SXCI Catamaran Corporation (MM)

SUMMARY

The following is a summary that highlights information contained in this joint proxy statement/prospectus. This summary does not contain all of the information that might be important to you. For a more complete description of the merger agreement and the transactions contemplated by the merger agreement, including the merger and the issuance of shares of SXC common stock pursuant to the merger agreement, we encourage you to read carefully this entire joint proxy statement/prospectus, including the attached Annexes. In addition, we encourage you to read carefully the information incorporated by reference into this joint proxy statement/prospectus, which includes important business and financial information about SXC and Catalyst that has been filed with the SEC, and in the case of SXC, also filed with SEDAR. You may obtain the information incorporated by reference into this joint proxy statement/prospectus without charge by following the instructions in the section entitled “Additional Information—Where You Can Find More Information” beginning on page 233.

Information About the Companies

SXC Health Solutions Corp.

2441 Warrenville Road

Suite 610

Lisle, Illinois 60532-3642

(800) 282-3232

SXC Health Solutions Corp. is a leading provider of pharmacy benefit management, which we refer to as PBM, services and healthcare information technology, which we refer to as HCIT, solutions to the healthcare benefit management industry. SXC’s product offerings and solutions combine a wide range of applications and PBM services designed to assist SXC’s customers in reducing the cost and managing the complexity of their prescription drug programs.

SXC’s customers include many of the largest organizations in the pharmaceutical supply chain, such as pharmacy benefit managers, managed care organizations, self-insured employer groups, unions, third party health care plan administrators, and state and federal government entities.

SXC conducts business in both the United States and Canada. SXC common stock is traded on NASDAQ under the symbol “SXCI” and the Toronto Stock Exchange under the symbol “SXC”.

SXC Health Solutions, Inc.

2441 Warrenville Road

Suite 610

Lisle, Illinois 60532-3642

(800) 282-3232

SXC Health Solutions, Inc., which we refer to as US Corp., is a direct wholly-owned subsidiary of SXC.

Catamaran I Corp.

2441 Warrenville Road

Suite 610

Lisle, Illinois 60532-3642

(800) 282-3232

Catamaran I Corp., which we refer to as Merger Sub, is a direct wholly-owned subsidiary of US Corp. and was formed solely for the purpose of consummating the merger and the subsequent merger. Merger Sub has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the transactions.

Catamaran II LLC

2441 Warrenville Road

Suite 610

Lisle, Illinois 60532-3642

(800) 282-3232

Catamaran II LLC, which we refer to as Merger LLC, is a direct wholly-owned subsidiary of US Corp. and was formed solely for the purpose of consummating the subsequent merger. Merger LLC has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the transactions.

Catalyst Health Solutions, Inc.

800 King Farm Boulevard

Rockville, Maryland 20850

(301) 548-2900

Catalyst Health Solutions is a full-service PBM company that primarily operates under the brand name “Catalyst Rx.” Catalyst is built on strong, innovative principles in the management of prescription drug benefits and has a client-centered philosophy. Catalyst clients include self-insured employers, state and local governments, managed care organizations, which we refer to as MCOs, unions, third-party administrators, which we refer to as TPAs, hospices and individuals who contract with Catalyst to administer the prescription drug component of their overall health benefit programs.

Catalyst provides clients access to a contracted, non-exclusive national network of approximately 65,000 pharmacies. Catalyst’s primary business is to provide its clients and their members with timely and accurate benefit adjudication, while controlling pharmacy spending trends through customized plan designs, clinical programs, physician orientation programs, and member education. Catalyst uses electronic point-of-sale system of eligibility verification and plan design information, and offers access to rebate arrangements for certain branded pharmaceuticals.

Catalyst was incorporated in Delaware in 1999 and Catalyst common stock trades on NASDAQ under the symbol “CHSI”.

The Merger (see page 51)

SXC and Catalyst have agreed to a business combination under the terms and conditions set forth in the merger agreement, which we describe in this joint proxy statement/prospectus. Pursuant to the merger agreement, Merger Sub will merge with and into Catalyst, with Catalyst continuing as the surviving corporation and as a wholly-owned subsidiary of US Corp., a wholly-owned subsidiary of SXC. We refer to this as the merger. Immediately following the effective time of the merger, provided that certain tax opinions are received by Catalyst and SXC, Catalyst, as the surviving corporation from the merger, will merge with and into Merger LLC, with Merger LLC surviving the second merger. We refer to this as the subsequent merger. We refer to the merger and the subsequent merger collectively as the transactions. It is intended that the subsequent merger, if it occurs, will be effected immediately after the effective time of the merger. We have attached the merger agreement as Annex A to this joint proxy statement/prospectus. We encourage you to carefully read the merger agreement in its entirety. We currently expect that the merger will be completed during the second half of 2012, subject to the satisfaction or waiver of the conditions to the merger. However, we cannot predict the actual timing of the completion of the merger.

