Exhibit 99.1

MARKETAXESS HOLDINGS INC.

2022 EMPLOYEE STOCK PURCHASE PLAN

FOR US EMPLOYEES

1. Purpose. This MarketAxess Holdings Inc. 2022 Employee Stock Purchase Plan (the “Plan”) is intended to provide employees of the Company and its Participating Subsidiaries with an opportunity to acquire a proprietary interest in the Company through the purchase of shares of Common Stock. The Company intends that the Plan qualify as an “employee stock purchase plan” under Section 423 of the Code and the Plan shall be interpreted in a manner that is consistent with that intent.

2. Definitions.

“Beneficial Owner” shall have the meaning ascribed to such term in Rule 13d-3 under the Exchange Act.

“Board” means the Board of Directors of the Company.

“Cause” has the meaning set forth in the MarketAxess Holdings Inc. 2020 Equity Incentive Plan, or any equity incentive plan that replaces the MarketAxess Holdings Inc. 2020 Equity Incentive Plan.

“Code” means the U.S. Internal Revenue Code of 1986, as it may be amended from time to time. Any reference to a section of the Code shall be deemed to include a reference to any regulations promulgated thereunder.

“Committee” means (i) the Compensation and Talent Committee of the Board, (ii) such other committee of the Board appointed by the Board to administer the Plan or (iii) the Board, as determined by the Board.

“Common Stock” means the common stock of the Company, par value $0.003 per share.

“Company” means MarketAxess Holdings Inc.

“Compensation” means base salary, wages, annual bonuses and overtime paid to an Eligible Employee by the Company or a Participating Subsidiary as compensation for services to the Company or Participating Subsidiary, before deduction for any salary deferral contributions made by the Eligible Employee to any tax-qualified or nonqualified deferred compensation plan.

“Change in Control” shall have to meaning set forth in the MarketAxess Holdings Inc. 2020 Equity Incentive Plan.

“Clawback Discount Value” shall mean the difference between the Fair Market Value and the Purchase Price on the applicable Purchase Date.

“Designated Broker” means the financial services firm or other agent designated by the Company to maintain ESPP Share Accounts on behalf of Participants who have purchased shares of Common Stock under the Plan.

“Effective Date” means the date as of which this Plan is adopted by the Board, subject to the Plan obtaining stockholder approval in accordance with Section 18.10 hereof.

“Employee” means any person who renders services to the Company or a Participating Subsidiary as an employee pursuant to an employment relationship with such employer in accordance with Section 421 of the Code and the Treasury Regulations thereunder.

“Eligible Employee” means an Employee other than (i) an Employee whose customary employment is for less than twenty (20) hours per week, (ii) an Employee whose customary employment is for not more than five (5) months in any calendar year and (iii) an Employee who has been employed for less than sixty (60) days prior to the beginning of an Offering Period. Notwithstanding the foregoing, the Committee may exclude from participation in the Plan or any Offering, Employees who have been employed for less than two years or Employees who are “highly compensated employees” of the Company or a Participating Subsidiary (within the meaning of Section 414(q) of the Code) or a sub-set of such highly compensated employees.

“Enrollment Form” means an agreement pursuant to which an Eligible Employee may elect to enroll in the Plan, to authorize a new level of payroll deductions, or to stop payroll deductions and withdraw from an Offering Period; for the avoidance of doubt, the Enrollment Form may be an online form Eligible Employees complete with the Designated Broker.

“ESPP Share Account” means an account into which Common Stock purchased with accumulated payroll deductions at the end of an Offering Period are held on behalf of a Participant.

“Exchange Act” means the U.S. Securities Exchange Act of 1934, as amended.

“Fair Market Value” means the closing price as reported on the NASDAQ Global Select Market or other principal exchange on which the Common Stock is then listed on such date, or if the Common Stock was not traded on such date, then on the next preceding trading day that the Common Stock was traded on such exchange, as reported by such responsible reporting service as the Committee may select.

“Offering Date” means the first trading day of each Offering Period as designated by the Committee.

“Offering or Offering Period” means the periods established in accordance with Section 5 during which options to purchase shares of Common Stock may be granted pursuant to the Plan and may be purchased on the Purchase Date.

“Participant” means an Eligible Employee who is actively participating in the Plan.

“Participating Subsidiaries” means the Subsidiaries that have been designated as eligible to participate in the Plan by the Committee from time to time in its sole discretion.

