Letter Agreement, effective July 1, 2019, between Marsh & McLennan Companies, Inc. and Dominic J. Burke

Annual Base Salary: You will receive an annual base salary of the amount set forth on Exhibit A, payable in installments in accordance with Marsh’s or the Company’s payroll procedures in effect from time to time. Your base salary includes compensation for all time worked, as well as appropriate consideration for sick days, personal days, and other time off in accordance with Marsh and relevant Company policies. Your base salary will be considered for adjustment in succeeding years as part of the Company’s normal senior performance management process.

Vacation: In addition to the U.K. bank and public holidays that are observed in accordance with Company policy, you are entitled to 40 working days of vacation annually, which will be administered in accordance with Company policy, at times that are agreed in advance. You will, if requested, take any accrued vacation during any period of notice to terminate your employment.

Annual Bonus: You are eligible for an annual bonus on the terms set forth on Exhibit A. Bonus awards are discretionary and will be paid in cash. Except as provided in this paragraph and in Section 3(a), to qualify for an annual bonus, you must remain continuously and actively employed by the Company, without having tendered or been given notice of termination, through the date of the bonus payment, in accordance with the terms and conditions of the award. The annual bonus shall be paid no later than March 15 of the year following the year for which such bonus is earned. In the event of your Permanent Disability (as defined below) or death, the Company shall pay you (or your estate in the case of death) a prorated target annual bonus for the year in which your termination occurs based on the portion of the year elapsed as of the date of your termination. Any such bonus amount shall be paid within 30 days of your death. In the event of your Permanent Disability, your prorated annual bonus payment is conditioned upon, and subject to, your execution and delivery to the Company within 30 days of the date of such event a valid confidential waiver and release of claims agreement (including restrictive covenants) in a form satisfactory to the Company (the “Release”) and such Release has become irrevocable as provided therein (the “Release Effective Date”). Payment of any such annual bonus amount shall then be paid within 30 days following the Release Effective Date, but in no event later than March 15 of the year following the year for which such bonus is earned.

Annual Long-Term Incentive Compensation: You are eligible to participate in Marsh & McLennan Companies’ long-term incentive program with a target long-term incentive compensation award as set forth on Exhibit A. Long-term incentive awards are discretionary and are governed by terms and conditions approved by the Compensation Committee of the Marsh & McLennan Companies Board of Directors (“Compensation Committee”) as set forth in the award agreement and in Marsh & McLennan Companies’ 2011 Incentive and Stock Award Plan (or other plan under which the long-term incentive award is granted). In accordance with Company practice, you may be required to enter into a “Restrictive Covenants Agreement” in connection with long-term incentive awards.

Special Restricted Stock Unit Award: On the first calendar day of the month following the closing of the acquisition of Jardine, Lloyd Thompson Group, plc (“JLT”) by the Company (the “Acquisition”), you will be granted an award of restricted stock units (“RSUs") as set forth on Exhibit A in lieu of any JLT Deferred Bonus Scheme award. Your award will be converted from the dollar value of the grant into RSUs based upon the average of the high and low sales prices of a share of Marsh & McLennan Companies common stock on the New York Stock Exchange one trading day prior to the effective date of the grant. One third of the RSUs will vest on each of the first three anniversaries of the grant date, subject to your continued employment, will fully vest in the event the Company terminates your employment without cause and will be subject to terms and conditions approved by the Compensation Committee as set forth in the award agreement and in Marsh & McLennan Companies’ 2011 Incentive and Stock Award Plan (or any successor plan under which the award is granted). You will receive additional information regarding these RSUs, including the terms and conditions of the award, shortly after the award is granted.

Annual Retention Awards. You will be eligible for three annual retention awards (each, an “Annual Retention Award”) as set forth herein and in the amount on Exhibit A. On each of the first three anniversaries of the Acquisition, provided that you remain continuously and actively employed by the Company, with neither the Company nor you having tendered notice of termination of employment, an Annual Retention Award will vest and be paid within 30 days after such anniversary. In the event the Company provides you notice of your termination of employment without cause (as defined in the Senior Executive Severance Plan) prior to the third anniversary of the Acquisition, the Company will pay you the Annual Retention Award that is scheduled to vest on the next anniversary of the Acquisition, conditioned on, and subject to, your execution and delivery to the Company within 30 days following the date of your termination of employment a Release and such Release has become irrevocable as provided therein. Any such Annual Retention Award shall be paid within 30 days following such Release Effective Date, and you will not be eligible for any further Annual Retention Awards. In the event you provide notice of your termination of employment, or your employment terminates for any reason other than a termination of employment by the Company without cause, any unpaid Annual Retention Award will be forfeited and you will not be eligible for any further Annual Retention Awards.

