X0306 4 2018-01-11 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 2018-01-11 4 S 0 3100 10.01 D 223366 I By 20 20 Holdings, LLC Common Stock, par value $0.01 2018-01-12 4 S 0 1100 10.00 D 222266 I By 20 20 Holdings, LLC Common Stock, par value $0.01 2018-01-12 5 G 0 E 834 0.00 D 5000 D Common Stock, par value $0.01 2018-01-12 5 G 0 E 834 0.00 A 223100 I By 20 20 Holdings, LLC Common Stock, par value $0.01 2018-01-16 4 S 0 7500 10.02 D 215600 I By 20 20 Holdings, LLC The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by 20 20 Holdings, LLC and Mr. Irvin on November 17, 2017. The price reported in Column 4 is a weighted average price. The shares sold on January 11, 2018 were sold in multiple transactions at prices ranging from $10.00 to $10.03, inclusive. The shares sold on January 16, 2018 were sold in multiple transactions at prices ranging from $10.00 to $10.07, 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 ranges 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. Represents a gift of shares by Mr. Irvin to 20 20 Holdings, LLC. /s/ Loretta L. Benec, attorney-in-fact for John Irvin 2018-01-16