Ablynx : 16/01/2018 PUBLICATION IN ACCORDANCE WITH ARTICLE 14 OF THE BELGIAN LAW OF 2 MAY 2007 REGARDING THE PUBLICATION OF MAJOR SHAREHOLDINGS (THE "TRANSPARENCY LAW")

REGULATED INFORMATION

PUBLICATION IN ACCORDANCE WITH ARTICLE 14 OF THE BELGIAN LAW OF

2 MAY 2007 REGARDING THE PUBLICATION OF MAJOR SHAREHOLDINGS

(THE "TRANSPARENCY LAW")

GHENT, Belgium, 16 January 2018 - Ablynx [Euronext Brussels and Nasdaq: ABLX] today announced, in accordance with Article 14 of the Belgian Law of 2 May 2007 regarding the publication of major shareholdings in issuers whose securities are admitted to trading on a regulated market (the "Transparency Law"), that it received a notification of shareholdings from Marshall Wace LLP on 12 January 2018.

Marshall Wace LLP notified Ablynx that as a result of an acquisition of voting securities, it has crossed the 3% threshold on 8 January 2018 and now holds 2,251,187 voting securities of Ablynx, representing 3.01% of the current 74,720,644 outstanding voting rights of Ablynx.

The notification contains the following information:

• - Reason for the notification: acquisition or disposal of voting securities or voting rights

• - Notification by: a person that notifies alone

• - Persons subject to the notification requirement: Marshall Wace LLP

• - Transaction date: 8 January 2018

• - Threshold that is crossed: 3%

• - Denominator: 74,720,644

• - Details of the notification: Marshall Wace LLP holds 2,251,187 Ablynx shares with voting rights

• - Chain of controlled undertakings through which the holding is effectively being held: Marshall Wace LLP is not a controlled entity in respect of the exercise of the voting rights held in the issuer.

• - Additional information: This disclosure is provided by Marshall Wace LLP which has been appointed as investment manager or trading adviser acting for and on behalf of certain funds and managed accounts. Marshall Wace LLP exercise voting rights at its own discretion, without specific instructions from third parties or affiliates.

More information is provided in the transparency notification. A full version of the transparency notification is available on Ablynx website, under the sectionInvestors.

The Articles of the Association of Ablynx NV provide for shareholders notification threshold of 3%, 5% or a multiple of 5% of the total number of existing voting rights.

About Ablynx

Ablynx is a biopharmaceutical company engaged in the development of Nanobodies, proprietary therapeutic proteins based on single-domain antibody fragments, which combine the advantages of conventional antibody drugs with some of the features of small-molecule drugs. Ablynx is dedicated to creating new medicines which will make a real difference to society. Today, the Company has more than 45 proprietary and partnered programmes in development in various therapeutic areas including inflammation, haematology, immuno-oncology, oncology and respiratory disease. The Company has collaborations with multiple pharmaceutical companies including AbbVie; Boehringer Ingelheim; Eddingpharm; Merck & Co.,Inc., Kenilworth, New Jersey, USA; Merck KGaA; Novartis; Novo Nordisk; Sanofi and Taisho Pharmaceuticals. The Company is headquartered in Ghent, Belgium. More information can be found onwww.ablynx.com.

For more information, please contact: Ablynx

Dr Edwin Moses CEO t: +32 (0)9 262 00 07 m: +32 (0)473 39 50 68 e:edwin.moses@ablynx.com

@AblynxABLX

Ablynx media relations:

Lies Vanneste Director IR t: +32 (0)9 262 0137 m: +32 (0)498 05 35 79 e:lies.vanneste@ablynx.com

Consilium Strategic Communications Mary-Jane Elliott, Philippa Gardner, Sukaina Virji t: +44 (0)20 3709 5700 e:ablynx@consilium-comms.com