EX-4.1



 Exhibit 4.1 
  






 
 CUSIP/IDENTIFIER XXXXXX XX X Holder ID XXXXXXXXXX Insurance Value 00.1,000,000 Number of Shares 123456 DTC
12345678901234512345678 PO BOX 43004, Providence, RI 02940-3004 Certificate Numbers Num/No Denom. Total. MR A SAMPLE 1234567890/1234567890 111 DESIGNATION (IF ANY) 1234567890/1234567890 222 ADD 1 ADD 2 1234567890/1234567890 333 1234567890/1234567890
444 ADD 3 ADD 4 1234567890/1234567890 555 1234567890/1234567890 666 Total Transaction 7 . ZQ|CERT# |COY|CLS|RGSTRY|ACCT#|TRANSTYPE|RUN#|TRANS# COMMON STOCK COMMON STOCK PAR VALUE $0.001 Certificate Shares Number * * 000000 **** **** **** **** ** * *
* 000000 **** **** **** **** * ZQ00000000 **** 000000 **** **** **** **** MAGENTA THERAPEUTICS, INC. **** * 000000 **** **** **** *** **** ** 000000 **** **** **** ** INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE ** Mr. Alexander David Sample
**** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample SEE REVERSE FOR CERTAIN DEFINITIONS **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander
David Sample **** Mr. Alexander David Sample **** Mr. Alexander David THIS CERTIFIES THAT Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David
Sample **** Mr. MR. Alexander David SAMPLE Sample **** Mr. Alexander David &Sample MRS. **** Mr. Alexander SAMPLE David Sample **** Mr. Alexander & David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr.
Alexander David Sample **** Mr Alexander David Sample **** Mr. Alexander David Sample **** CUSIP 55910K 10 8 Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr.
Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander MR. David Sample SAMPLE **** Mr. Alexander
David Sample **** &Mr. Alexander MRS. David Sample SAMPLE **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David
Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander David Sample **** Mr. Alexander
David Sample **** Mr. Alexander David Sample **** Mr. Sample **** Mr. Sample is the owner of **000000**Shares **** 000000 ** Shares **** 000000** Shares **** 000000**Shares **** 000000 **Shares **** 000000**Shares **** 000000 ** Shares **** 000000
**Shares*** *000000**Shares **** 000000**Shares **** 000000**Shares **** 000000 ** Shares **** 000000**Shares **** 000000 **Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000** Shares ****
000000**Shares **** 000000**Shares **** 000000**Shares **** 000000 **Shares **** 000000** Shares **** 0 THIS CERTIFICATE IS TRANSFERABLE IN 00000**Shares **** 000000**Shares **** 000000** Shares **** 000000**Shares **** 000000**Shares **** 000000 **
Shares **** 000000**Shares **** 000000**Shares **** 00 ***ZERO HUNDRED THOUSAND 0000**Shares **** 000000 **Shares **** 000000**Shares **** 000000** Shares **** 000000**Shares **** 000000**Shares **** 000000 **Shares **** 000000**Shares **** 000
CITIES DESIGNATED BY THE TRANSFER 000**Shares **** 000000 **Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 0000 AGENT, AVAILABLE ONLINE AT 00**Shares ****
000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 00000 0**Shares **** 000000**Shares **** 000000**Shares **** 000000** Shares **** 000000 **Shares ****
000000**Shares **** 000000** Shares **** 000000**Shares **** 000000 ZERO HUNDRED AND ZERO*** www.computershare.com **Shares **** 000000** Shares **** 000000**Shares **** 0000 00**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares
**** 000000 ** Shares **** 000000* *Shares **** 000000 **Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000 **Shares **** 000000**Shares **** 000000**Shares **** 000000** Shares **** 000000**Shares **** 000000** Shares
**** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**Shares **** 000000**S FULLY-PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK OF Magenta Therapeutics, Inc. (hereinafter called the “Company”),
transferable on the books of the Company in person or by duly authorized attorney, upon surrender of this Certificate properly endorsed. This Certificate and the shares represented hereby, are issued and shall be held subject to all of the
provisions of the Certificate of Incorporation, as amended, and the By-Laws, as amended, of the Company (copies of which are on file with the Company and with the Transfer Agent), to all of which each holder, by acceptance hereof, assents. This
Certificate is not valid unless countersigned and registered by the Transfer Agent and Registrar. Witness the facsimile seal of the Company and the facsimile signatures of its duly authorized officers. DATED DD-MMM-YYYY ERAP H E COUNTERSIGNED AND
REGISTERED: FACSIMILE SIGNATURE TO COME T O UT T A ORP RAT I COMPUTERSHARE TRUST COMPANY, N.A. N NC ED C President E I S, TRANSFER AGENT AND REGISTRAR, G I N A M . C June 17, 2015 DEL RE FACSIMILE SIGNATURE TO COME AWA By Secretary AUTHORIZED
SIGNATURE 







   

 
 MAGENTA THERAPEUTICS, INC. 