Merger Consideration (see page 121)

The merger agreement provides that at the effective time, each share of Catalyst common stock issued and outstanding immediately prior to the effective time (other than shares of Catalyst common stock held by Catalyst, SXC, US Corp., Merger Sub, Merger LLC or any of their wholly-owned subsidiaries and shares of Catalyst with respect to which appraisal rights are validly exercised) will be converted into the right to receive the combination of (x) $28.00 in cash without interest, which we refer to as the per share cash amount, and (y) 0.6606 of a validly issued, fully paid and nonassessable share of SXC common stock, which we refer to as the exchange ratio. We refer to the shares of SXC common stock to be issued to holders of Catalyst common stock, when combined with the per share cash amount, as the merger consideration.

The exchange ratio and the per share cash amount will not change from what was agreed to in the merger agreement (other than for adjustment in the event that there is any change prior to the effective time in the outstanding shares of capital stock of SXC or Catalyst as a result of any reclassification, stock split (including a reverse stock split), recapitalization, split-up, combination, exchange or readjustment of shares, or any stock dividend). However, since the market price of SXC common stock will fluctuate, the total value of the stock portion of the merger consideration and therefore the value of the total merger consideration may increase or decrease between the date of the merger agreement and the effective time.

Accordingly, the value of the actual per share consideration to be paid to Catalyst stockholders cannot be determined until after the effective time.

Treatment of Equity Awards in the Merger (see page 121)

Treatment of Stock Options

Under the merger agreement, each option to purchase Catalyst common stock granted under a Catalyst stock plan that is outstanding immediately prior to the effective time will, to the extent permitted by the terms of the applicable plan, be assumed by SXC and become an option to purchase SXC common stock, on the same terms and conditions as the Catalyst stock option (but taking into account any changes to the option, including any acceleration, lapse or other vesting, provided in the Catalyst stock plan or related award documents by reason of the merger).

The number of shares of SXC common stock subject to each such converted stock option will be equal to the number of shares of Catalyst common stock subject to such Catalyst stock option, multiplied by the option exchange ratio, rounded down to the nearest whole share of SXC common stock. The exercise price per share for each such converted stock option will be equal to the per share exercise price specified in such Catalyst stock option divided by the option exchange ratio (rounded up to the nearest cent).

The “option exchange ratio” is equal to the sum of 0.6606 plus the fraction obtained by dividing $28.00 by the average per share last reported sale price of SXC common stock on NASDAQ over the five trading days preceding the closing date of the merger.

Treatment of Restricted Stock

At the effective time, each outstanding share of restricted stock granted under a Catalyst stock plan will become fully vested and will be cancelled in exchange for the right to receive the merger consideration as described in “The Merger Agreement—Merger Consideration” beginning on page 121.

Treatment of Performance Share Unit Awards

Under the merger agreement, each award of performance share units with respect to shares of Catalyst common stock granted under a Catalyst stock plan that is outstanding immediately prior to the effective time will become fully vested at 100% of the target number of performance share units subject to such performance share unit award. Such performance share unit awards will be cancelled in exchange for the right to receive the merger consideration as described in “The Merger Agreement—Merger Consideration” beginning on page 121.

Treatment of Warrants

Under the merger agreement, certain unexpired and unexercised Catalyst warrants issued pursuant to a stock purchase agreement, dated as of June 18, 2004, which we refer to as the 2008 warrants, will be assumed by SXC and become a warrant to purchase the number of shares of SXC common stock (decreased to the nearest full share) determined by multiplying (i) the number of shares of Catalyst common stock subject to the 2008 warrant immediately prior to the effective time by (ii) the option exchange ratio, at an exercise price per share of SXC common stock (rounded up to the nearest cent) equal to the exercise price per share of Catalyst common stock under the 2008 warrant immediately prior to the effective time divided by the option exchange ratio. We refer to such assumed 2008 warrants as the new SXC warrants.

Under the merger agreement, certain unexpired and unexercised Catalyst warrants issued pursuant to a stock purchase agreement, dated as of August 25, 2010, which we refer to as the 2010 warrants, will be cancelled and converted into the right to receive, upon payment of the aggregate exercise price of the 2010 warrant, the combination of (x) the product of the per share cash amount (without interest, and subject to deduction for any required withholding taxes), multiplied by the number of shares of the Catalyst common stock subject to the 2010 warrant as of immediately prior to the effective time, and (y) the number of shares of SXC common stock (decreased to the nearest full share) equal to the product of the exchange ratio, multiplied by the number of shares of Catalyst common stock subject to the 2010 warrant immediately prior to the effective time.

Ownership of SXC After the Merger

Based on the number of shares of common stock of SXC and Catalyst outstanding on May 31, 2012, the record date for the two companies’ special meetings, SXC expects to issue or reserve for issuance approximately 34 million shares of SXC common stock in connection with the merger (including shares of SXC common stock issuable to Catalyst stockholders and shares issuable pursuant to Catalyst warrants and Catalyst stock options and other equity-based awards). Based on these numbers, upon the completion of the merger, SXC shareholders and former Catalyst stockholders would own approximately 67% and 33% of the outstanding shares of SXC common stock, respectively, immediately following the completion of the merger. The merger will have no effect on the number of shares of SXC common stock owned by existing SXC shareholders.

Share Ownership of Directors and Executive Officers

At the close of business on the SXC record date, directors and executive officers of SXC and their affiliates owned and were entitled to vote approximately 334,624 shares of SXC common stock, collectively representing approximately 0.4% of the shares of SXC common stock outstanding on that date.