“Person” shall have the meaning ascribed to such term in Section 3(a)(9) of the Exchange Act and used in Sections 13(d) and 14(d) thereof, including a “group” as defined in Section 13(d) thereof.

“Plan” means this MarketAxess Holdings Inc. 2022 Employee Stock Purchase Plan, as set forth herein, and as amended from time to time.

“Purchase Date” means the last trading day of each Offering Period.

“Purchase Price” means an amount equal to the lesser of (i) eighty-five percent (85%) (or such greater percentage as designated by the Committee) of the Fair Market Value of a share of Common Stock on the Offering Date or (ii) eighty-five percent (85%) (or such greater percentage as designated by the Committee) of the Fair Market Value of a share of Common Stock on the Purchase Date; provided, that, the Purchase Price per share of Common Stock will in no event be less than the par value of the Common Stock.

“Securities Act” means the Securities Act of 1933, as amended.

“Subsidiary” means an entity (whether or not a corporation) that is wholly or majority owned or controlled, directly or indirectly, by the Company or any other affiliate of the Company that is so designated, from time to time, by the Committee, during the period of such affiliated status. In all cases, the determination of whether an entity is a Subsidiary shall be made in accordance with Section 424(f) of the Code.

“Trading Day” means a day on which the national stock exchange upon which the Common Stock is listed is open for trading.

3. Administration.

3.1 The Plan shall be administered by the Committee which shall have the authority to construe and interpret the Plan, prescribe, amend and rescind rules relating to the Plan’s administration. The Committee may correct any defect or supply any omission or reconcile any inconsistency or ambiguity in the Plan. The decisions of the Committee shall be final and binding on all persons. All expenses of administering the Plan shall be borne by the Company.

3.2 The Committee may establish sub-plans (which need not qualify under section 423 of the Code) and initiate separate Offerings through such sub-plans for the purpose of (i) facilitating participation in the Plan by non-U.S. employees in compliance with foreign laws and regulations without affecting the qualification of the remainder of the Plan under section 423 of the Code or (ii) qualifying the Plan for preferred tax treatment under foreign tax laws (which sub-plans, at the Committee’s discretion, may provide for allocations of the authorized shares reserved for issue under the Plan as set forth in Section 14(a)). The rules, guidelines and forms of such sub-plans (or the Offerings thereunder) may take precedence over other provisions of the Plan, with the exception of Section 12.1, but unless otherwise superseded by the terms of such sub-plan, the provisions of the Plan shall govern the operation of such sub-plan. Alternatively and in order to comply with the laws of a foreign jurisdiction, the Committee shall have the power, in its discretion, to grant options in an Offering to citizens or residents of a non-U.S. jurisdiction (without regard to whether they are also citizens of the United States or resident aliens) that provide terms which are less favorable than the terms of options granted under the same Offering to employees resident in the United States, subject to compliance with section 423 of the Code.

4. Eligibility. Unless otherwise determined by the Committee in a manner that is consistent with Section 423 of the Code, any individual who is an Eligible Employee as of the first day of the enrollment period designated by the Committee for a particular Offering Period shall be eligible to participate in such Offering Period, subject to the requirements of Section 423 of the Code.

Notwithstanding any provision of the Plan to the contrary, no Eligible Employee shall be granted an option under the Plan if (i) immediately after the grant of the option, such Eligible Employee (or any other person whose stock would be attributed to such Eligible Employee pursuant to Section 424(d) of the Code) would own capital stock of the Company and/or hold outstanding options to purchase stock, in the aggregate, possessing 5% or more of the total combined voting power or value of all classes of stock of the Company or any Subsidiary or (ii) such option would permit his or her rights to purchase stock under all employee stock purchase plans (described in Section 423 of the Code) of the Company and its Subsidiaries to accrue at a rate that exceeds $25,000 of the Fair Market Value of such stock (determined at the time the option is granted) for each calendar year in which such option is outstanding at any time.

5. Offering Periods. The Plan shall be implemented by a series of Offering Periods. Unless otherwise provided by the Committee, Offering Periods shall be periods of approximately six (6) months during which an option granted pursuant to the Plan may be exercised, commencing on the first Trading Day on or after February 16 and August 16 of each year and terminating on the first Trading Day on or after August 15 and February 15, approximately six (6) months later. The Committee shall have the authority to change the duration, frequency, start and end dates of future Offering Periods (up to a maximum Offering Period of 27 months).

