversion by the Stockholder of its Covered Shares into Company Common Stock and the conversion by the Other Stockholder of the shares of Company Stock owned by it into Company Common Stock, the Minimum Condition will have been satisfied, and (3) Merger Sub stands ready to, and will, immediately following such conversion by the Stockholder and the Other Stockholder, accept for payment all shares of Company Common Stock validly tendered in the Offer and not theretofore withdrawn (all of the foregoing documents, the “ Tender Documents ”).

          (b) The Stockholder hereby agrees that once the Tender Documents shall have been delivered to the Depositary, the Stockholder will not withdraw, nor permit the withdrawal of, any Tender Documents from the Offer, unless and until (i) the Offer shall have been terminated by Merger Sub in accordance with the terms of the Merger Agreement, or (ii) this Agreement shall have been terminated in accordance with Section 6.1.

          (c) Notwithstanding the provisions of Sections 2.1(a) and 2.1(b), in the event of a Change in Recommendation made in compliance with the Merger Agreement, the obligation of the Stockholder to tender and not withdraw its Covered Shares in the manner set forth in this Section 2.1 shall only apply to an aggregate number of Covered Shares that is equal to 30% of the total number of shares of Company Stock outstanding on the Acceptance Date, and the Stockholder may or may not tender the balance of its Covered Shares in the Offer, and may withdraw from the Offer all or any portion of such balance of its Covered Shares that it may previously have tendered, as the Stockholder, in its sole discretion, determines.

ARTICLE III

VOTING

     3.1. Agreement to Vote .

          (a) The Stockholder hereby irrevocably and unconditionally agrees that during the period beginning on the date hereof and ending on the earliest of (x) the Operative Date, (y) the termination of the Merger Agreement in accordance with its terms or (z) the termination of this Agreement in accordance with its terms, at the Company Stockholders Meeting and at any other meeting of the stockholders of the Company, however called, including any adjournment or postponement thereof, and in connection with any written consent of the stockholders of the Company, the Stockholder shall, in each case, to the fullest extent that such matters are submitted for the vote or written consent of the Stockholder and that the Covered Shares are entitled to vote thereon or consent thereto:

          (i) appear at each such meeting or otherwise cause the Covered Shares as to which the Stockholder controls the right to vote to be counted as present thereat for purposes of calculating a quorum; and

          (ii) vote (or cause to be voted), in person or by proxy, or deliver (or cause to be delivered) a written consent covering, all of the Covered Shares as to which the Stockholder controls the right to vote (or, if applicable, only such portion of the Covered Shares as is provided in Section 3.1(b)) (i) in favor of the adoption of the Merger Agreement and any related proposal in furtherance thereof, as reasonably requested by Parent, submitted for the vote or written consent of stockholders; (ii) against any action or agreement submitted for the vote or written consent of stockholders that the Stockholder knows is in opposition to, or competitive or materially inconsistent with, the Offer or the Merger or that the Stockholder knows would result in a breach of any covenant, representation or warranty or any other obligation or agreement of the Company contained in the Merger Agreement, or of the Stockholder contained in this Agreement; and (iii) against any Acquisition Proposal and against any other action, agreement or transaction submitted for the vote or written consent of stockholders that the Stockholder knows would impede, interfere with, delay, postpone, discourage, frustrate the purposes of or adversely affect the Offer, the Merger or the other transactions contemplated by the Merger Agreement or this Agreement or the performance by the Company of its obligations under the Merger Agreement or by the Stockholder of its obligations under this Agreement, including, but not limited to: (A) any extraordinary corporate transaction, such as a merger, consolidation or other business combination involving the Company or any subsidiary of the Company; (B) any sale, lease or transfer of a material amount of assets of the Company (including capital stock or other equity interest in its Subsidiaries) or any subsidiary of the Company; (C) any reorganization, recapitalization, dissolution or liquidation of the Company or any subsidiary of the Company; (D) any change in a majority of the board of directors of the Company; (E) any amendment to the Company’s certificate of incorporation or bylaws (except for any amendment to increase the authorized capital stock); and (F) any change in the capitalization of the Company or the Company’s corporate structure.

The obligations of the Stockholder specified in this Section 3.1(a) shall apply whether or not the Offer, the Merger or any action described above is recommended by the Board of Directors of the Company. Any such vote shall be cast (or consent shall be given) by the Stockholder in accordance with such procedures relating thereto so as to ensure that it is duly counted, including for purposes of determining whether a quorum is present.

          (b) Notwithstanding the provisions of Section 3.1(a), in the event of a Change in Recommendation made in compliance with the Merger Agreement, the obligation of the Stockholder to vote (or cause to be voted), or to deliver (or cause to be delivered) a written consent with respect to, the Covered Shares in the manner set forth in this Section 3.1 shall, with respect to any combined vote of holders of Company Common Stock and Company Convertible Preferred Stock, only apply to an aggregate number of Covered Shares entitled to vote in respect of such matter that is equal to 30% of the total vote of the shares of Company Stock entitled to vote in respect of such matter, and shall terminate, together with the authority of each of the proxies set forth in Section 3.3, with respect to the balance of the Covered Shares, and the Stockholder may vote (or cause to be voted), or deliver (or cause to be delivered) a written consent with respect to, such balance of its Covered Shares as the Stockholder, in its sole discretion, determines.

