UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549





FORM 10-Q/A

(Amendment No. 1)





(MARK ONE)

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

For the quarterly period ended September 30, 2016

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)

Not applicable

(Former
name, former address and former fiscal year, if changed since last report)





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 Web site, if any, every Interactive Data File required
to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) 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 whether the registrant is a
large accelerated filer, an accelerated filer, a non-accelerated filer, 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 in Rule 12b-2 of the Exchange
Act).    Yes  ☐    No  ☒

Number of registrants ordinary shares, nominal
value $0.0001, outstanding as of November 2, 2016: 161,257,419.









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EXPLANATORY NOTE

Horizon Pharma Public Limited Company (the Company) is filing this Amendment No. 1 to Quarterly Report on Form 10-Q/A (this
Amendment) to amend the Companys Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2016, as filed with the Securities and Exchange Commission (the SEC) on November 7, 2016 (the
10-Q). This Amendment is being filed solely to re-file a revised redacted version of Exhibit 10.5 to the 10-Q, reflecting changes to the Companys confidential treatment request with respect to certain portions of such exhibit. 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-Q. This
Amendment does not reflect events occurring after the filing of the 10-Q or modify or update those disclosures that may be affected by subsequent events. Accordingly, this Amendment should be read in conjunction with the 10-Q and the
registrants other filings with the SEC.



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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.



|                   |  |  |  |                    |  |                                                                                
|------------------ |  |  |  | ------------------ |  | -------------------------------------------------------------------------------
|                   |  |  |  | HORIZON PHARMA PLC
|                   |  |  | 
|Date: May 26, 2017 |  |  |  | By:                |  | /s/ Timothy P. Walbert                                                         
|                   |  |  |  |                    |  | Timothy P. Walbert                                                             
|                   |  |  |  |                    |  | Chairman, President and Chief Executive Officer
(Principal Executive Officer)  
|                   |  |  | 
|Date: May 26, 2017 |  |  |  | By:                |  | /s/ Paul W. Hoelscher                                                          
|                   |  |  |  |                    |  | Paul W. Hoelscher                                                              
|                   |  |  |  |                    |  | Executive Vice President, Chief Financial Officer
(Principal Financial Officer)



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INDEX TO EXHIBITS



|               |  |                                                                                                                                                                                                                                                                                                                             
|-------------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Exhibit
Number |  | Description of Document                                                                                                                                                                                                                                                                                                     
|               | 
|10.5*          |  | Manufacturing Services Agreement, dated November 15, 2010, by and among Patheon Pharmaceuticals Inc., Horizon Orphan LLC (as successor in interest to Raptor Therapeutics Inc.) and Horizon Pharma Europe B.V. (as successor in
interest to Raptor Pharmaceuticals Europe B.V.), as amended April 5, 2012 and June 21, 2013.
|               | 
|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.                                                                                                                                                                                                                   



|* | 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.
|- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------