EMPLOYMENT AGREEMENT This Employment Agreement ( Agreement ) is made by and between Magenta Therapeutics, Inc., a Delaware corporation (the Company ), and Jason Ryan (the Executive ), and is effective as of the first dat

EMPLOYMENT AGREEMENT

This Employment Agreement ( Agreement ) is made by and between Magenta Therapeutics, Inc., a Delaware corporation (the

Company ), and Jason Ryan (the Executive ), and is effective as of the first date of the Executive s employment with the Company (the Effective Date ). Except with respect to the Restrictive Covenant Agreement

and the Equity Documents (each as defined below), this Agreement supersedes, amends and restates in all respects all prior agreements between the Executive and the Company regarding the subject matter herein, including without limitation any offer

letter, employment agreement or severance agreement.

WHEREAS, the Company desires to employ the Executive and the Executive desires to be

employed by the Company on the terms contained herein.

NOW, THEREFORE, in consideration of the mutual covenants and agreements herein

contained and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties agree as follows:

Term. The Company and the Executive desire that their employment relationship be subject to this Agreement commencing as of the Effective Date and continuing in effect until terminated by either party in accordance with this Agreement (the

Term ). The Executive s employment with the Company will continue to be at will, meaning that the Executive s employment may be terminated by the Company or the Executive at any time and for any reason subject to the

terms of this Agreement.

b) Position and Duties. During the Term, the Executive shall serve as the Chief Operating and Financial

Officer of the Company, and shall have powers and duties that may from time to time be prescribed by the Company s Chief Executive Officer (the CEO ) or another authorized executive. The Executive shall devote his full working time

and efforts to the business and affairs of the Company. Notwithstanding the foregoing, the Executive may serve on up to two other boards of directors, with the prior written approval of the Board of Directors of the Company (the Board ).

Further, the Executive may engage in religious, charitable or other community activities as long as such services and activities are disclosed to the Board and do not interfere with the Executive s performance of his duties to the Company as

provided in this Agreement. The Executive reaffirms that he has no contractual commitments or other legal obligations that would prohibit him from fully performing his duties for the Company.

2. Compensation and Related Matters.

a) Base Salary. The Executive s annual base salary shall be $400,000.00, which is subject to review and redetermination by the

Compensation Committee. The base salary in effect at any given time is referred to herein as Base Salary. The Base Salary shall be payable in a manner that is consistent with the Company s usual payroll practices for senior

b) Incentive Compensation. During the Term, the Executive shall be eligible to

receive cash incentive compensation as determined by the Board or the Compensation Committee from time to time. The Executive s target annual incentive compensation shall be 40 percent of his Base Salary, as may be redetermined from time

to time (the Target Incentive Compensation ). To earn incentive compensation, the Executive must be employed by the Company on the day such incentive compensation is paid.

c) Expenses. The Executive shall be entitled to receive prompt reimbursement for all reasonable expenses incurred by him during the Term

in performing services hereunder, in accordance with the policies and procedures then in effect and established by the Company for its senior executive officers.

d) Other Benefits. During the Term, the Executive shall be entitled to continue to participate in or receive benefits under the

Company s employee benefit plans in effect from time to time, including paid sick time under applicable law, subject to the terms of such plans and to the Company s ability to amend, modify, replace or terminate such plans and programs.

e) Vacations. During the Term, the Executive shall be entitled to accrue up to 20 paid vacation days in each calendar year, except

for calendar year 2019, where the Executive will accrue up to 25 paid vacation days. Vacation days shall be accrued ratably and must be used in accordance with the Company s vacation policy. The Executive shall also be entitled to all paid

holidays given by the Company to its executives.

f) Equity. The equity awards held by the Executive shall be governed by the terms

and conditions of the Company s applicable equity incentive plan(s) and the applicable award agreement(s) governing the terms of such equity awards held by the Executive (collectively, the Equity Documents ); provided, however, and

notwithstanding anything to the contrary in the Equity Documents, Section 6(a)(ii) of this Agreement shall apply in the event of a termination by the Company without Cause or by the Executive for Good Reason in either event within the Change in

Control Period (as such terms are defined below).

g) Sign-On Bonus. The Company shall pay

the Executive a one-time sign-on bonus of $25,000, less applicable deductions and withholdings (the Sign-On Bonus ),

to be paid within thirty (30) days after the Effective Date. The Executive agrees that if he terminates his employment for any reason or if the Company terminates his employment with Cause (as defined below), in each case prior to the one year

anniversary of the Effective Date, he will repay the entire Sign-On Bonus within 30 days of the Date of Termination (as defined below).