At the close of business on the Catalyst record date, directors and executive officers of Catalyst and their affiliates owned and were entitled to vote approximately 736,344 shares of Catalyst common stock, collectively representing 1.5% of the shares of Catalyst common stock outstanding on that date.

Recommendation of the SXC Board of Directors and Its Reasons for the Merger (see page 59)

After careful consideration, on April 17, 2012 the SXC board of directors unanimously approved the merger agreement and the consummation of the transactions contemplated by the merger agreement, including the merger and the share issuance, upon the terms and subject to the conditions set forth in the merger agreement. The SXC board of directors has unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement, including the issuance of shares of SXC common stock pursuant to the merger agreement, are advisable, fair to and in the best interest of SXC and its shareholders and unanimously recommends that SXC shareholders vote “FOR” the proposal to approve the issuance of shares of SXC common stock pursuant to the merger agreement and “FOR” the SXC meeting adjournment proposal at the SXC special meeting.

For a summary of the factors considered by the SXC board of directors in reaching its decision to approve the merger agreement as well as the SXC board of directors’ reasons for, and certain risks related to, the merger, see “The Merger—Recommendation of the SXC Board of Directors and Its Reasons for the Merger” beginning on page 59.

Recommendation of the Catalyst Board of Directors and Its Reasons for the Merger (see page 64)

After careful consideration, on April 17, 2012, the Catalyst board of directors unanimously approved the merger agreement and the consummation of the transactions contemplated by the merger agreement, including the merger, upon the terms and subject to the conditions set forth in the merger agreement. The Catalyst board of directors has unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are advisable, fair to and in the best interest of Catalyst and its stockholders and unanimously recommends that Catalyst’s stockholders vote “FOR” the proposal to adopt the merger agreement, “FOR” the Catalyst compensation arrangements proposal and “FOR” the Catalyst meeting adjournment proposal at the Catalyst special meeting.

For a summary of the factors considered by the Catalyst board of directors in reaching its decision to adopt the merger agreement and approve the consummation of the transactions contemplated by the merger agreement, including the merger, as well as the Catalyst board of directors’ reasons for, and certain risks related to, the merger, see “The Merger—Recommendation of the Catalyst Board of Directors and Its Reasons for the Merger” beginning on page 64.

Opinions of Financial Advisors (see page 71)

Opinions of SXC’s Financial Advisors

Barclays Opinion

Barclays Capital Inc., which we refer to as Barclays, delivered its written opinion to the SXC board of directors that, as of April 17, 2012, and based upon and subject to the factors, procedures, assumptions, qualifications and limitations set forth therein, the consideration to be paid by SXC in the proposed merger was fair, from a financial point of view, to SXC.

The full text of Barclays’ written opinion, dated as of April 17, 2012, is attached as Annex B to this joint proxy statement/prospectus. Barclays’ written opinion sets forth, among other things, the assumptions made, procedures followed, factors considered and limitations upon the review undertaken by Barclays in rendering its opinion. SXC’s shareholders are encouraged to read the opinion carefully in its entirety. The summary of Barclays’ opinion and the methodology that Barclays used to render its opinion in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinion.

J.P. Morgan Opinion

J.P. Morgan Securities LLC, which we refer to as J.P. Morgan, delivered its written opinion to the SXC board of directors that, as of April 17, 2012, and based upon and subject to the factors, procedures, assumptions, qualifications and limitations set forth therein, the consideration to be paid by SXC in the proposed merger was fair, from a financial point of view, to SXC.

The full text of the written opinion of J.P. Morgan, dated April 17, 2012, which sets forth, among other things, the assumptions made, procedures followed, matters considered and qualifications and limitations on the review undertaken in connection with its opinion, is attached as Annex C to this joint proxy statement/prospectus and is incorporated herein by reference. SXC’s shareholders are urged to read the opinion in its entirety. J.P. Morgan’s written opinion is addressed to the SXC board of directors and is directed only to the consideration to be paid in the proposed merger and does not constitute a recommendation to any SXC shareholder or Catalyst stockholder as to how they should vote at the special meeting. The summary of the opinion of J.P. Morgan set forth in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of such opinion.

Opinion of Catalyst’s Financial Advisor

On April 17, 2012, at a meeting of the Catalyst board of directors, Goldman Sachs & Co., which we refer to as Goldman Sachs, rendered to the Catalyst board of directors its oral opinion, subsequently confirmed in writing, that, as of April 17, 2012 and based upon and subject to the limitations and assumptions set forth therein, the per share consideration of $28.00 in cash and 0.6606 shares of SXC common stock, collectively, “the merger consideration”, to be paid to the holders (other than SXC and its affiliates) of Catalyst common stock pursuant to the merger agreement was fair from a financial point of view to those holders.

The full text of the written opinion of Goldman Sachs, dated April 17, 2012, which sets forth the assumptions made, procedures followed, matters considered, qualifications and limitations on the review undertaken in connection with the opinion, is attached as Annex D to this joint proxy statement/prospectus. The summary of the Goldman Sachs opinion provided in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of the written opinion. Goldman Sachs’ advisory services and opinion were provided for the information and assistance of the Catalyst board of directors in connection with its consideration of the proposed merger and the opinion does not constitute a recommendation as to how any holder of Catalyst common stock should vote with respect to the proposed merger or any other matter.