THE COMPANY WILL FURNISH WITHOUT CHARGE TO EACH SHAREHOLDER WHO SO REQUESTS, A SUMMARY OF THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING,
OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OF THE COMPANY AND THE QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH PREFERENCES AND RIGHTS, AND THE VARIATIONS IN RIGHTS, PREFERENCES AND LIMITATIONS DETERMINED FOR EACH SERIES, WHICH
ARE FIXED BY THE CERTIFICATE OF INCORPORATION OF THE COMPANY, AS AMENDED, AND THE RESOLUTIONS OF THE BOARD OF DIRECTORS OF THE COMPANY, AND THE AUTHORITY OF THE BOARD OF DIRECTORS TO DETERMINE VARIATIONS FOR FUTURE SERIES. SUCH REQUEST MAY BE MADE
TO THE OFFICE OF THE SECRETARY OF THE COMPANY OR TO THE TRANSFER AGENT. THE BOARD OF DIRECTORS MAY REQUIRE THE OWNER OF A LOST OR DESTROYED STOCK CERTIFICATE, OR HIS LEGAL REPRESENTATIVES, TO GIVE THE COMPANY A BOND TO INDEMNIFY IT AND ITS TRANSFER
AGENTS AND REGISTRARS AGAINST ANY CLAIM THAT MAY BE MADE AGAINST THEM ON ACCOUNT OF THE ALLEGED LOSS OR DESTRUCTION OF ANY SUCH CERTIFICATE. 
  

					
	  

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written
out in full according to applicable laws or regulations:

	 	 
	 TEN COM - as tenants in
common
	 	UNIF GIFT MIN ACT -
                                        
Custodian                                    
	 	 	                        
                    (Cust)                    
                             (Minor)
	
TEN ENT - as tenants by the entireties  
	 	under Uniform Gifts to Minors
Act                                        
                            
	 	 	    
                                  (State)
	 JT TEN   - as
joint tenants with right of survivorship and not as tenants in common
	 	 UNIF TRF MIN ACT -
                                        
Custodian (until age                    )

                    (Cust)   
                                     

	 	 	                        
                under Uniform Transfers to Minors
Act                    
	 	 	            (Minor)           
                                         
                                 (State)
	
Additional abbreviations may also be used though not in the above list.

 


 PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE 

					
	For value received,
                                    	  	hereby sell, assign and transfer unto  	  	 

  
  

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE) 
  

 
  

 
  

 
 Shares of the common stock represented by the within
Certificate, and do hereby irrevocably constitute and appoint 
  
  

Attorney to transfer the said stock on the books of the within-named Company with full power of substitution in the premises. 

 

			
	 Dated:
                                         
                   20
                        
  

Signature:
                                         
                                         
 
  
 Signature:
                                         
                                         
 
  
 Notice: The signature to
this assignment must correspond with the name as written upon the face of the certificate, in every particular, without alteration or enlargement, or any change whatever.
	  	
Signature(s) Guaranteed: Medallion Guarantee Stamp

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (Banks, Stockbrokers, Savings and Loan Associations and Credit Unions)
WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15.

		
		  	 The IRS requires that the named transfer agent (“we”) report the cost basis of certain shares or units acquired after
January 1, 2011. If your shares or units are covered by the legislation, and you requested to sell or transfer the shares or units using a specific cost basis calculation method, then we have processed as you requested. If you did not specify a
cost basis calculation method, then we have defaulted to the first in, first out (FIFO) method. Please consult your tax advisor if you need additional information about cost basis.

 
 If you do not keep in contact with the issuer or do not have any activity in your
account for the time period specified by state law, your property may become subject to state unclaimed property laws and transferred to the appropriate state.