3. Termination. During the Term, the Executive s employment hereunder may be terminated without any breach of this Agreement under

the following circumstances:

a) Death. The Executive s employment hereunder shall terminate upon his death.

b) Disability. The Company may terminate the Executive s employment if he is

disabled and unable to perform the essential functions of the Executive s then existing position or positions under this Agreement with or without reasonable accommodation for a period of 180 days (which need not be consecutive) in any 12-month period. If any question shall arise as to whether during any period the Executive is disabled so as to be unable to perform the essential functions of the Executive s then existing position or

positions with or without reasonable accommodation, the Executive may, and at the request of the Company shall, submit to the Company a certification in reasonable detail by a physician selected by the Company to whom the Executive or the

Executive s guardian has no reasonable objection as to whether the Executive is so disabled or how long such disability is expected to continue, and such certification shall for the purposes of this Agreement be conclusive of the

issue. The Executive shall cooperate with any reasonable request of the physician in connection with such certification. If such question shall arise and the Executive shall fail to submit such certification, the Company s determination of such

issue shall be binding on the Executive. Nothing in this Section 3(b) shall be construed to waive the Executive s rights, if any, under existing law including, without limitation, the Family and Medical Leave Act of 1993, 29 U.S.C.

2601 et seq, and the Americans with Disabilities Act, 42 U.S.C. 12101 et seq.

c) Termination by Company for

Cause. The Company may terminate the Executive s employment hereunder for Cause. For purposes of this Agreement, Cause shall mean: (i) the Executive s dishonest statements or acts with respect to the Company or any

affiliate of the Company, or any current or prospective customers, suppliers vendors or other third parties with which such entity does business; (ii) the Executive s commission of (A) a felony or (B) any misdemeanor involving

moral turpitude, deceit, dishonesty or fraud; (iii) the Executive s failure to perform his assigned duties and responsibilities to the reasonable satisfaction of the Company which failure continues, in the reasonable judgment of the

Company, for thirty (30) days after written notice given to the Executive by the Company; (iv) the Executive s gross negligence, willful misconduct or insubordination with respect to the Company or any affiliate of the Company; or

(v) the Executive s material violation of any provision of any agreement(s) between the Executive and the Company relating to noncompetition, nonsolicitation, nondisclosure and/or assignment of inventions.

d) Termination without Cause. The Company may terminate the Executive s employment hereunder at any time without Cause. Any

termination by the Company of the Executive s employment under this Agreement which does not constitute a termination for Cause under Section 3(c) and does not result from the death or disability of the Executive under Section 3(a) or

(b) shall be deemed a termination without Cause.

e) Termination by the Executive. The Executive may terminate his employment

hereunder at any time for any reason, including but not limited to Good Reason. For purposes of this Agreement, Good Reason shall mean that the Executive has complied with the Good Reason Process (hereinafter defined)

following the occurrence of any of the following events: (i) a material diminution in the Executive s responsibilities, authority or duties; (ii) a material diminution in the Executive s Base Salary except for across-the-board salary reductions based on the Company s financial performance similarly affecting all or substantially all senior management employees of the Company;

(iii) a material change in the geographic location, which would be a move of greater than 25 miles from the current location (judging from a straight line projecting out from the current home office to form the radius of a circle around the

current location), at which the Executive provides services to the Company; or (iv) the material breach of this Agreement by the Company. Good Reason Process shall mean that

(i) the Executive reasonably determines in good faith that a Good Reason condition has occurred; (ii) the Executive notifies the Company in writing of the first occurrence of the

Good Reason condition within 60 days of the first occurrence of such condition; (iii) the Executive cooperates in good faith with the Company s efforts, for a period not less than 30 days following such notice (the Cure

Period ), to remedy the condition; (iv) notwithstanding such efforts, the Good Reason condition continues to exist; and (v) the Executive terminates his employment within 60 days after the end of the Cure Period. If the Company cures

the Good Reason condition during the Cure Period, Good Reason shall be deemed not to have occurred.

