Mainstay Medical International plc - STANDARD FORM TR-1

Regulatory News:

Mainstay Medical International plc (BOURSE: MSTY)

STANDARD FORM TR-1

VOTING RIGHTS ATTACHED TO SHARES– ARTICLE 12(1) OF DIRECTIVE 2004/109/EC

FINANCIAL INSTRUMENTS – ARTICLE 11(3) OF THE COMMISSION DIRECTIVE 2007/14/EC

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached:

Mainstay Medical International plc

2. Reason for the notification (please tick the appropriate box or boxes):

[X] an acquisition or disposal of voting rights

[ ] an acquisition or disposal of financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

[ ] an event changing the breakdown of voting rights

3. Full name of person(s) subject to the notification obligation:

Perceptive Advisors LLC

4. Full name of shareholder(s) (if different from 3.):

N/A

5. Date of the transaction and date on which the threshold is crossed or reached:

2 May 2014

6. Date on which issuer notified;

9 May 2014

7. Threshold(s) that is/are crossed or reached:

7%

8. Notified details:

9. Chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held, if applicable:

Perceptive Life Sciences Master Fund, Ltd. (no voting rights)

Titan Perc, Ltd. (no voting rights)

10. In case of proxy voting:

N/A

11. Additional information:

N/A