Additional Listing

Horizon Discovery Group plc

Additional Listing

The Company has issued and allotted 92,023 new ordinary shares pursuant to the exercise of options.

Accordingly, application has been made for 92,023 new ordinary shares to be admitted to trading on AIM and it is expected that admission will take place on 30 September 2014.

The new ordinary shares will rank pari passu with the existing shares of the Company.

Following Admission, the Company's enlarged issued share capital will comprise 67,358,351 ordinary shares with one voting right per share. No shares are held in Treasury. The total number of voting rights in the Company is therefore 67,358,351.

This figure of 67,358,351 ordinary shares may be used by shareholders in the Company as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change in their interest in, the share capital of the Company under the FCA's Disclosure and Transparency Rules.

25 September 2014

For further information, please contact:

Consilium Strategic Communications

Amber Bielecka / Mary-Jane Elliott / Jessica Hodgson / Matthew Neal

[email protected]

+44 207 920 2352

Panmure Gordon & Co.

As Nominated Adviser and Broker

Corporate Finance

Freddy Crossley / Duncan Monteith / Fred Walsh

Broking

Tom Salvesen

Tel: +44 20 7886 2500

About Horizon Discovery Group plc

Horizon is a revenue-generating life science company supplying research tools to organizations engaged in genomics research and the development of personalized medicines. Horizon has a diverse and international customer base approaching 800 organizations, including major pharmaceutical, biotechnology and diagnostic companies as well as leading academic research centres. The Company supplies its products and services into multiple markets, estimated to total in excess of GBP29 billion by 2015.

Horizon's core capabilities are built around its proprietary translational genomics platform, GENESIS(TM), a high-precision and flexible suite of gene editing tools. Horizon has applied GENESIS(TM) to create over 500 X-MAN(TM) cell lines, accurately modeling the disease-causing mutations found in genetically based diseases. These 'patients-in-a-test-tube' are being used by customers to identify the effect of individual or compound genetic mutations on drug activity, patient responsiveness, and resistance, which may lead to the successful prediction of which patient sub-groups will respond to currently-available and future drug treatments.

Horizon is headquartered in Cambridge, UK and is listed on the London Stock Exchange's AIM market under the ticker "HZD", for further information please visit: www.horizondiscovery.com