If the Executive s employment with the Company

is terminated for any reason, the Company shall pay or provide to the Executive (or to his authorized representative or estate) (i) any Base Salary earned through the Date of Termination, unpaid expense reimbursements (subject to, and in

accordance with, Section 2(c) of this Agreement) and unused vacation that accrued through the Date of Termination on or before the time required by law but in no event more than 30 days after the Executive s Date of Termination; and

(ii) any vested benefits the Executive may have under any employee benefit plan of the Company through the Date of Termination, which vested benefits shall be paid and/or provided in accordance with the terms of such employee benefit plans

(collectively, the Accrued Benefit ).

4. Notice and Date of Termination.

a) Notice of Termination. Except for termination as specified in Section 3(a), any termination of the Executive s employment

by the Company or any such termination by the Executive shall be communicated by written Notice of Termination to the other party hereto. For purposes of this Agreement, a Notice of Termination shall mean a notice which shall indicate

the specific termination provision in this Agreement relied upon.

b) Date of Termination. Date of Termination shall

mean: (i) if the Executive s employment is terminated by his death, the date of his death; (ii) if the Executive s employment is terminated on account of disability under Section 3(b) or by the Company for Cause under

Section 3(c), the date on which Notice of Termination is given; (iii) if the Executive s employment is terminated by the Company under Section 3(d), the date on which a Notice of Termination is given; (iv) if the

Executive s employment is terminated by the Executive under Section 3(e) without Good Reason, 30 days after the date on which a Notice of Termination is given, and (v) if the Executive s employment is terminated by the Executive

under Section 3(e) for Good Reason, the date on which a Notice of Termination is given after the end of the Cure Period. Notwithstanding the foregoing, in the event that the Executive gives a Notice of Termination to the Company, the Company

may unilaterally accelerate the Date of Termination and such acceleration shall not result in a termination by the Company for purposes of this Agreement.

5. Compensation Upon Termination by the Company without Cause or by the Executive for Good Reason Outside the Change in Control Period.

During the Term, if the Executive s employment is terminated by the Company without Cause as provided in Section 3(d), or the Executive terminates his employment for Good Reason as provided in Section 3(e), each outside of the Change

in Control Period (as defined below), then the Company shall pay the Executive his Accrued Benefit. In addition, subject to the Executive signing a separation agreement and release substantially in the form attached hereto as Exhibit A (the

Separation Agreement and Release ) and the Separation Agreement and Release becoming irrevocable, all within 60 days after the Date of Termination (or such shorter period as set forth in the Separation Agreement and Release):

a) the Company shall pay the Executive an amount equal to 0.75 times the Executive s

Base Salary (the Severance Amount ). Notwithstanding the foregoing, if the Executive breaches any of the provisions contained in Section 8 of this Agreement or the Restrictive Covenant Agreement, all payments of the Severance Amount

shall immediately cease; and

b) if the Executive was participating in the Company s group health plan immediately prior to the Date

of Termination and elects COBRA health continuation, then the Company shall pay the monthly employer COBRA premium for the same level of group health coverage as in effect for the Executive on the Date of Termination until the earliest of the

following: (i) the nine (9) month anniversary of the Date of Termination; (ii) the Executive s eligibility for group health coverage through other employment; or (iii) the end of the Executive s eligibility under COBRA

for continuation coverage for health care. Notwithstanding the foregoing, if the Company determines at any time that its payments pursuant to this paragraph may be taxable income to the Executive, it may convert such payments to payroll payments

directly to the Executive on the Company s regular payroll dates, which shall be subject to tax-related deductions and withholdings.

The amounts payable under this Section 5 shall be paid out in substantially equal installments in accordance with the Company s payroll practice

over nine (9) months commencing within 60 days after the Date of Termination; provided, however, that if the 60-day period begins in one calendar year and ends in a second calendar year, the Severance

Amount shall begin to be paid in the second calendar year by the last day of such 60-day period; provided, further, that the initial payment shall include a catch-up

payment to cover amounts retroactive to the day immediately following the Date of Termination. Each payment pursuant to this Agreement is intended to constitute a separate payment for purposes of Treasury Regulation Section l.409A-2(b)(2).

6. Compensation Upon Termination by the Company without Cause or by the

Executive for Good Reason within the Change in Control Period. The provisions of this Section 6 shall apply in lieu of, and expressly supersede, the provisions of Section 5 regarding severance pay and benefits upon a termination by the

Company without Cause or by the Executive for Good Reason if such termination of employment occurs within 12 months after the occurrence of the first event constituting a Change in Control (such period, the Change in Control Period ).