EX-10.2



 Exhibit 10.2 
 BLUEBIRD BIO, INC. 
 FOURTH AMENDMENT TO THE 

2010 STOCK OPTION AND GRANT PLAN 
 The bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”) is hereby amended by the Board of Directors and stockholders of bluebird bio, Inc., a Delaware corporation, as
follows: 
 Section 3(a) of the Plan is hereby amended by deleting the first sentence of Section 3(a) and substituting
therefor the following: 
 “The maximum number of shares of Stock reserved and available for issuance under the Plan shall
be the sum of (i) 81,953,382 shares and (ii) such number of shares as equals that number of stock options or awards returned to the Company’s 2002 Employee, Director and Consultant Stock Plan, as amended and in effect from time to
time, after January 16, 2013 as a result of the expiration, cancellation or termination of such stock options or awards, subject to adjustment as provided in Section 3(b).” 
 ADOPTED BY BOARD OF DIRECTORS: January 16, 2013 
 ADOPTED BY STOCKHOLDERS: January 16,
2013 







 BLUEBIRD BIO, INC. 

THIRD AMENDMENT TO THE 
 2010 STOCK OPTION AND GRANT PLAN 
 The bluebird bio, Inc. 2010 Stock Option
and Grant Plan (the “Plan”) is hereby amended by the Board of Directors and stockholders of bluebird bio, Inc., a Delaware corporation, as follows: 
 Section 3(a) of the Plan is hereby amended by deleting the first sentence of Section 3(a) and substituting therefor the following: 

“The maximum number of shares of Stock reserved and available for issuance under the Plan shall be the sum of (i) 65,322,771
shares and (ii) such number of shares as equals that number of stock options or awards returned to the Company’s 2002 Employee, Director and Consultant Stock Plan, as amended and in effect from time to time, after July 23, 2012 as a
result of the expiration, cancellation or termination of such stock options or awards, subject to adjustment as provided in Section 3(b).” 
 ADOPTED BY BOARD OF DIRECTORS: July 23, 2012 
 ADOPTED BY STOCKHOLDERS: July 23, 2012








 BLUEBIRD BIO, INC. 

SECOND AMENDMENT TO THE 
 2010 STOCK OPTION AND GRANT PLAN 
 The bluebird bio, Inc. 2010 Stock Option
and Grant Plan, as amended (the “Plan”), is hereby amended by the Board of Directors and stockholders of bluebird bio, Inc., a Delaware corporation, as follows: 

Section 3(a) of the Plan is hereby amended by deleting the first sentence of Section 3(a) and substituting therefor the following:

 “The maximum number of shares of Stock reserved and available for issuance under the Plan shall be the sum of
(i) 46,136,871 shares and (ii) such number of shares as equals that number of stock options or awards returned to the Company’s 2002 Employee, Director and Consultant Stock Plan, as amended and in effect from time to time, after the
Effective Date (September 10, 2010) as a result of the expiration, cancellation or termination of such stock options or awards, subject to adjustment as provided in Section 3(b).” 
 ADOPTED BY BOARD OF DIRECTORS: April 24, 2012 
 ADOPTED BY STOCKHOLDERS: May 7, 2012








 BLUEBIRD BIO, INC. 

FIRST AMENDMENT TO THE 
 2010 STOCK OPTION AND GRANT PLAN 
 The bluebird bio, Inc. 2010 Stock Option
and Grant Plan (the “Plan”) is hereby amended by the Board of Directors and stockholders of bluebird bio, Inc., a Delaware corporation, as follows: 
 Section 3(a) of the Plan is hereby amended by deleting the first sentence of Section 3(a) and substituting therefor the following: 

“The maximum number of shares of Stock reserved and available for issuance under the Plan shall be the sum of (i) 41,636,871
shares and (ii) such number of shares as equals that number of stock options or awards returned to the Company’s 2002 Employee, Director and Consultant Stock Plan, as amended and in effect from time to time, after the Effective Date as a
result of the expiration, cancellation or termination of such stock options or awards, subject to adjustment as provided in Section 3(b).” 
 ADOPTED BY BOARD OF DIRECTORS: April 15, 2011 
 ADOPTED BY STOCKHOLDERS: April 15, 2011

  







 BLUEBIRD BIO, INC. 