Interests of Catalyst’s Directors and Executive Officers in the Merger (see page 112)

The directors and executive officers of Catalyst have interests in the merger that are in addition to their interests as stockholders of Catalyst generally. The Catalyst board of directors was aware of these interests and considered them, among other matters, in approving the merger and in determining to recommend that Catalyst stockholders adopt the merger agreement. See “The Merger—Interests of Catalyst’s Directors and Executive Officers in the Merger,” beginning on page 112 for additional information about these interests.

Board of Directors of SXC After the Merger (see page 112)

In connection with the merger, SXC has agreed to appoint two designees mutually agreed upon by SXC and Catalyst to the SXC board of directors. As of the date of this joint proxy statement/prospectus, no determination has been made as to the identity of the mutual designees who will be appointed to the SXC board of directors. The two designees to be appointed to the SXC board of directors will be compensated in the same manner and

amounts as other non-employee directors of SXC. See “SXC Executive Compensation—Compensation of Directors.”

Information about the current SXC directors and executive officers can be found in the documents listed under the heading “Additional Information—Where You Can Find More Information” beginning on page 233.

Listing of SXC Common Stock (see page 108) and Delisting and Deregistration of Catalyst Common Stock (see page 111)

Application will be made to have the shares of SXC common stock to be issued in the merger approved for listing on NASDAQ and on the Toronto Stock Exchange, which we refer to as the TSX, where SXC common stock currently is traded under the symbols “SXCI” and “SXC,” respectively. If the merger is completed, Catalyst common stock will be delisted from NASDAQ and will be deregistered under the Securities Exchange Act of 1934, as amended, which we refer to as the Exchange Act, and Catalyst will no longer file periodic reports with the SEC.

Catalyst Stockholder Appraisal Rights (see page 108)

Under Delaware law, Catalyst stockholders of record who do not vote in favor of the proposal to adopt the merger agreement will be entitled to seek appraisal rights and obtain payment in cash for the judicially determined fair value of their shares of Catalyst common stock in connection with the merger, if the merger is completed. This value could be more than, less than or the same as the implied value of the merger consideration for Catalyst common stock. The relevant provisions of the General Corporation Law of the State of Delaware, which we refer to as the DGCL, are included as Annex E to this joint proxy statement/prospectus. We encourage you to read these provisions carefully and in their entirety. Moreover, due to the complexity of the procedures for exercising the right to seek appraisal, Catalyst stockholders who are considering exercising such rights are encouraged to seek the advice of legal counsel. Failure to strictly comply with these provisions will result in a loss of the right of appraisal.

Merely not voting for the merger will not preserve the right of Catalyst stockholders to seek an appraisal of their shares of Catalyst common stock under Delaware law because a submitted proxy not marked “against” or “abstain” will be voted “FOR” the proposal to adopt the merger agreement and “FOR” the Catalyst special meeting adjournment proposal. Accordingly, the submission of a proxy not marked “against” or “abstain” will result in the waiver of appraisal rights. Catalyst stockholders who wish to exercise their appraisal rights and hold shares in the name of a broker or other nominee must instruct their nominees to take the steps necessary to enable them to demand appraisal for their shares.

Conditions to Completion of the Merger (see page 124)

A number of conditions to each party’s obligation to complete the merger must be satisfied before the merger will be completed, including:

In addition, it is a condition to SXC’s obligation to close that no more than 10% of the outstanding shares of Catalyst common stock elect to exercise appraisal rights as of the completion of the merger in accordance with the terms of the merger agreement.

Some of the conditions set forth in the merger agreement may be waived by SXC or Catalyst, subject to the agreement of the other party in specific cases. For a more detailed discussion of these matters, see “The Merger Agreement—Conditions to Completion of the Merger” beginning on page 124.

Regulatory Approvals (see page 94)

SXC and Catalyst have agreed to use their commercially reasonable efforts to obtain all regulatory approvals required to complete the transactions contemplated by the merger agreement, provided that SXC is not required to agree to any “burdensome regulatory action” (as that term is defined under “The Merger Agreement—Efforts to Complete the Merger” beginning on page 134). These approvals include approvals under, or the expiration or termination of waiting periods pursuant to, the HSR Act and receipt of various state license approvals. On May 29, 2012, at 11:59 p.m. Eastern Daylight Time, the waiting period under the HSR Act expired.