     3.2. No Inconsistent Agreements . The Stockholder hereby covenants and agrees that, except for this Agreement or as set forth in Section 7 of the Certificate of Designations, and except as may be permitted by Section 5.4(b), it (a) has not entered into, and shall not enter into at any time while this Agreement remains in effect, any voting agreement or voting trust with respect to the Covered Shares with respect to any of the matters described in Section 3.1(a)(ii) (the “ Section 3.1(a) Matters ”), (b) has not granted, and shall not grant at any time while this Agreement remains in effect (except pursuant to Section 3.3), a proxy, consent or power of attorney with respect to the Covered Shares with respect to any of the Section 3.1(a) Matters and (c) has not knowingly taken and shall not knowingly take any action that would make any representation or warranty of the Stockholder contained herein untrue or incorrect or have the effect of preventing or disabling the Stockholder from performing any of its obligations under this Agreement.

     3.3. Proxy . Without in any way limiting the Stockholder’s right to vote the Covered Shares in its sole discretion on any matters other than the Section 3.1(a) Matters that may be submitted to a stockholder vote, consent or other approval, the Stockholder hereby irrevocably appoints as its proxy and attorney-in-fact, Gordon Glenn and Jeffrey Park, pursuant to a proxy to be delivered to Parent substantially in the form attached hereto as Annex A, in their respective capacities as officers of Parent, and any individual who shall hereafter succeed to any such officer of Parent, and any other Person designated in writing by Parent (collectively, the “ Grantees ”), each of them individually, with full power of substitution, to vote or execute written consents with respect to the Covered Shares as to which the Stockholder controls the right to vote in accordance with Section 3.1 (or, if applicable, only such portion of the Covered Shares as is provided in Section 3.1(b)) and, in the discretion of the Grantees, with respect to any proposed postponements or adjournments of any annual or special meeting of the stockholders of the Company at which any of the Section 3.1(a) Matters was to be considered. This proxy is coupled with an interest and shall be irrevocable until the earliest of (i) the Operative Date, (ii) the termination of the Merger Agreement in accordance with its terms, or (iii) the termination of

this Agreement in accordance with its terms, in which event this proxy shall automatically be revoked without any further action by any party. The Stockholder will take such further action or execute such other instruments as may be necessary to effectuate the intent of this proxy and hereby revokes any proxy previously granted by it with respect to the Covered Shares with respect to any of the Section 3.1(a) Matters. So long as the proxy granted under this Section 3.3 is a valid uncontested proxy that is effective to deliver the votes of the Covered Shares (or, if applicable, only such portion of the Covered Shares as is provided in Section 3.1(b)), the Stockholder shall be deemed to be fulfilling its obligations under Section 3.1. If Parent believes that such proxy is not a valid proxy or if Parent otherwise does not wish to utilize the proxy, Parent will so notify the Stockholder in writing so that the Stockholder will be able to perform its obligations under Section 3.1.

ARTICLE IV

REPRESENTATIONS AND WARRANTIES

     4.1. Representations and Warranties of the Stockholder . The Stockholder hereby represents and warrants to Parent as follows:

          (a) Organization; Authorization; Validity of Agreement; Necessary Action . The Stockholder is duly organized and is validly existing and in good standing under the laws of the jurisdiction of its formation. The Stockholder has full power and authority to execute and deliver this Agreement, to perform its obligations hereunder and to consummate the transactions contemplated hereby. The execution and delivery by the Stockholder of this Agreement, the performance by it of its obligations hereunder and the consummation by it of the transactions contemplated hereby have been duly and validly authorized by the Stockholder and no other actions or proceedings on the part of the Stockholder or any stockholder thereof are necessary to authorize the execution and delivery by it of this Agreement, the performance by it of its obligations hereunder or the consummation by it of the transactions contemplated hereby. This Agreement has been duly executed and delivered by the Stockholder and, assuming this Agreement constitutes a valid and binding obligation of the other parties hereto, constitutes a legal, valid and binding obligation of the Stockholder, enforceable against it in accordance with its terms, subject to bankruptcy, insolvency, fraudulent transfer, moratorium, reorganization or similar laws affecting the rights of creditors generally and the availability of equitable remedies (regardless of whether such enforceability is considered in a proceeding in equity or at law).

