X0306 4 2020-11-09 0 0001278021 MARKETAXESS HOLDINGS INC MKTX 0001296466 McVey Richard M C/O MARKETAXESS HOLDINGS INC. 55 HUDSON YARDS, 15TH FLOOR NEW YORK NY 10001 1 1 0 0 Chairman & CEO Common Stock, par value $0.003 per share 2020-10-29 5 G 0 E 50000 0.00 D 881283 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1492 534.43 D 879791 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1461 535.60 D 878330 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 300 536.39 D 878030 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 985 537.38 D 877045 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 968 538.64 D 876077 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1402 539.63 D 874675 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 300 540.84 D 874375 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 200 542.24 D 874175 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 302 543.93 D 873873 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 569 545.31 D 873304 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1048 546.36 D 872256 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1406 547.52 D 870850 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 333 548.55 D 870517 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 510 549.31 D 870007 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 325 550.57 D 869682 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 698 551.83 D 868984 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 680 552.61 D 868304 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 922 554.07 D 867382 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1435 554.98 D 865947 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 469 555.71 D 865478 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 568 556.95 D 864910 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 606 557.97 D 864304 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1105 559.14 D 863199 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1499 560.15 D 861700 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 2324 561.17 D 859376 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1400 562.28 D 857976 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 343 563.22 D 857633 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 1038 564.31 D 856595 D Common Stock, par value $0.003 per share 2020-11-09 4 S 0 973 565.46 D 855622 D Represents a bona fide gift of shares as a contribution to a charitable trust by the reporting person. This transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The transactions were executed in multiple trades at prices ranging from $533.96 to $534.89. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $535.13 to $535.99. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $536.14 to $536.86. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $537.19 to $537.78. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $538.23 to $538.97. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $539.26 to $540.15. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $540.37 to $541.06. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $542.15 to $542.33. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $543.47 to $544.21. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $544.80 to $545.78. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $545.92 to $546.81. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $547.04 to $548.02. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $548.04 to $548.98. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $549.04 to $549.64. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $550.05 to $551. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $551.39 to $552.35. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $552.40 to $553.06. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $553.43 to $554.41. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $554.45 to $555.43. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $555.49 to $556.31. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $556.54 to $557.38. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $557.64 to $558.26. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $558.65 to $559.63. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $559.68 to $560.67. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $560.71 to $561.66. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $561.72 to $562.54. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $562.78 to $563.63. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $563.92 to $564.85. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. The transactions were executed in multiple trades at prices ranging from $565 to $565.90. The price above reflects the weighted average sales price. Detailed information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer. This is the first of two Form 4s filed by Mr. McVey on November 12, 2020. /s/ Jason Edelstein, as Attorney-in-Fact for Richard M. McVey 2020-11-12