Litigation (see page 95)

On or about April 20, 2012, Hillary Coyne, an alleged Catalyst stockholder, filed a complaint in the Court of Chancery of the State of Delaware against Catalyst, Catalyst’s directors, SXC and certain wholly-owned subsidiaries of SXC (collectively “the defendants”). The complaint purports to be brought on behalf of a class of

all Catalyst stockholders and alleges that the Catalyst directors violated their fiduciary duties, in connection with their negotiation of and agreement to the merger agreement and the merger by, among other things, agreeing to allegedly inadequate consideration and preclusive terms. The SXC defendants are alleged to have aided and abetted the Catalyst directors’ alleged breaches of fiduciary duty. The complaint seeks a preliminary and permanent injunction against the merger and, in the alternative, damages. On April 23, 2012 and April 30, 2012, Colleen Witmer and Ida Lindell, respectively, each alleged Catalyst stockholders, filed complaints in the Court of Chancery of the State of Delaware against the same defendants, alleging substantially the same facts and seeking relief similar to that sought in the Coyne action. On or about April 27, 2012, Susan Edinburgh Schafer, an alleged Catalyst stockholder, filed a fourth complaint in the Circuit Court for Montgomery County, State of Maryland against Catalyst, Catalyst’s directors and SXC alleging substantially the same facts and seeking relief similar to that sought in the Delaware actions. On or about May 8, 2012, Haverhill Retirement System, an alleged Catalyst stockholder, filed a complaint in the Court of Chancery of the State of Delaware against the same defendants, alleging substantially the same facts and seeking relief similar to that sought in the Coyne action, with the addition of allegations of misleading disclosures and omissions in the initial filing with the SEC of the registration statement, of which this joint proxy statement/prospectus forms a part. On or about May 10, 2012, Haverhill filed a motion seeking expedited proceedings. Catalyst and SXC have opposed this motion. On or about May 16, 2012, Haverhill filed an amended complaint and a motion to consolidate the four currently-pending actions in Delaware. On or about May 18, 2012, Lindell filed an amended complaint which, among other things, added allegations of false and misleading disclosures in the initial filing with the SEC of the registration statement, of which this joint proxy statement/prospectus forms a part. The Lindell and Haverhill plaintiffs have filed competing motions for the appointment of lead plaintiff and lead counsel. A hearing was held on May 24, 2012 with the Delaware Court of Chancery. On May 25, 2012, the Delaware Court of Chancery issued a decision and order consolidating the Delaware cases and designating the Haverhill plaintiff’s counsel as lead counsel.

Description of Debt Financing (see page 154)

Concurrently, and in connection with entering into the merger agreement, SXC entered into a debt commitment letter, which we refer to as the debt commitment letter, with JPMorgan Chase Bank, N.A., which we refer to as JPMCB, and J.P. Morgan. JPMCB, J.P. Morgan and SXC subsequently entered into accession agreements to the debt commitment letter, which we refer to as the accession agreements, with Bank of America, N.A., which we refer to as Bank of America, Barclays Bank PLC, which we refer to as Barclays Bank, and SunTrust Bank, which we refer to as SunTrust. Pursuant to the debt commitment letter and the accession agreements and subject to the conditions set forth therein, JPMCB, Bank of America, Barclays Bank and SunTrust committed to provide senior secured credit facilities in an aggregate amount of $1.8 billion, consisting of (i) a five-year senior secured term loan A facility in the amount of $650 million, which we refer to as the term loan A facility, (ii) a seven-year senior secured term loan B facility in the amount of $800 million, which we refer to as the term loan B facility, and (iii) a five-year senior secured revolving credit facility in the amount of $350 million, which we refer to as the revolving facility. The proceeds from the term loan facilities will be used to finance a portion of the cash component of the aggregate merger consideration, repay existing SXC and Catalyst indebtedness and pay related fees and expenses. Borrowings under the revolving facility may be used for general corporate purposes, including financing a portion of the cash component of the aggregate merger consideration, repayment of existing SXC and Catalyst indebtedness, financing permitted acquisitions and payment of related fees and expenses. The term A loan facility and the revolving facility will mature five years following the closing date of the merger and the term B loan facility will mature seven years following the closing date of the merger. The debt commitment letter provides, among other things, that the closings of the term loan facilities and the revolving facility are subject to certain customary conditions.

On May 16, 2012, SXC issued 5,980,000 shares of SXC common stock in an underwritten public offering and received net proceeds of approximately $518.6 million, after underwriting discounts and commissions and estimated offering expenses. SXC expects to use approximately $400 million of these proceeds to finance a portion of the cash component of the aggregate merger consideration, thereby reducing the amount of debt necessary to finance the cash portion of the aggregate merger consideration by an equal amount.

No Solicitation of Alternative Transactions by Catalyst (see page 127)

Subject to certain exceptions, the merger agreement precludes Catalyst from soliciting or engaging in discussions or negotiations with a third party with respect to a proposal to acquire a significant interest in Catalyst’s equity or assets. Notwithstanding such restrictions, the merger agreement provides that, under specified circumstances occurring before Catalyst stockholders approve the proposal to adopt the merger agreement, if Catalyst receives an unsolicited proposal from a third party to acquire a significant interest in Catalyst that its board of directors concludes in good faith constitutes a Catalyst superior proposal (as described under “The Merger Agreement—No Solicitation of Alternative Transactions by Catalyst” beginning on page 127), or could reasonably be expected to result in a Catalyst superior proposal and the Catalyst board of directors concludes in good faith that failure to negotiate with such third party would be inconsistent with the exercise of its fiduciary duties to the stockholders of Catalyst under applicable law, Catalyst may furnish nonpublic information to that third party and engage in negotiations regarding an acquisition proposal with that third party.