          (b) Ownership . The Stockholder’s Existing Shares are, and all of the Covered Shares owned by the Stockholder from the date hereof through and on the Operative Date will be, Beneficially Owned and owned of record by the Stockholder, except that, in the case of the Offer, the Company Convertible Preferred Stock will have been converted into Company Common Stock in accordance with the terms of this Agreement. The Stockholder has good and marketable title to the Stockholder’s Existing Shares, free and clear of any Encumbrances. As of the date hereof, the Stockholder’s Existing Shares constitute all of the shares of Company Stock Beneficially Owned or owned of record by the Stockholder. Except for the rights granted to Parent hereby, the Stockholder has and will have at all times through the Operative Date sole voting power (including the right to control such vote as contemplated herein) with respect to the Section 3.1(a) Matters, sole power of disposition, sole power to issue instructions with respect to

the Section 3.1(a) Matters, and sole power to agree to all of the matters set forth in this Agreement, in each case, with respect to all of the Stockholder’s Existing Shares and with respect to all of the Covered Shares owned by the Stockholder at all times through the Operative Date.

          (c) No Violation . The execution, delivery and performance of this Agreement by the Stockholder does not and will not (whether with or without notice or lapse of time, or both) (i) violate any provision of the certificate of formation or bylaws or other comparable governing documents, as applicable, of the Stockholder, (ii) violate, conflict with or result in the breach of any of the terms or conditions of, result in any (or the right to make any) modification of or the cancellation or loss of a benefit under, require any notice, consent or action under, or otherwise give any Person the right to terminate, accelerate obligations under or receive payment or additional rights under, or constitute a default under, any Contract to which the Stockholder is a party or by which it is bound or (iii) violate any Law applicable to the Stockholder or by which any of the Stockholder’s assets or properties is bound, except for any of the foregoing as would not, either individually or in the aggregate, impair the ability of the Stockholder to perform its obligations hereunder or to consummate the transactions contemplated hereby on a timely basis.

          (d) Consents and Approvals . Other than compliance with applicable securities laws and Laws relating to competition (including any filing under the HSR Act), the execution and delivery of this Agreement by the Stockholder does not, and the performance by the Stockholder of its obligations under this Agreement and the consummation by it of the transactions contemplated hereby will not, require the Stockholder to obtain any consent, approval, authorization or permit of, or to make any filing with or notification to, any Governmental Entity, except where the failure to obtain such consents, approvals, authorizations or permits, or to make such filings or notifications, would not, either individually or in the aggregate, prevent or delay the performance by the Stockholder of any of its obligations under this Agreement.

          (e) Absence of Litigation . As of the date hereof, there is no Action pending or, to the knowledge of the Stockholder, threatened against the Stockholder or any of its Affiliates before or by any Governmental Entity that would impair the ability of the Stockholder to perform its obligations hereunder or to consummate the transactions contemplated hereby on a timely basis.

          (f) Finder’s Fees . Except as disclosed pursuant to the Merger Agreement, no investment banker, broker, finder or other intermediary is entitled to a fee or commission from Parent, US Corp., Merger Sub or the Company in respect of this Agreement based upon any arrangement or agreement made by or at the direction of the Stockholder.

          (g) Reliance by Parent, US Corp. and Merger Sub . The Stockholder understands and acknowledges that Parent, US Corp. and Merger Sub are entering into the Merger Agreement in reliance upon the Stockholder’s execution and delivery of this Agreement and the representations and warranties of the Stockholder contained herein.

ARTICLE V

OTHER COVENANTS

     5.1. Prohibition on Transfers, Other Actions .

          (a) Except as permitted by Section 5.4(b), the Stockholder hereby agrees not to (i) Transfer any of the Covered Shares, Beneficial Ownership thereof or any other interest specifically therein (including by tendering into another tender or exchange offer), except to participate in the Offer or the Merger; (ii) enter into any agreement, arrangement or understanding with any Person (other than Parent, US Corp. or Merger Sub), or knowingly take any other action, that violates or conflicts with the Stockholder’s representations, warranties, covenants and obligations under this Agreement; or (iii) knowingly take any action that could restrict or otherwise affect the Stockholder’s legal power, authority and right to comply with and perform its covenants and obligations under this Agreement. Any Transfer in violation of this provision shall be void.

          (b) The Stockholder hereby covenants and agrees that for a period of one year following the Operative Date (the “ Lock-Up Period ”), the Stockholder shall not Transfer, or consent to any Transfer of, any shares of Parent Common Stock, or any interest therein, or enter into any Contract, option or other arrangement (including any profit sharing or other derivative arrangement) with respect to the Transfer of, any shares of Parent Common Stock or any interest therein to any person; provided that the Stockholder may participate during the Lock-Up Period with respect to its shares of Parent Common Stock in any merger, tender offer or other business combination or other transaction, in each case, which the Board of Directors of Parent has recommended to Parent’s stockholders. The Stockholder hereby agrees that, in order to ensure compliance with the restrictions referred to herein, Parent may issue appropriate “stop transfer” instructions to its transfer agent in respect of the Stockholder’s Parent Common Stock. Parent agrees that it will cause any stop transfer instructions imposed pursuant to this Section 5.1(b) to be lifted, and any legended certificates of Parent Common Stock delivered to the Stockholder pursuant to the Merger Agreement to be replaced with certificates not bearing such legend, promptly following the termination of the Lock-Up Period. The restrictions on transfer provided in this Section 5.1(b) shall be in addition to