X0306 4 2021-08-18 0 0001402829 Orion Group Holdings Inc ORN 0001476693 Buchler Peter R. 12000 AEROSPACE AVENUE SUITE 300 HOUSTON TX 77034 0 1 0 0 EVP and General Counsel Common Stock 2021-08-18 4 A 0 111913 A 405356 D Common Stock 2021-08-18 4 F 0 20900 5.44 D 384456 D Common Stock 2021-08-20 4 F 0 5253 5.31 D 379203 D Represents the number of shares earned under a performance award granted on May 21, 2020. One half of the shares vested on August 18, 2021, with the remaining half vesting in two equal installments on August 18, 2022 and August 18, 2023, subject to the Reporting Person's continued employment through the applicable vesting date. Reflects a reduction of shares of performance-based stock withheld to cover taxes payable by the Reporting Person due to the vesting of shares on August 18, 2021. Reflects a reduction of shares of performance-based stock withheld to cover taxes payable by the Reporting Person due to the vesting of shares on August 20, 2021. Peter R. Buchler 2021-08-20