No Solicitation of Alternative Transactions by SXC (see page 129)

Subject to certain exceptions, the merger agreement precludes SXC from soliciting or engaging in discussions or negotiations with a third party with respect to a proposal to acquire a significant interest in SXC’s equity or assets. Notwithstanding such restrictions, the merger agreement provides that, under specified circumstances occurring before SXC shareholders approve the proposal to issue shares pursuant to the merger agreement, if SXC receives an unsolicited bona fide written proposal from a third party to acquire a significant interest in SXC that its board of directors concludes in good faith constitutes an SXC superior proposal (as described under “The Merger Agreement—No Solicitation of Alternative Transactions by SXC” beginning on page 129), or could reasonably be expected to result in an SXC superior proposal and the SXC board of directors concludes in good faith that failure to negotiate with such third party would be inconsistent with its fiduciary duties to the shareholders of SXC under applicable laws, SXC may furnish nonpublic information to that third party and engage in negotiations regarding an acquisition proposal with that third party.

Termination of the Merger Agreement (see page 144)

Termination by SXC or Catalyst

The merger agreement may be terminated at any time prior to the completion of the merger by the mutual written consent of SXC, US Corp., Merger Sub, Merger LLC and Catalyst. Also, subject to certain qualifications and exceptions, either SXC or Catalyst may terminate the merger agreement at any time prior to the completion of the merger if:

Termination by Catalyst

Catalyst may terminate the merger agreement in order to concurrently enter into a binding written agreement concerning a transaction that constitutes a Catalyst superior proposal at any time prior to the approval of the proposal to adopt the merger agreement by Catalyst’s stockholders if (subject to certain qualifications and exceptions):

Catalyst may also terminate the merger agreement if:

In addition, Catalyst may terminate the merger agreement if:

Catalyst may also terminate the merger agreement at any time prior to the effective time if (subject to certain qualifications and exceptions) SXC breaches or fails to perform any of its representations, warranties, covenants or other agreements, which breach or failure to perform would result in a failure of any of the conditions to Catalyst’s obligations to complete the merger relating to the accuracy of SXC’s representations and warranties or its compliance with covenants.

Termination by SXC

SXC may terminate the merger agreement in order to concurrently enter into a binding written agreement concerning a transaction that constitutes an SXC superior proposal at any time prior to the approval of the proposal to adopt the merger agreement by SXC’s shareholders if (subject to certain qualifications and exceptions):

SXC may also terminate the merger agreement if:

In addition, SXC may terminate the merger agreement at any time prior to the completion of the merger if (subject to certain qualifications and exceptions) Catalyst breaches or fails to perform any of its representations, warranties, covenants or other agreements, which breach or failure to perform would result in a failure of any of the conditions to SXC’s obligation to complete the merger relating to the accuracy of Catalyst’s representations and warranties or its compliance with covenants.

Termination Fees and Expenses (see page 147)

If the merger agreement is terminated, Catalyst may be required in specified circumstances to pay a termination fee of $134,500,000 to SXC, and SXC may be required in specified circumstances to pay a termination fee of $134,500,000 to Catalyst. In the event of a termination of the merger agreement due to failure of financing for the transactions, SXC may be required to pay a termination fee of $281,500,000 to Catalyst. If the merger agreement is terminated under certain circumstances, Catalyst or SXC may be required to reimburse the other party for its expenses incurred in connection with the merger in an aggregate amount not to exceed $41,400,000.

Taxation (see page 96)

Material U.S. Federal Income Tax Consequences

The U.S. federal income tax consequences of the merger to holders of Catalyst common stock in general depend on whether the transactions contemplated by the merger agreement qualify for U.S. federal income tax purposes as a “reorganization” under Section 368(a) of the Internal Revenue Code of 1986, as amended, which we refer to as the Internal Revenue Code.

Provided the tax opinions described below are received by Catalyst and SXC on or prior to the closing date of the merger, Catalyst, as the surviving corporation from the merger, will merge with and into Merger LLC in the subsequent merger. If the tax opinions are received and the subsequent merger occurs, SXC and Catalyst will each treat the merger and the subsequent merger, taken together, for all tax purposes as a “reorganization” under Section 368(a) of the Internal Revenue Code.

For the subsequent merger to occur, Catalyst must receive an opinion from its special counsel, Milbank, Tweed, Hadley & McCloy LLP, which we refer to as Milbank, to the effect that, among other things, the merger and the subsequent merger, taken together, should be treated for U.S. federal income tax purposes as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code, and SXC must receive an opinion from its special counsel, Sidley Austin LLP, which we refer to as Sidley, to the effect that none of Catalyst, the surviving corporation in the merger, US Corp., SXC or Merger LLC will recognize income or gain for U.S. federal income tax purposes as a result of the subsequent merger.

If either Catalyst or SXC does not receive such an opinion from its counsel, the subsequent merger will not occur and Catalyst and SXC will each treat the merger for U.S. federal income tax purposes as a taxable

acquisition of the Catalyst common stock by US Corp. in exchange for the merger consideration. In that event, U.S. holders of Catalyst common stock will recognize gain or loss in an amount equal to the difference between the fair market value of the merger consideration at the effective time of the merger and the holder’s tax basis in the shares of Catalyst common stock given up in the exchange.

