Exhibit 4.1




	
  

  	
  THIS CERTIFIES
  THAT is the owner of CUSIP DATED COUNTERSIGNED AND REGISTERED: COMPUTERSHARE
  TRUST COMPANY, N.A. TRANSFER AGENT AND REGISTRAR, FULLY-PAID AND
  NON-ASSESSABLE SHARES OF COMMON STOCK OF Blueprint Medicines Corporation
  (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. COMMON STOCK PAR VALUE $0.001
  COMMON STOCK THIS CERTIFICATE IS TRANSFERABLE IN CANTON, MA, JERSEY CITY, NJ
  AND COLLEGE STATION, TX SEE REVERSE FOR CERTAIN DEFINITIONS Certificate
  Number Shares . BLUEPRINT MEDICINES CORPORATION INCORPORATED UNDER THE LAWS
  OF THE STATE OF DELAWARE President, Chief Executive Officer Treasurer, Chief
  Business Officer By AUTHORIZED SIGNATURE 2011 DELAWARE BLUEPRINT MEDICINES
  CORPORATION ZQ|CERT#|COY|CLS|RGSTRY|ACCT#|TRANSTYPE|RUN#|TRANS# 09627Y 10 9
  DD-MMM-YYYY * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * *
  * * * * * * * * * * * * * * * * * 000000* * * * * * * * * * * * * * * * * * *
  * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * * * * * * * *
  * * * * ** 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. 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.
  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. 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
  **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
  00000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****00
  0000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000
  000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****000000**Shares****0000
  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
  **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****000000**S
  ***ZERO HUNDRED THOUSAND ZERO HUNDRED AND ZERO*** MR. SAMPLE & MRS.
  SAMPLE & MR. SAMPLE & MRS. SAMPLE ZQ00000000 Certificate Numbers
  1234567890/1234567890 1234567890/1234567890 1234567890/1234567890
  1234567890/1234567890 1234567890/1234567890 1234567890/1234567890 Total
  Transaction Num/No. 123456 Denom. 123456 Total 1234567 MR A SAMPLE
  DESIGNATION (IF ANY) ADD 1 ADD 2 ADD 3 ADD 4 PO BOX 43004, Providence, RI
  02940-3004 CUSIP XXXXXX XX X Holder ID XXXXXXXXXX Insurance Value
  1,000,000.00 Number of Shares 123456 DTC 12345678 123456789012345 

  






 


 












	
  

  	
  The IRS
  requires that we report the cost basis of certain shares acquired after
  January 1, 2011. If your shares were covered by the legislation and you have
  sold or transferred the shares and requested a specific cost basis
  calculation method, we have processed as requested. If you did not specify a
  cost basis calculation method, we have defaulted to the first in, first out
  (FIFO) method. Please visit our website or consult your tax advisor if you
  need additional information about cost basis. If you do not keep in contact
  with us or do not have any activity in your account for the time periods
  specified by state law, your property could become subject to state unclaimed
  property laws and transferred to the appropriate state. For value received,
  hereby sell, assign and transfer unto Shares Attorney 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.
  PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE (PLEASE
  PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE)
  of the common stock represented by the within Certificate, and do hereby
  irrevocably constitute and appoint to transfer the said stock on the books of
  the within-named Company with full power of substitution in the premises. .
  BLUEPRINT MEDICINES CORPORATION 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. 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 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 UNIF
  TRF MIN ACT - Custodian (until age ) and not as tenants in common (Cust)
  under Uniform Transfers to Minors Act (Minor) (State) Additional
  abbreviations may also be used though not in the above list.