2010 STOCK OPTION AND GRANT PLAN 
 SECTION 1. GENERAL PURPOSE OF THE PLAN; DEFINITIONS 
 The name of the plan
is the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”). The purpose of the Plan is to encourage and enable the officers, employees, directors, Consultants and other key persons (including prospective employees, but
conditioned on their employment) of bluebird bio, Inc. (f/k/a Genetix Pharmaceuticals, Inc.), a Delaware corporation (including any successor entity, the “Company”) and any Subsidiary, upon whose judgment, initiative and efforts the
Company largely depends for the successful conduct of its business, to acquire a proprietary interest in the Company. 
 The
following terms shall be defined as set forth below: 
 “Affiliate” of any Person means a Person that directly
or indirectly, through one or more intermediaries, controls, is controlled by or is under common control with the first mentioned Person. A Person shall be deemed to control another Person if such first Person possesses directly or indirectly the
power to direct, or cause the direction of, the management and policies of the second Person, whether through the ownership of voting securities, by contract or otherwise. 
 “Award” or “Awards,” except where referring to a particular category of grant under the Plan, shall include Incentive Stock Options, Non-Qualified Stock Options,
Restricted Stock Awards, Unrestricted Stock Awards, Restricted Stock Units or any combination of the foregoing. 

“Award Agreement” means a written or electronic agreement setting forth the terms and provisions applicable to an Award
granted under the Plan. Each Award Agreement may contain terms and conditions in addition to those set forth in the Plan; provided, however, that except to the extent explicitly provided to the contrary, in the event of any conflict in the
terms of the Plan and the Award Agreement, the terms of the Plan shall govern. 
 “Bankruptcy” shall mean
(i) the filing of a voluntary petition under any bankruptcy or insolvency law, or a petition for the appointment of a receiver or the making of an assignment for the benefit of creditors, with respect to the Holder, (ii) the Holder being
subjected involuntarily to such a petition or assignment or to an attachment or other legal or equitable interest with respect to the Holder’ s assets, which involuntary petition or assignment or attachment is not discharged within 60 days
after its date, or (iii) the Holder being subject to a transfer of its Issued Shares or Award(s) by operation of law (including by divorce, even if not insolvent), except by reason of death. 

“Board” means the Board of Directors of the Company. 

“Cause” shall have the meaning as set forth in the Award Agreement(s). In the case that any Award Agreement does not
contain a definition of “Cause,” it shall mean (i) the grantee’s dishonest statements or acts with respect to the Company or any Affiliate of the Company, or 

  
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any of the Company’s current or prospective customers, suppliers vendors or other third parties with which such entity does business; (ii) the grantee’s commission of (A) a
felony or (B) any misdemeanor involving moral turpitude, deceit, dishonesty or fraud; (iii) the grantee’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, after written notice given to the grantee by the Company; (iv) the grantee’s gross negligence, willful misconduct or insubordination with respect to the Company or any Affiliate of the
Company; or (v) the grantee’s violation of any provision of any agreement(s) between the grantee and the Company relating to noncompetition, nondisclosure and/or assignment of inventions. 

“Chief Executive Officer” means the Chief Executive Officer of the Company or, if there is no Chief Executive Officer,
then the President of the Company. 
 “Code” means the Internal Revenue Code of 1986, as amended, and any
successor Code, and related rules, regulations and interpretations. 
 “Committee” means the Committee of the
Board referred to in Section 2. 
 “Consultant” means any natural person that provides bona fide services
to the Company (including a Subsidiary), and such services are not in connection with the offer or sale of securities in a capital-raising transaction and do not directly or indirectly promote or maintain a market for the Company’s securities.

 “Effective Date” means the date on which the Plan is adopted as set forth on the final page of the Plan.

 “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations
thereunder. 
 “Fair Market Value” of the Stock on any given date means the fair market value of the Stock
determined in good faith by the Committee based on the reasonable application of a reasonable valuation method not inconsistent with Section 409A of the Code. If the Stock is admitted to trade on a national securities exchange, the
determination shall be made by reference to the closing price. If the date for which Fair Market Value is determined is the first day when trading prices for the Stock are reported on a national securities exchange, the Fair Market Value shall be
the “Price to the Public” (or equivalent) set forth on the cover page for the final prospectus relating to the Company’s Initial Public Offering. 
 “Grant Date” means the date that the Committee designates in its approval of an Award in accordance with applicable law as the date on which the Award is granted, which date may not
precede the date of such Committee approval. 
 “Holder” means, with respect to an Award or any Issued Shares,
the Person holding such Award or Issued Shares, including the initial recipient of the Award or any Permitted Transferee. 

“Incentive Stock Option” means any Stock Option designated and qualified as an “incentive stock option” as
defined in Section 422 of the Code. 

