X0508 4 2026-03-01 0001278021 MARKETAXESS HOLDINGS INC MKTX 0001267209 SCHICIANO KENNETH T C/O MARKETAXESS HOLDINGS INC. 55 HUDSON YARDS, 15TH FLOOR NEW YORK NY 10001 true false false false false Common Stock, par value $0.003 per share 2026-03-01 4 A false 259 0 A 555 D Represents a grant of restricted stock units pursuant to the Company's 2020 Equity Incentive Plan. The restricted stock units will vest on the earlier of the date of the next annual meeting of shareholders or the 1-year anniversary of the grant. /s/ Patrick Wilson as Attorney-in-Fact for Kenneth T. Schiciano 2026-03-02