X0306 4 2019-02-21 0 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 2019-02-21 4 A 0 12260 0.00 A 55053 D Settlement of performance shares granted January 22, 2016 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 31, 2020 and January 31, 2021. Exhibit 24 - Power of Attorney /s/ Scott Pintoff, as Attorney-in-Fact for Nicholas Themelis 2019-02-21