X0306 4 2019-01-31 0001278021 MARKETAXESS HOLDINGS INC MKTX 0001296468 Themelis Nicholas C/O MARKETAXESS HOLDINGS INC. 299 PARK AVENUE NEW YORK NY 10171 0 1 0 0 Chief Information Officer Common Stock, par value $0.003 per share 2019-01-31 4 A 0 930 0 A 44228 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 323 214.77 D 43905 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 127 214.77 D 43778 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 396 214.77 D 43382 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 198 214.77 D 43184 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 158 214.77 D 43026 D Common Stock, par value $0.003 per share 2019-01-31 4 F 0 233 214.77 D 42793 D Settlement of performance shares granted January 15, 2018 pursuant to the Issuer's 2012 Incentive Plan, which were settled based on the achievement by the Issuer of adjusted pre-tax operating income targets during the performance period and are payable in shares of restricted stock. The shares of restricted stock will vest in two equal installments on January 15, 2020 and January 15, 2021. Represents the surrender of shares to the Company to satisfy Mr. Themelis' tax withholding obligation upon the vesting of restricted stock previously granted to Mr. Themelis. Represents the surrender of shares to the Company to satisfy Mr. Themelis' tax withholding obligation upon the vesting of restricted stock units previously granted to Mr. Themelis. /s/ Ori Solomon, as Attorney-in-Fact for Nicholas Themelis 2019-02-04