Shareholders' Equity

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Shareholders' Equity

Shareholders' Equity

Ordinary Shares

As of December 31, 2014, the Company had 100,000,000 ordinary shares authorized for issuance with a par value of $0.01 per ordinary share and 27,388,005 ordinary shares issued and outstanding. Each ordinary share is entitled to one vote and, on a pro rata basis, to dividends when declared and the remaining assets of the Company in the event of a winding up.

Euro Deferred Shares

As of December 31, 2014, the Company had 10,000 Euro Deferred Shares authorized for issuance with a nominal value of €22 per share. No Euro Deferred Shares are outstanding at December 31, 2014. The rights and restrictions attaching to the Euro Deferred Shares rank pari passu with the ordinary shares and are treated as a single class in all respects.

February 2014 Offering

In February 2014, Elan Science One Limited ("ESOL"), an indirect wholly owned subsidiary of Perrigo, sold 3,182,253 ordinary shares of Prothena at a price to the public of $26.00 per ordinary share, before the underwriting discount. As a result, ESOL and Perrigo no longer own any ordinary shares of Prothena.

The Company did not receive any of the proceeds from the offering, and the total number of the Company's ordinary shares outstanding did not change as a result of this offering. The Company paid the costs associated with the sale of these ordinary shares (other than the underwriting discount, fees and disbursements of counsel for the selling shareholder) pursuant to a Subscription and Registration Rights Agreement dated November 8, 2012 by and between the Company, Elan and ESOL.

June 2014 Offering

In June 2014, the Company completed an underwritten public offering of an aggregate of 4,750,000 of its ordinary shares at a public offering price of $22.50 per ordinary share. The Company received aggregate net proceeds of approximately $102.5 million, after deducting the underwriting discount and estimated offering costs.

In connection with this offering, the Company granted the underwriters the right to subscribe for and purchase, as applicable, up to an additional 712,500 ordinary shares. In July 2014, the underwriters exercised such right to subscribe for and purchase an aggregate of 712,500 ordinary shares, pursuant to which the Company received net proceeds of approximately $14.9 million, after deducting the underwriting discount of approximately $1.1 million.

For the year ended December 31, 2014 underwriting discount and offering expense of $5.5 million were classified as an offset to the proceeds and recorded in additional paid in capital on the balance sheet.

October 2013 Offering

In October 2013, the Company completed an underwritten public offering of an aggregate of 6,796,500 of its ordinary shares at a public offering price of $22.00 per share, which consisted of 4,177,079 newly issued ordinary shares sold by the Company and 2,619,421 ordinary shares sold by Janssen Pharmaceutical, a wholly-owned subsidiary of Johnson & Johnson, as the selling shareholder. The Company received aggregate net proceeds of approximately $84.5 million, after deducting the underwriting discount and estimated offering costs. The Company did not receive any proceeds from the sale of 2,619,421 ordinary shares sold, which represented Janssen Pharmaceutical's entire shareholding in Prothena.

During the year ended December 31, 2013 underwriting discounts and offering costs of $7.4 million were recorded as an offset to the proceeds and recorded in additional paid in capital.