Published July 2015

Celyad Raises $100.1 Million Gross Proceeds With NASDAQ IPO

In addition, Celyad has granted the underwriters an option to purchase up to an additional 175,200 new ordinary shares in the form of ADSs and an option to purchase up to an additional 43,800 new ordinary shares, representing 15% of the ordinary shares and ADSs placed in the global offering. This option can be exercised during the 30 day period commencing 18 June 2015.

The closings of the ADS offering and the concurrent private placement are conditioned on each other and are expected to occur on 24 June 2015, subject to customary closing conditions.

Each of the ADSs offered represents the right to receive one ordinary share.

Celyad’s ordinary shares are currently listed on Euronext Paris and Euronext Brussels, under the symbol “CYAD”. The ADSs are expected to begin trading on the NASDAQ Global

Market on 19 June 2015 under the symbol “CYAD”.

UBS Investment Bank and Piper Jaffray & Co. are acting as joint book-running managers, and Petercam SA, Bryan, Garnier & Co., LifeSci Capital LLC and Lake Street Capital Markets LLC are acting as co-managers for the proposed global offering.

A registration statement relating to these securities was declared effective by the U.S. Securities and Exchange Commission on 18 June 2015.