X0306 4 2017-12-15 0 0000866609 ION GEOPHYSICAL CORP IO 0001481492 Usher Christopher Theron 2105 CITYWEST BOULEVARD SUITE 100 HOUSTON TX 77042-2855 0 1 0 0 EVP & COO, E&P OPER OPTIMIZAT Common Stock 2017-12-15 4 M 0 100000 3.10 A 137367 D Common Stock 2017-12-15 4 D 0 100000 13.05 D 37367 D Common Stock 2017-12-15 4 P 0 14850 13.50 A 52217 D Stock Appreciation Right 3.10 2017-12-15 4 M 0 100000 0.00 D 2017-03-01 2026-03-01 Common Stock 100000 50000 D Exercise of cash-settled SARs. In accordance with the rules for filing Form 4, the exercise of cash-settled SARs is treated as the simultaneous purchase of the number of shares for which SARs are exercised and the sale of the same number of shares. No shares actually changed hands. Compensation Committee approved acceleration of the vesting of the second tranche on 12/13/2017. Final tranche to vest as scheduled on 03/01/2019. Rebecca F. Sacco, attorney-in-fact 2017-12-19