If the subsequent merger occurs, and the merger and the subsequent merger, taken together, qualify as a “reorganization” under Section 368(a) of the Internal Revenue Code, U.S. holders (subject to limited exceptions for certain holders) whose Catalyst common stock is exchanged in the merger for merger consideration generally will recognize gain (but not loss) on the exchange in an amount not exceeding the amount of cash received. Under that rule, as a result of the cash received in the merger a Catalyst stockholder might recognize all or a significant portion of any gain on the exchange even if the merger and subsequent merger, taken together, qualify as a “reorganization.”

Delivery of these opinions of Sidley and Milbank is not a condition to the closing of the merger, however, and SXC and Catalyst expect to receive these opinions only if certain conditions exist at the time of the merger, as described in “The Merger—Taxation—Material U.S. Federal Income Tax Consequences—U.S. Federal Tax Characterization of the Transactions Contemplated by the Merger Agreement.” No assurance can be given that the opinions will be delivered. It will not be known at the time of the special meetings of the SXC and Catalyst stockholders whether the opinions will be delivered and therefore the U.S. federal income tax treatment of the transactions contemplated by the merger agreement will not be known at such time.

Furthermore, even if the opinions of Sidley and Milbank are received and the parties treat the transactions contemplated by the merger agreement as a “reorganization,” the Internal Revenue Service might successfully assert a contrary position.

For a more detailed description of the U.S. federal income tax consequences of the exchange of Catalyst shares in the merger, see “The Merger—Taxation—Material U.S. Federal Income Tax Consequences” beginning on page 96.

Material Canadian Federal Income Tax Consequences

A Canadian holder (as defined under “The Merger—Taxation—Material Canadian Federal Income Tax Consequences” beginning on page 105) will realize a capital gain (or a capital loss) on the disposition of Catalyst common stock pursuant to the merger, to the extent that aggregate of the amount of cash and fair market value of the SXC common stock received pursuant to the merger, net of any reasonable costs of disposition, exceeds (or is exceeded by) the adjusted cost base of the Catalyst common stock to the Canadian holder immediately before the merger.

The cost to a Canadian holder of each share of SXC common stock received pursuant to the merger will be equal to the fair market value of each share of the SXC common stock at the time of the merger. The adjusted cost base to a Canadian holder of SXC common stock acquired pursuant to the merger will be determined by averaging the cost of the SXC common stock so acquired with the adjusted cost base of all other SXC common stock held at that time by the Canadian holder as capital property.

For a more detailed description of the Canadian federal income tax consequences of the exchange of Catalyst shares in the merger, see “The Merger—Taxation—Material Canadian Federal Income Tax Consequences” beginning on page 105.

Accounting Treatment (see page 108)

SXC will account for the acquisition of shares of Catalyst common stock through the merger under the acquisition method of accounting for business combinations. In determining the acquirer for accounting purposes, SXC considered the factors required under Financial Accounting Standards Board Accounting Standards Codification 805, Business Combinations , which we refer to as ASC 805, and determined that SXC will be considered the acquirer of Catalyst for accounting purposes.

Risk Factors (see page 29)

In evaluating the merger, the merger agreement or the issuance of shares of SXC common stock pursuant to the merger agreement, you should carefully read this joint proxy statement/prospectus and especially consider the factors discussed in the section entitled “Risk Factors” beginning on page 29.

SXC’s Dividend Policy

SXC has never paid a cash dividend on its common stock and has no present intention to commence the payment of cash dividends. It is possible that the board of directors could determine in the future, based on SXC’s financial and other relevant circumstances at that time, to pay cash dividends. See “The Merger—SXC’s Dividend Policy” on page 94.

Comparison of Rights of SXC Shareholders and Catalyst Stockholders (see page 180)

Catalyst is a Delaware corporation. SXC is a Yukon, Canada corporation. The shares of SXC common stock that Catalyst stockholders will receive in the merger will be shares of a Yukon corporation. Catalyst stockholder rights under Delaware law and SXC shareholder rights under Yukon law are different. In addition, SXC’s articles of continuance and its bylaws contain provisions that are different from Catalyst’s certificate of incorporation and bylaws as currently in effect. Certain of these differences are described in detail under “Comparison of Rights of SXC Shareholders and Catalyst Stockholders” beginning on page 180.

Expenses (see page 153)

Generally, all fees and expenses incurred in connection with the merger, merger agreement and the transactions contemplated by the merger agreement will be paid by the party incurring those expenses, subject to the specific exceptions discussed in this joint proxy statement/prospectus.

