UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549





FORM 10-K/A

(Amendment No. 1)





(Mark One)

|☒ | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------

For the fiscal year ended December 31, 2015

or



|☐ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

For the transition period from
 to

Commission File Number 001-35238





HORIZON PHARMA PUBLIC LIMITED COMPANY

(Exact name of Registrant as specified in its charter)







|                                                                          |  |                                     
|------------------------------------------------------------------------- |  | ------------------------------------
|Ireland                                                                   |  | Not Applicable                      
|(State or other jurisdiction of
incorporation or organization)            |  | (I.R.S. Employer
Identification No.)
|                                                                          | 
|Connaught House, 1st Floor
1 Burlington Road, Dublin 4, D04 C5Y6, Ireland |  | Not Applicable                      
|(Address of principal executive offices)                                  |  | (zip code)                          

011 353 1 772 2100

(Registrants telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:



|                                                 |  |                                          
|------------------------------------------------ |  | -----------------------------------------
|Title of Each Class                              |  | Name of Each Exchange on Which
Registered
|Ordinary shares, nominal value $0.0001 per share |  | The NASDAQ Global Select Market          

Securities registered pursuant to Section 12(g) of the Act:

None





Indicate by
check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ☒    No  ☐.

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the
Act.    Yes  ☐    No  ☒.

Indicate by check mark whether the
registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data
File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such
files).    Yes  ☒    No  ☐

Indicate by check mark if disclosure
of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the registrants knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  ☒

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a
non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of large accelerated filer, accelerated filer, smaller reporting
company, and emerging growth company in Rule 12b-2 of the Exchange Act.



|                        |  |                                                  |  |                           |  |  
|----------------------- |  | ------------------------------------------------ |  | ------------------------- |  | -
|Large accelerated filer |  | ☒                                                |  | Accelerated filer         |  | ☐
|                        |  |                                                  | 
|Non-accelerated filer   |  | ☐  (Do not check if a smaller reporting company) |  | Smaller reporting company |  | ☐
|                        |  |                                                  | 
|                        |  |                                                  |  | Emerging growth company   |  | ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended
transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the
Exchange Act).    Yes  ☐    No  ☒

The aggregate market value of
the registrants voting ordinary shares held by non-affiliates of the registrant, based upon the $34.74 per share closing sale price of the registrants ordinary shares on June 30, 2015 (the
last business day of the registrants most recently completed second quarter), was approximately $4.7 billion. Solely for purposes of this calculation, the registrants directors and executive officers and holders of 10% or more of
the registrants outstanding ordinary shares have been assumed to be affiliates and an aggregate of 21,858,502 shares of the registrants voting ordinary shares held by such persons on June 30, 2015 are not included in this
calculation.

As of February 23, 2016, the registrant had outstanding 159,884,455 ordinary shares.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrants definitive Proxy Statement for the registrants 2016 Annual Meeting of Shareholders are incorporated by
reference into Part III of the registrants Annual Report on Form 10-K.









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EXPLANATORY NOTE

Horizon Pharma Public Limited Company (the Company) is filing this Amendment No. 1 to Annual Report on
Form 10-K/A (this Amendment) to amend the Companys Annual Report on Form 10-K for the fiscal year ended December 31, 2015, as filed with the
Securities and Exchange Commission (the SEC) on February 29, 2016 (the 10-K). This Amendment is being filed solely to re-file revised
redacted versions of Exhibits 2.4, 10.61, 10.62 and 10.68 to the 10-K, reflecting changes to the Companys confidential treatment request with respect to certain portions of such exhibits. In addition, as
required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended, new certifications by the Companys principal executive officer and principal financial officer are filed as exhibits to
this Amendment.

No attempt has been made in this Amendment to modify or update the other disclosures presented in the
10-K. This Amendment does not reflect events occurring after the filing of the 10-K or modify or update those disclosures that may be affected by subsequent events.
Accordingly, this Amendment should be read in conjunction with the 10-K and the registrants other filings with the SEC.



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SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the registrant has duly caused
this Annual Report on Form 10-K/A to be signed on its behalf by the undersigned, thereunto duly authorized.



Horizon Pharma plcBy:

/s/ Paul W. HoelscherPaul W. HoelscherExecutive Vice President and Chief Financial Officer
(Principal Financial Officer)


Dated: May 26, 2017



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INDEX TO EXHIBITS



|              |  |                                                                                                                                                                                                                                                                                                                        
|------------- |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|ExhibitNumber |  | Description of Document                                                                                                                                                                                                                                                                                                
|              | 
|2.4**         |  | Agreement and Plan of Merger, dated December 10, 2015, by and among Horizon Pharma USA, Inc., HZNP Limited, Criostail LLC, Crealta Holdings LLC and the other parties thereto.                                                                                                                                       
|              | 
|10.61**       |  | License Agreement, dated August 12, 1998, by and among Mountain View Pharmaceuticals, Inc., Duke University and Crealta Pharmaceuticals LLC (as successor in interest to Bio-Technology
General Corporation), as amended November 12, 2001, August 30, 2010, March 12, 2014 and July 16, 2015.                         
|              | 
|10.62**       |  | Commercial Supply Agreement, dated March 20, 2007, by and between Crealta Pharmaceuticals LLC (as successor in interest to Savient Pharmaceuticals, Inc.) and Bio-Technology General
(Israel) Ltd., as amended September 24, 2007, January 24, 2009, July 1, 2010 and March 21, 2012.                                  
|              | 
|10.68**       |  | Commercial Supply Agreement, dated October 16, 2008, by and between Sigma-Tau PharmaSource, Inc. (as successor in interest to Enzon Pharmaceuticals, Inc.) and Crealta Pharmaceuticals LLC
(as successor in interest to Savient Pharmaceuticals, Inc.), as amended October 5, 2009, October 22, 2009 and July 29, 2014.
|              | 
|31.3          |  | Certification of Principal Executive Officer pursuant to Rule 13a-14(a) or 15d-14(a) of the Exchange Act.                                                                                                                                                                                                              
|              | 
|31.4          |  | Certification of Principal Financial Officer pursuant to Rule 13a-14(a) or 15d-14(a) of the Exchange Act.                                                                                                                                                                                                              



| | Schedules have been omitted pursuant to Item 601(b)(2) of Regulation S-K. Horizon Pharma Public Limited Company undertakes to furnish supplemental copies of any of the omitted
schedules upon request by the Securities and Exchange Commission; provided, however, that Horizon Pharma Public Limited Company may request confidential treatment pursuant to Rule 24b-2 of the Securities
Exchange Act of 1934, as amended, for any schedule so furnished.
|-- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|** | Confidential treatment has been requested with respect to certain portions of this exhibit. Omitted portions have been filed separately with the Securities and Exchange Commission.
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