Benefit Programs: You and your eligible family members will have the opportunity to participate in the employee benefit plans, policies and programs provided by Marsh & McLennan Companies, on such terms and conditions as are generally provided to similarly

You have been designated as a “Key Employee” under the Marsh & McLennan Companies, Inc. Senior Executive Severance Pay Plan (the “Senior Executive Severance Plan”). In the event that your employment with the Company terminates for any reason, the Senior Executive Severance Plan in effect at the time of your termination will exclusively govern the terms under which you may be eligible to receive severance and/or other transition benefits from the Company; provided that any payments to which you may be entitled under the Senior Executive Severance Plan will be made within 60 days after the date of your termination of employment (as determined under Section 8(i) below). For the avoidance of doubt, any entitlement to severance payments under Article 5 of the Senior Executive Severance Plan shall be reduced by any amounts you receive pursuant to Sections 3(b) and 3(d) below. If you are entitled to receive severance benefits under Article 5 of the Senior Executive Severance Plan, the Company shall also pay you the earned annual bonus, if any, for the calendar year that preceded your termination to the extent not theretofore paid.

The Company may on its own behalf and on behalf of Marsh terminate your employment at any time by giving you twelve months’ notice in writing, or by making you a payment of base salary in lieu of notice within 60 days after your termination of employment (subject to Section 8(i) below). Your employment may however be terminated for cause (as defined in the Senior Executive Severance Plan) immediately without notice or payment in lieu. You may terminate your employment by giving the Company twelve months’ written notice of termination.

In the event you provide notice to the Company of your termination of employment after the first anniversary of the Acquisition and before the third anniversary of the Acquisition, your termination of employment will be treated as a termination by the Company without cause exclusively for purposes of your outstanding equity-based awards and the Senior Executive Severance Plan (with payments thereunder made in accordance with Section 3(a)). For the avoidance of doubt, this provision shall not apply to the Annual Retention Awards described in Section 2(f).

At any time during any period of notice of termination, you may be suspended on full pay and benefits, and the Company shall be under no obligation to provide you any work or to assign you any duties. You acknowledge and agree that you may during such period of paid suspension be excluded from Company premises, removed from directorships and required to refrain from business contact with clients, officers, agents or employees of the Company.

Upon the termination of your employment for any reason, you shall immediately resign, as of your date of termination, from all positions that you then hold with any member of the Affiliated Group, and return to Marsh all Company property, materials and documents (whether held in hard or soft copy) then in your possession or under your control. You hereby agree to execute any and all documentation to effectuate such resignations upon request by the Company, but you shall be treated for all purposes as having so resigned upon your date of termination, regardless of when or whether you execute any such documentation.

During the term of this letter agreement, and, subject to any other business obligations that you may have, following your date of termination, you agree to assist the Affiliated Group in the investigation and/or defense of any claims or potential claims that may be made or threatened to be made against any member of the Affiliated Group, including any of their officers or directors (a “Proceeding”), and will assist the Affiliated Group in connection with any claims that may be made by any member of the Affiliated Group in any Proceeding. You agree, unless precluded by law, to promptly inform Marsh & McLennan Companies if you are asked to participate in any Proceeding or to assist in any investigation of any member of the Affiliated Group. In addition, you agree to provide such services as are reasonably requested by the Company to assist any successor to you in the transition of duties and responsibilities to such successor. Following the receipt of reasonable documentation, the Company agrees to reimburse you for all of your reasonable out-of-pocket expenses associated with such assistance. Your request for any reimbursement, including reasonable documentation, must be submitted as soon as practicable and otherwise consistent with Company policy. In any event, your request for a taxable reimbursement, including reasonable documentation, must be submitted by the October 31st of the year following the year in which the expense is incurred. The Company will generally reimburse such expenses within 60 days of the date they are submitted, but in no event will they be reimbursed later than the December 31st of the year following the year in which the expense is incurred.