  
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 “Incumbent Directors” shall mean directors who either (A) are
directors of the Company as of the date this Plan is first adopted by the Board, or (B) are elected, or nominated for election, to the Board with the affirmative votes of at least a majority of the Incumbent Directors at the time of such
election or nomination (but shall not include an individual whose election or nomination is in connection with an actual or threatened proxy contest relating to the election of directors to the Company). 

“Initial Public Offering” means the consummation of the first firm commitment underwritten public offering pursuant to
an effective registration statement under the Securities Act covering the offer and sale by the Company of its equity securities, as a result of or following which the Stock shall be publicly held. 

“Issued Shares” means, collectively, all outstanding Shares issued pursuant to Restricted Stock Awards, Unrestricted
Stock Awards and Restricted Stock Units and all Option Shares. 
 “NASDAQ” means the NASDAQ Stock Market LLC.

 “Non-Qualified Stock Option” means any Stock Option that is not an Incentive Stock Option. 

“Option” or “Stock Option” means any option to purchase shares of Stock granted pursuant to
Section 5. 
 “Option Shares” means outstanding shares of Stock that were issued to a Holder upon the
exercise of a Stock Option. 
 “Permitted Transferees” shall mean any of the following to whom a Holder may
transfer Issued Shares hereunder (as set forth in Section 9(a)(ii)(A)): the Holder’s child, stepchild, grandchild, parent, stepparent, grandparent, spouse, former spouse, sibling, niece, nephew, mother-in-law, father-in-law, son-in-law,
daughter-in-law, brother-in-law, or sister-in-law, including adoptive relationships, any person sharing the Holder’s household (other than a tenant or employee), a trust in which these persons have more than fifty percent of the beneficial
interest, a foundation in which these persons control the management of assets, and any other entity in which these persons own more than fifty percent of the voting interests; provided, however, that any such trust does not require or permit
distribution of any Issued Shares during the term of the Award Agreement unless subject to its terms. Upon the death of the Holder, the term Permitted Transferees shall also include such deceased Holder’s estate, executors, administrators,
personal representatives, heirs, legatees and distributees, as the case may be. 
 “Person” shall mean any
individual, corporation, partnership (limited or general), limited liability company, limited liability partnership, association, trust, joint venture, unincorporated organization or any similar entity. 

“Repurchase Event” means (i) a Sale Event or (ii) the Holder’s Bankruptcy. 

“Restricted Stock Award” means Awards granted pursuant to Section 6 and “Restricted Stock” means
Shares granted pursuant to such Awards. 

  
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 “Restricted Stock Unit” means an Award of phantom stock units to a grantee,
which may be settled in cash or stock as determined by the Committee, pursuant to Section 8. 
 “Sale
Event” means the consummation of (i) the dissolution or liquidation of the Company, (ii) the sale of all or substantially all of the assets of the Company on a consolidated basis to an unrelated person or entity, (iii) a
merger, reorganization or consolidation involving the Company in which the shares of voting stock of the Company outstanding immediately prior to such transaction represent or are converted into or exchanged for securities of the surviving or
resulting entity immediately upon completion of such transaction which represent less than 50 percent of the outstanding voting power of such surviving or resulting entity, (iv) the acquisition of all or a majority of the outstanding voting
stock of the Company in a single transaction or a series of related transactions by a Person or group of Persons, (v) a change in the composition of the Board, as a result of which fewer than a majority of the directors are Incumbent Directors,
or (vi) any other acquisition of the business of the Company, as determined by the Board; provided, however, that the Company’s Initial Public Offering, any subsequent public offering or another capital raising event, or a merger
effected solely to change the Company’s domicile shall not constitute a “Sale Event.” 
 “Section
409A” means Section 409A of the Code and the regulations and other guidance promulgated thereunder. 

“Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations thereunder. 

“Service Relationship” means any relationship as a full-time employee, part-time employee, director or other key person
(including Consultants) of the Company or any Subsidiary or any successor entity; provided that a change in status (e.g., from full-time employee to part-time employee or from full-time employee to Consultant or otherwise) shall, unless otherwise
provided in the Award Agreement, constitute a termination of the Award recipient’s Service Relationship with the Company and its Subsidiaries. 
 “Shares” means shares of Stock. 
 “Stock” means
the Common Stock, par value $0.01 per share, of the Company. 
 “Subsidiary” means any corporation or other
entity (other than the Company) in which the Company has more than a 50 percent interest, either directly or indirectly. 