6. Participation.

6.1 Enrollment; Payroll Deductions. An Eligible Employee may elect to participate in the Plan by properly completing an Enrollment Form, which may be electronic, and submitting it to the Company in accordance with the enrollment procedures established by the Committee. Participation in the Plan is entirely voluntary. By submitting an Enrollment Form, the Eligible Employee authorizes payroll deductions from his or her paycheck in an amount equal to at least $200 per month, but not more than $2,000 per month, during an Offering Period (or such other maximum percentage as the Committee may establish from time to time before an Offering Period begins), subject to the limitations set forth in Section 4. If the Eligible Employee contributes an amount that exceeds the limitations set forth in Section 4, the excess amount shall be returned to the Eligible Employee in the next administratively feasible payroll following the applicable Offering Period. Payroll

deductions shall commence on the first payroll date following the Offering Date and end on the last payroll date on or before the Purchase Date. The Company shall maintain records of all payroll deductions but shall have no obligation to pay interest on payroll deductions or to hold such amounts in a trust or in any segregated account. Unless expressly permitted by the Committee in writing, a Participant may not make any separate contributions or payments to the Plan.

6.2 Election Changes. During an Offering Period, a Participant may not change the rate of his or her payroll deductions applicable to such Offering Period. A Participant may decrease or increase his or her rate of payroll deductions for future Offering Periods by submitting a new Enrollment Form authorizing the new rate of payroll deductions at least fifteen days before the start of the next Offering Period. However, a Participant may withdraw from the Plan in accordance with Section 9.

6.3 Automatic Re-enrollment. The deduction rate selected in the Enrollment Form shall remain in effect for subsequent Offering Periods unless the Participant (a) submits a new Enrollment Form authorizing a new level of payroll deductions in accordance with Section 6.2, (b) withdraws from the Plan in accordance with Section 9, or (c) terminates employment or otherwise becomes ineligible to participate in the Plan.

6.4 Grant of Option. On each Offering Date, each Participant in the applicable Offering Period shall be granted an option to purchase, on the Purchase Date, a number of shares of Common Stock determined by dividing the Participant’s accumulated payroll deductions by the applicable Purchase Price; provided, however, that in no event shall any Participant purchase more than 150 shares of Common Stock per Offering Period. The Committee may, for future Offering Periods, increase or decrease, in its absolute discretion, the maximum number of shares of Common Stock that an Eligible Employee may purchase during Offering Period.

7. Exercise of Option/Purchase of Shares. A Participant’s option to purchase shares of Common Stock will be exercised automatically on the Purchase Date of each Offering Period. The Participant’s accumulated payroll deductions will be used to purchase the maximum number of whole shares that can be purchased with the amounts in the Participant’s notional account. If and to the extent provided by the Committee, for so long as such shares of Common Stock are maintained in ESPP Share Accounts, all dividends paid with respect to such shares of Common Stock shall be paid in cash. No fractional shares may be purchased. Any amount remaining in the Participant’s notional account as of the Purchase Date in excess of the amount that may be applied to purchase shares shall be carried over to the next Offering Period, subject to earlier withdrawal by the Participant in accordance with Section 9 or termination of employment in accordance with Section 10.

8. Transfer of Shares. As soon as reasonably practicable after each Purchase Date, the Company will arrange for the delivery to each Participant of the shares of Common Stock purchased upon exercise of his or her option. The Committee may permit or require that the shares be deposited directly into an ESPP Share Account established in the name of the Participant with a Designated Broker. Participants will not have any voting, dividend or other rights of a stockholder with respect to the shares of Common Stock subject to any option granted hereunder until such shares have been delivered pursuant to this Section 8.

9. Withdrawal.

9.1 Withdrawal Procedure. A Participant may withdraw from an Offering by submitting to the Company a revised Enrollment Form indicating his or her election to withdraw at least thirty days before the end of the Offering Period. The accumulated payroll deductions held on behalf of a Participant in his or her notional account (that have not been used to purchase shares of Common Stock) shall be paid without interest to the Participant in the next administratively feasible payroll following receipt of the Participant’s Enrollment Form indicating his or her election to withdraw and the Participant’s option shall be automatically terminated. If a Participant withdraws from an Offering Period, no payroll deductions will be made during any succeeding Offering Period, unless the Participant re-enrolls in accordance with Section 6.1 of the Plan.

