Horizon Pharma Announces Closing Of Public Offering Of Ordinary Shares And Full Exercise Of Underwriters' Option To Purchase Additional Shares

DUBLIN, IRELAND--(Marketwired - April 21, 2015) - Horizon Pharma plc (NASDAQ: HZNP), a specialty biopharmaceutical company focused on improving patients' lives by identifying, developing, acquiring and commercializing differentiated products that address unmet medical needs, today announced the closing of its underwritten public offering of 17,652,500 of its ordinary shares at a price to the public of $28.25 per share. This includes the exercise in full by the underwriters of their option to purchase up to 2,302,500 additional ordinary shares. The aggregate net proceeds to Horizon from this offering were approximately $475.2 million, after deducting underwriting discounts and other offering expenses payable by Horizon.

Citigroup, Jefferies LLC, Cowen and Company, LLC and Morgan Stanley & Co. LLC acted as joint book-running managers for this offering.

A registration statement relating to the shares described above was previously filed with and became effective by rule of the Securities and Exchange Commission ("SEC"). A final prospectus supplement and accompanying prospectus related to the offering was filed with the SEC and is available on the SEC's website located at http://www.sec.gov. Copies of the final prospectus supplement and accompanying prospectus may be obtained by contacting Citigroup, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, by email at prospectus@citi.com or by phone at 800-831-9146; Jefferies LLC, Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York, NY 10022, or by telephone at (877) 547-6340 or by email at Prospectus_Department@Jefferies.com; Cowen and Company, LLC, c/o Broadridge Financial Services, 1155 Long Island Avenue, Edgewood, NY, 11717, Attn: Prospectus Department or by calling (631) 274-2806; or Morgan Stanley & Co. LLC, 180 Varick Street, 2nd Floor, New York, NY 10014, Attention: Prospectus Department.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, the shares in any state or other jurisdiction which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or other jurisdiction.

About Horizon Pharma plc

Horizon Pharma plc is a specialty biopharmaceutical company focused on improving patients' lives by identifying, developing, acquiring and commercializing differentiated products that address unmet medical needs. The company markets a portfolio of products in arthritis, inflammation and orphan diseases. The company's U.S. marketed products are ACTIMMUNE® (interferon gamma-1b), DUEXIS® (ibuprofen/famotidine), PENNSAID® (diclofenac sodium topical solution) 2% w/w, RAYOS® (prednisone) delayed-release tablets and VIMOVO® (naproxen/esomeprazole magnesium). Horizon's global headquarters are in Dublin, Ireland.

Additional Information and Where to Find It

This communication is neither an offer to purchase nor a solicitation of an offer to sell any shares of common stock of Hyperion Therapeutics, Inc. ("Hyperion") or any other securities. On April 9, 2015, Horizon Pharma plc filed a tender offer statement on Schedule TO with the SEC and, on the same date, a Solicitation/ Recommendation Statement on a Schedule 14D-9 was filed with the SEC by Hyperion. The offer to purchase shares of Hyperion common stock will only be made pursuant to the offer to purchase, the letter of transmittal and related documents filed as a part of the Schedule TO. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ BOTH THE TENDER OFFER STATEMENT, AS FILED AND AS IT MAY BE AMENDED FROM TIME TO TIME, AND THE SOLICITATION/ RECOMMENDATION STATEMENT, AS FILED AND AS MAY BE AMENDED FROM TIME TO TIME, BECAUSE THEY CONTAIN IMPORTANT INFORMATION REGARDING THE TENDER OFFER. Investors and security holders may obtain a free copy of these statements and other documents filed with the SEC at the website maintained by the SEC at www.sec.gov or by directing such requests to Georgeson Inc., the Information Agent for the tender offer, at (866) 856-2826.