MARKETAXESS SEVERANCE PAY PLAN

Exhibit 10.28(a )

MARKETAXESS SEVERANCE PAY PLAN

Effective August 1, 2006

Exhibit 10.28(a)

TABLE OF CONTENTS

Exhibit 10.28(a)

MARKETAXESS SEVERANCE PAY PLAN
(for MarketAxess Holdings, Inc. and participating affiliates)

ARTICLE I — INTRODUCTION

     MarketAxess Holdings, Inc. (the “Company”) hereby establishes the MarketAxess Severance Pay Plan (the “Plan”), effective as of August 1, 2006, to provide severance benefits to certain employees of the Company and its participating affiliates who suffer a loss of employment under the terms and conditions set forth in the Plan. The Plan replaces and supersedes any and all severance plans, policies and/or practices of the Company and its participating affiliates in effect for covered employees prior to August 1, 2006. The Plan is intended to fall within the definition of an “employee welfare benefit plan” under Section 3(1) of the Employee Retirement Income Security Act of 1974, as amended. No employee or representative of the Company, the Employers or any of their affiliates is authorized to modify, add to or subtract from these terms and conditions, except in accordance with the amendment and termination procedures described herein.

ARTICLE II — DEFINITIONS AND INTERPRETATIONS

     The following definitions and interpretations of important terms apply to the Plan.

     1.  Agreement and General Release . The release executed by an Employee (in a form acceptable to the Plan Administrator, in its sole and absolute discretion) under which, among other things, the Employee releases and discharges all Employers and related entities (as well as any third party for whom the employee provides services on the Employer’s behalf) from all claims and liabilities relating to the Employee’s employment with the Employer and/or the termination of the Employee’s employment, including without limitation, claims under the Title VII of the Civil Rights Act of 1964, the Americans with Disabilities Act, the Family and Medical Leave Act, the Age Discrimination in Employment Act, the Older Workers Benefit Protection Act, where applicable, the California Fair Employment and Housing Act, the California Labor Code Sections 200 et seq., 510 et seq., 970 and 1959 et seq., defamation provisions of California Civil Code Section 44 et seq., and the New York State and City Human Rights Laws (and similar laws of any other state).

     2.  Cause . Any one of the following reasons for the discharge or other separation of an Employee from employment with the Employer:

          (i) any act or omission by the Employee resulting or intended to result in personal gain at the expense of the Employer;

          (ii) misconduct by the Employee, including, but not limited to insubordination, dishonesty, fraud, incompetence, moral turpitude, willful misconduct, failure to abide by the Employers’ policies, rules or procedures, theft, violent acts or threats of violent acts, unauthorized possession of alcohol or controlled substances on an Employer’s property, use of the Employer’s property, facilities or services for unauthorized or illegal purposes, or refusal to perform his or her duties or responsibilities for any reason other than illness or incapacity;

          (iii) performance of duties for the Employer in a manner deemed by the Employer as materially unsatisfactory;

          (iv) in the case where there is an employment agreement, change in control agreement or similar agreement in effect between the Employee and the Employer that defines “cause” (or words of like import), “cause” as defined under such agreement; provided, however, that with regard to any agreement under which the definition of “cause” only applies on occurrence of a change in control, such definition of “cause” shall not apply until a change in control actually takes place and then only with regard to a termination thereafter; or

          (iv) the improper disclosure by the Employee of proprietary or confidential information or trade secrets of the Employer, or intellectual property that the Employer is under a duty to protect (including software licensed to the Employer under agreements prohibiting disclosure).

If an Employee is terminated from employment and it is subsequently determined that, by virtue of conduct or circumstances, arising either before or after the termination, the Employee or former Employee engaged in what would have constituted Cause, the termination will be deemed to have been for Cause, and the individual will be ineligible for benefits under the Plan. In such circumstances, in the event that Plan benefits have already been paid by the Employer, the Employer shall be entitled to recover any such benefits.

     3.  Company . MarketAxess Holdings, Inc.

     4.  Effective Date . August 1, 2006.

     5.  Employee . Any active, regular, U.S.-based employee of an Employer and on the Employer’s payroll other than an employee whose terms and conditions of employment are covered by a collective bargaining agreement that does not provide for participation in the Plan or an employee who is party to a formal or informal written employment agreement with an Employer that either provides for severance or other payments in the event of the individual’s termination of employment or any other separation from service with the Employer or states that no such payments will be made in that event. Notwithstanding the preceding sentence, “Employee” also does not include any

individual (i) designated by the Employer as an independent contractor and not as an employee at the time of any determination, (ii) being paid by or through a third party agency, (iii) designated by the Employer as a freelance worker and not as an employee at the time of any determination, (iv) designated by the Employer as an intern, summer intern or consultant, (v) designated by the Employer as a seasonal, occasional, limited duration, leased or temporary employee, during the period the individual is so paid or designated; any such individual shall not be an Employee even if he or she is later retroactively reclassified as a common-law or other type of employee of the Employer during all or any part of such period pursuant to applicable law or otherwise.

