Certain Ordinary Shares of Materialise NV are subject to a Lock-Up Agreement Ending on 9-SEP-2021. These Ordinary Shares will be under lockup for 91 days starting from 10-JUN-2021 to 9-SEP-2021. Details: Each of the directors, executive officers and certain of significant shareholders have agreed that, without the prior written consent of J.P. Morgan Securities LLC on behalf of the underwriters, they will not, subject to limited exceptions, during the period ending 90 days after the date of this prospectus supplement, either directly or indirectly offer, pledge, announce the intention to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, make any short sale or otherwise transfer or dispose of, directly or indirectly, any ADSs.