Summary Selected Historical Financial Data for SXC

The following tables set forth the selected historical consolidated financial data for SXC. The selected consolidated financial data as of December 31, 2011 and 2010 and for the years ended December 31, 2011, 2010 and 2009 have been derived from SXC’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the year ended December 31, 2011, which is incorporated by reference into this joint proxy statement/prospectus. The selected consolidated financial data as of December 31, 2009, 2008 and 2007 and for the years ended December 31, 2008 and 2007 have been derived from SXC’s audited consolidated financial statements and related notes for such years, which have not been incorporated by reference into this joint proxy statement/prospectus. The selected consolidated financial data as of and for the three months ended March 31, 2012 and 2011 have been derived from SXC’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2012, which is incorporated by reference into this joint proxy statement/prospectus. The results for the three months ended March 31, 2012 and 2011 are not necessarily indicative of the results that may be expected for the entire fiscal year. SXC’s unaudited interim financial statements reflect all adjustments that management of SXC considers necessary for the fair presentation of the financial position and results of operations for such periods in accordance with United States generally accepted accounting principles, which we refer to as GAAP. Historical results are not necessarily indicative of the results that may be expected for any future period.

This selected consolidated financial data should be read in conjunction with SXC’s audited consolidated financial statements, the notes related thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in SXC’s Annual Report on Form 10-K for the year ended December 31, 2011 and SXC’s unaudited consolidated financial statements, the notes related thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in SXC’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2012. See “Additional Information—Where You Can Find More Information” beginning on page 233.

Summary Selected Historical Financial Data for Catalyst

The following tables set forth the selected historical consolidated financial data for Catalyst. The selected consolidated financial data as of December 31, 2011 and 2010 and for the fiscal years ended December 31, 2011, 2010 and 2009 have been derived from Catalyst’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the fiscal year ended December 31, 2011, which is incorporated by reference into this joint proxy statement/prospectus. The selected consolidated financial data as of December 31, 2009, 2008 and 2007 and for the fiscal years ended December 31, 2008 and 2007 have been derived from Catalyst’s audited consolidated financial statements and related notes for such years, which have not been incorporated by reference into this joint proxy statement/prospectus. The selected consolidated financial data as of and for the three months ended March 31, 2012 and 2011 have been derived from Catalyst’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2012, which is incorporated by reference into this joint proxy statement/prospectus. The results for the three months ended March 31, 2012 and 2011 are not necessarily indicative of the results that may be expected for the entire fiscal year. Catalyst’s unaudited interim financial statements reflect all adjustments that management of Catalyst considers necessary for the fair presentation of the financial position and results of operations for such periods in accordance with GAAP. Historical results are not necessarily indicative of the results that may be expected for any future period.

This selected consolidated financial data should be read in conjunction with Catalyst’s audited consolidated financial statements, the notes related thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in Catalyst’s Annual Report on Form 10-K for the fiscal year ended December 31, 2011 and Catalyst’s unaudited consolidated financial statements, the notes related thereto and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in Catalyst’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2012. See “Additional Information—Where You Can Find More Information” beginning on page 233.

Summary Selected Unaudited Pro Forma Condensed Combined Financial Information

The following selected unaudited pro forma condensed combined statement of operations data for the three months ended March 31, 2012 and the year ended December 31, 2011 reflect the merger and related financing transactions as if they had occurred on January 1, 2011. The following selected unaudited pro forma condensed combined balance sheet data as of March 31, 2012 reflect the merger and related financing transactions as if they had occurred on March 31, 2012.

The unaudited pro forma condensed combined financial data is based on the historical financial statements of SXC and Catalyst and certain assumptions and adjustments as discussed in the section entitled “SXC Health Solutions Corp. and Catalyst Health Solutions, Inc. Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 160, including assumptions relating to the allocation of the consideration paid for Catalyst based on preliminary estimates of the fair value of the assets acquired and liabilities assumed. This unaudited pro forma condensed combined financial information is provided for illustrative purposes only and is not necessarily indicative of what the operating results or financial position of SXC or Catalyst would have been had the merger and related transactions been completed at the beginning of the period or on the date indicated, nor are they necessarily indicative of any future operating results or financial position. SXC and Catalyst may have performed differently had they been combined during the period presented. The following should be read in connection with the section of this joint proxy statement/prospectus entitled “SXC Health Solutions Corp. and Catalyst Health Solutions, Inc. Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 160 and other information included in or incorporated by reference into this joint proxy statement/prospectus.

Unaudited Pro Forma Combined Per Share Information

The following selected unaudited pro forma combined per share information for the three months ended March 31, 2012 and the year ended December 31, 2011 reflects the merger and related financing transactions as if they had occurred on January 1, 2011. The unaudited pro forma combined book value per common share reflects the merger and related financing transactions as if they had occurred on March 31, 2012.

The unaudited pro forma combined per share information is based on the historical financial statements of SXC and Catalyst and certain assumptions and adjustments as discussed in the section entitled “SXC Health Solutions Corp. and Catalyst Health Solutions, Inc. Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 160, including assumptions relating to the allocation of the consideration paid based on preliminary estimates of the fair values of the assets acquired and liabilities assumed. This unaudited pro forma combined per share information is provided for illustrative purposes only and is not necessarily indicative of what the operating results or financial position of SXC or Catalyst would have been had the merger and related transactions been completed at the beginning of the period or on the date indicated, nor are they necessarily indicative of any future operating results or financial position. SXC and Catalyst may have performed differently had they been combined during the period presented. The following should be read in connection with the section entitled “SXC Health Solutions Corp. and Catalyst Health Solutions, Inc. Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page 160, and other information included in or incorporated by reference into this joint proxy statement/prospectus.