X0306 4 2020-11-25 0 0001561627 ExOne Co XONE 0001250606 IRVIN JOHN 127 INDUSTRY BOULEVARD NORTH HUNTINGDON PA 15642 1 0 0 0 Common Stock, par value $0.01 2020-11-25 4 S 0 20000 12.16 D 128450 I By 20 20 Holdings, LLC Common Stock, par value $0.01 15000 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $12.15 to $12.18, inclusive. Mr. Irvin undertakes to provide to The ExOne Company, any security holder of The ExOne Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. 20 20 Holdings, LLC is the owner of the listed shares. 20 20 Holdings is a limited liability company beneficially owned by Mr. Irvin's wife and Mr. Irvin, and of which Mr. Irvin is the sole manager and has sole power to vote and dispose of the shares. /s/ Loretta L. Benec, attorney-in-fact for John Irvin 2020-11-30