9.2 Effect on Succeeding Offering Periods. A Participant’s election to withdraw from an Offering Period will not have any effect upon his or her eligibility to participate in succeeding Offering Periods that commence following the completion of the Offering Period from which the Participant withdraws; provided however, the Committee may impose restrictions upon a Participant’s ability to withdraw from an Offering Period and re-enroll in succeeding Offering Periods.

10. Termination of Employment; Change in Employment Status. Upon termination of a Participant’s employment for any reason, including death, disability or retirement, or a change in the Participant’s employment status following which the Participant is no longer an Eligible Employee, which in either case occurs before the Purchase Date, the Participant will be deemed to have withdrawn from the Plan and the payroll deductions in the Participant’s notional account (that have not been used to purchase shares of Common Stock) shall be returned to the Participant, or in the case of the Participant’s death, to the person(s) entitled to such amounts under Section 16, and the Participant’s option shall be automatically terminated. If at any time within one (1) year after the Purchase Date and after termination of a Participant’s employment for any reason, the Committee determines in its discretion either that, (1) during the Participant’s period of employment, the Participant engaged in an act or omission which would have warranted termination for Cause or (2) after a Participant’s termination of employment, the Participant engaged in conduct that violated any continuing obligation or duty of the Participant in respect of the Company or a Participating Subsidiary, then, at the sole discretion of the Committee, the Clawback Discount Value shall be repaid by the Participant to the Company upon notice from the Company, subject to applicable law.

11. Interest. No interest shall accrue on or be payable with respect to the payroll deductions of a Participant in the Plan.

12. Shares Reserved for Plan.

12.1 Number of Shares. Subject to adjustments as described below, a total of 121,221 shares of Common Stock have been reserved for issuance under the Plan.

12.2 Over-subscribed Offerings. The number of shares of Common Stock which a Participant may purchase in an Offering under the Plan may be reduced if the Offering is over-subscribed. No option granted under the Plan shall permit a Participant to purchase shares of Common Stock which, if added together with the total number of shares of Common Stock purchased by all other Participants in such Offering would exceed the total number of shares of Common Stock remaining available under the Plan. If the Committee determines that, on a particular Purchase Date, the number of shares of Common Stock with respect to which options are to be exercised exceeds the number of shares of Common Stock then available under the Plan, the Company shall make a pro rata allocation of the shares of Common Stock remaining available for purchase in as uniform a manner as practicable and as the Committee determines to be equitable.

13. Transferability. No payroll deductions credited to a Participant, nor any rights with respect to the exercise of an option or any rights to receive Common Stock hereunder may be assigned, transferred, pledged or otherwise disposed of in any way (other than by will, the laws of descent and distribution, or as provided in Section 16 hereof) by the Participant. Any attempt to assign, transfer, pledge or otherwise dispose of such rights or amounts shall be without effect.

14. Application of Funds. All payroll deductions received or held by the Company under the Plan may be used by the Company for any corporate purpose to the extent permitted by applicable law, and the Company shall not be required to segregate such payroll deductions or contributions.

15. Statements. Participants will be provided with and/or have access to statements at least annually which shall set forth the contributions made by the Participant to the Plan, the Purchase Price of any shares of Common Stock purchased with accumulated funds, the number of shares of Common Stock purchased, and any payroll deduction amounts remaining in the Participant’s notional account.

16. Designation of Beneficiary. A Participant may file, on forms supplied by the Designated Broker, a written designation of beneficiary who is to receive any shares of Common Stock, from the Participant’s ESPP Share Account under the Plan in the event of such Participant’s death. In addition, a Participant may file a written designation of beneficiary who is to receive any cash withheld through payroll deductions and credited to the Participant’s notional account in the event of the Participant’s death prior to the Purchase Date of an Offering Period. In the event that no such form or designation is filed, the shares of Common Stock or cash shall be distributed to the Participant’s estate.

17. Adjustments.

17.1 Adjustments. If there shall occur any change with respect to the outstanding shares of Common Stock by reason of any recapitalization, reclassification, stock dividend, extraordinary dividend, stock split, reverse stock split or other distribution with respect to the shares of Common Stock or any merger, reorganization, consolidation, combination, spin-off or other similar corporate change or any other change affecting the Common Stock (other than regular cash dividends to stockholders of the Company), then in order to prevent dilution or enlargement of the benefits or potential benefits intended to be made available under the Plan, the Committee will, in such manner as it deems equitable and subject to stockholder approval if required to comply with Section 423 of the Code, adjust the number and kind of shares of stock that may be delivered under the Plan, the Purchase Price per share and the number of shares of Common Stock covered by each outstanding option under the Plan, and the numerical limits of Section 6.4 and Section 12.