     6.  Employer . The Company and each affiliate or subsidiary of the Company that participates in the Plan. As of August 1, 2006, the Employers are the Company and MarketAxess Corporation.

     7.  Participant . An Employee who meets the requirements for eligibility under the Plan, as set forth in Article III of the Plan. An individual shall cease being a Participant once all severance due to such individual under the Plan has been paid (or, if earlier, upon the death of the Participant) and no person shall have any further rights under this Plan with respect to such former Participant.

     8.  Plan Administrator . The Company including such other person or committee appointed from time to time by the Company to administer the Plan. Until a successor is appointed by the Company, except as otherwise indicated herein, the Head of Human Resources of MarketAxess Corporation has been designated by the Company to act on behalf of the Plan Administrator with day-to-day matters regarding the Plan.

     9.  Termination Date . The date designated by the Employer for each eligible Employee on which such Employee will experience a Termination of Employment with such Employer. Notwithstanding the foregoing, with respect to any eligible Employee, the Employer reserves the right, in its sole and absolute discretion, to change a previously designated Termination Date.

     10.  Termination of Employment .

     A. The termination by an Employer of an Employee’s employment relationship with the Employer as the result of a job elimination, job discontinuation, office closing, staff reduction, organizational restructuring, or unsatisfactory performance that does not constitute Cause.

     B. Notwithstanding the preceding paragraph, a Termination of Employment does not include a discharge or other separation of employment under any of the following circumstances:

          (i) for Cause;

          (ii) an Employee’s retirement, voluntary resignation or job abandonment (including, without limitation, the termination of employment for excess absenteeism);

          (iii) an Employee’s death or disability; or

          (iv) the business or a portion of the business of an Employer is (i) sold in whole or in part to another corporation, company or individual, whether by sale of stock or assets, (ii) merged or consolidated with another corporation, company or individual or is part of a similar corporate transaction or (iii) outsourced to another corporation, company or individual, and the Employee is offered employment with the purchaser or surviving business or the corporation, company or individual to which the business is outsourced (whether or not he or she accepts any such position with the purchaser, surviving business or other company or individual) in a position (a) providing a rate of compensation of at least 80% of the Employee’s compensation immediately prior to the occurrence and (b) within 30 miles of the Employee’s current primary worksite.

     The determination as to whether a discharge or other separation from service is for Cause or is otherwise described in this Section will be made by the Plan Administrator, in its sole and absolute discretion, and such determination shall be final and binding on all affected Employees. An Employee’s Termination of Employment shall occur on the last day of his or her employment with the Employer.

     11.  Week of Base Pay . The Employee’s weekly base salary (prior to tax withholding) at the time of his or her Termination Date, excluding bonuses, overtime pay, commissions, non-cash compensation, employer contributions to employee benefit plans, incentive or deferred compensation or any other additional compensation. However, it will include salary reduction contributions made on an Employee’s behalf to any plan of the Employer under Section 125, 132(f) or 401(k) of the Internal Revenue Code of 1986, as amended. A Week of Base Pay for a part-time Employee shall mean the average weekly pay for the six-month period of payroll immediately preceding the Employee’s Termination Date (with the same inclusions as for full-time Employees).

     12.  Years of Service . As of the Employee’s Termination Date, the number of consecutive full twelve (12) month periods since the Employee’s last date of hire by the Employer in which the Employee is paid by the Employer for the performance of services in a capacity that qualifies such person as an Employee. Years of Service shall be measured in full years and no credit shall be provided for fractions of a Year of Service, except that a partial year of service of at least eleven (11) months shall be rounded up to a full year. In addition, an Employee who has not completed at least one Year of Service shall be credited with 6 Months of Service if, as of the Employee’s Termination Date,

the Employee has completed a consecutive full six-month period since the Employee’s last date of hire by the Employer in which the Employee is paid by the Employer for the performance of services in a capacity that qualifies such person as an Employee.

ARTICLE III — ELIGIBILITY TO PARTICIPATE

     An Employee becomes a Participant in the Plan and shall be entitled to severance benefits only if he or she:

(i) Is notified of his/her Termination of Employment, to be effective as of his or her Termination Date;

(ii) Remains in the continuous employ of an Employer until his or her Termination Date, does not voluntarily terminate employment and is not involuntarily terminated by the Employer for Cause;

(iii) Experiences a Termination of Employment; and

(iv) Ti