17.2 Change in Control. In the event of a Change in Control, the Committee shall have the power and discretion to (i) continue the Offering Period in effect on the date of such Change in Control, (ii) shorten the Offering Period then in progress by setting a “New Purchase Date” which shall be before the date of the Company’s proposed Change in Control, (iii) substitute shares of Common Stock available under the Plan with shares of common stock of the surviving company or its parent, or (iv) terminate the Plan and return any payroll deductions in the Participant’s notional account (that have not been used to purchase shares of Common Stock) to the Participant. In the event of prong (ii), the Committee shall notify each Participant in writing, at least ten (10) trading days prior to the New Purchase Date, that the Purchase Date for the Participant’s purchase right has been changed to the New Purchase Date and that shares of Common Stock shall be purchased automatically on the New Purchase Date, unless prior to such date the Participant has withdrawn from the Offering Period as describe in Section 9 above.

18. General Provisions.

18.1 Equal Rights and Privileges. Notwithstanding any provision of the Plan to the contrary and in accordance with Section 423 of the Code, all Eligible Employees who are granted options under the Plan shall have the same rights and privileges.

18.2 No Right to Continued Service. Neither the Plan nor any compensation paid hereunder will confer on any Participant the right to continue as an Employee or in any other capacity.

18.3 Rights As Stockholder. A Participant will become a stockholder with respect to the shares of Common Stock that are purchased pursuant to options granted under the Plan when the shares are transferred to the Participant or the Participant’s ESPP Share Account. A Participant will have no rights as a stockholder with respect to shares of Common Stock for which an election to participate in an Offering Period has been made until such Participant becomes a stockholder as provided above.

18.4 Successors and Assigns. The Plan shall be binding on the Company and its successors and assigns.

18.5 Entire Plan. This Plan constitutes the entire plan with respect to the subject matter hereof and supersedes all prior plans with respect to the subject matter hereof.

18.6 Compliance With Law. The obligations of the Company with respect to payments under the Plan are subject to compliance with all applicable laws and regulations. Common Stock shall not be issued with respect to an option granted under the Plan unless the exercise of such option and the issuance and delivery of the shares of Common Stock pursuant thereto shall comply with all applicable provisions of law, including, without limitation, the Securities Act, the Exchange Act, and the requirements of any stock exchange upon which the shares may then be listed.

18.7 Term of Plan. The Plan shall become effective on the Effective Date and shall remain in full force and effect until terminated pursuant to Section 18.8.

18.8 Amendment or Termination. The Committee may, in its sole discretion, amend, suspend or terminate the Plan at any time and for any reason. If the Plan is terminated, the Committee may elect to terminate all outstanding Offering Periods either immediately or once shares of Common Stock have been purchased on the next Purchase Date (which may, in the discretion of the Committee, be accelerated) or permit Offering Periods to expire in accordance with their terms (and subject to any adjustment in accordance with Section 17). If any Offering Period is terminated before its scheduled expiration, all amounts that have not been used to purchase shares of Common Stock will be returned to Participants (without interest, except as otherwise required by law) as soon as administratively practicable.

18.9 Applicable Law. The Plan and all rights hereunder shall be subject to and interpreted in accordance with the laws of the State of Delaware, without reference to the principles of conflicts of laws, and to applicable Federal or other securities laws.

18.10 Stockholder Approval. The Plan shall be subject to approval by the stockholders of the Company within twelve (12) months before or after the date the Plan is adopted by the Board.

18.11 Section 423. The Plan is intended to qualify as an “employee stock purchase plan” under Section 423 of the Code. Any provision of the Plan that is inconsistent with Section 423 of the Code shall be reformed to comply with Section 423 of the Code.

18.12 Withholding. To the extent required by applicable Federal, state or local law, a Participant must make arrangements satisfactory to the Company for the payment of any withholding or similar tax obligations that arise in connection with the Plan.

18.13 Severability. If any provision of the Plan shall be determined to be illegal or unenforceable by any court of law in any jurisdiction, the remaining provisions hereof and thereof shall be severable and enforceable in accordance with their terms, and all provisions shall remain enforceable in any other jurisdiction.

18.14 Headings. The headings of sections herein are included solely for convenience and shall not affect the meaning of any of the provisions of the Plan.