“Ten Percent Owner” means an employee who owns or is deemed to own (by reason of the attribution rules of
Section 424(d) of the Code) more than 10 percent of the combined voting power of all classes of stock of the Company or any parent of the Company or any Subsidiary. 
 “Termination Event” means the termination of the Award recipient’s Service Relationship with the Company and its Subsidiaries for any reason whatsoever, regardless of the
circumstances thereof, and including, without limitation, upon death, disability, retirement, discharge or resignation for any reason, whether voluntarily or involuntarily. The following shall not constitute a Termination Event: (i) a transfer
to the service of the Company from a Subsidiary or from the Company to a Subsidiary, or from one Subsidiary to another Subsidiary 

  
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or (ii) an approved leave of absence for military service or sickness, or for any other purpose approved by the Committee, if the individual’s right to re-employment is guaranteed
either by a statute or by contract or under the policy pursuant to which the leave of absence was granted or if the Committee otherwise so provides in writing. 
 “Unrestricted Stock Award” means any Award granted pursuant to Section 7 and “Unrestricted Stock” means Shares granted pursuant to such Awards. 

 

	SECTION 2.	ADMINISTRATION OF PLAN; COMMITTEE AUTHORITY TO SELECT GRANTEES AND DETERMINE AWARDS 


(a) Administration of Plan. The Plan shall be administered by the Board, or at the discretion of the Board, by a committee of the
Board, comprised of not less than two Directors. All references herein to the “Committee” shall be deemed to refer to the group then responsible for administration of the Plan at the relevant time (i.e., either the Board of Directors or a
committee or committees of the Board, as applicable). 
 (b) Powers of Committee. The Committee shall have the power and
authority to grant Awards consistent with the terms of the Plan, including the power and authority: 
 (i) to select the
individuals to whom Awards may from time to time be granted; 
 (ii) to determine the time or times of grant, and the amount, if
any, of Incentive Stock Options, Non-Qualified Stock Options, Restricted Stock Awards, Unrestricted Stock Awards, Restricted Stock Units, or any combination of the foregoing, granted to any one or more grantees; 

(iii) to determine the number of shares of Stock to be covered by any Award and, subject to the provisions of Section 5(a)(i) below,
the price, exercise price, conversion ratio or other price relating thereto; 
 (iv) to determine and, subject to
Section 12, to modify from time to time the terms and conditions, including restrictions, not inconsistent with the terms of the Plan, of any Award, which terms and conditions may differ among individual Awards and grantees, and to approve the
form of Award Agreements; 
 (v) to accelerate at any time the exercisability or vesting of all or any portion of any Award;

 (vi) to impose any limitations on Awards granted under the Plan, including limitations on transfers, repurchase provisions
and the like, and to exercise repurchase rights or obligations; 
 (vii) subject to any restrictions imposed by
Section 409A, to extend at any time the period in which Stock Options may be exercised; and 

  
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 (viii) at any time to adopt, alter and repeal such rules, guidelines and practices for
administration of the Plan and for its own acts and proceedings as it shall deem advisable; to interpret the terms and provisions of the Plan and any Award (including related written instruments); to make all determinations it deems advisable for
the administration of the Plan; to decide all disputes arising in connection with the Plan; and to otherwise supervise the administration of the Plan. 
 All decisions and interpretations of the Committee shall be binding on all persons, including the Company and Plan grantees. 
 (c) Award Agreement. Awards under the Plan shall be evidenced by Award Agreements that set forth the terms, conditions and limitations for each Award. 

(d) Indemnification. Neither the Board nor the Committee, nor any member of either or any delegate thereof, shall be liable for
any act, omission, interpretation, construction or determination made in good faith in connection with the Plan, and the members of the Board and the Committee (and any delegate thereof) shall be entitled in all cases to indemnification and
reimbursement by the Company in respect of any claim, loss, damage or expense (including, without limitation, reasonable attorneys’ fees) arising or resulting therefrom to the fullest extent permitted by law and/or under the Company’s
governing documents, including its certificate of incorporation or bylaws, or any directors’ and officers’ liability insurance coverage which may be in effect from time to time and/or any indemnification agreement between such individual
and the Company. 
 (e) Foreign Award Recipients. Notwithstanding any provision of the Plan to the contrary, in order to
comply with the laws in other countries in which the Company and any Subsidiary operate or have employees or other individuals eligible for Awards, the Committee, in its sole discretion, shall have the power and authority to: (i) determine
which Subsidiaries, if any, shall be covered by the Plan; (ii) determine which individuals, if any, outside the United States are eligible to participate in the Plan; (iii) modify the terms and conditions of any Award granted to
individuals outside the United States to comply with applicable foreign laws; (iv) establish subplans and modify exercise procedures and other terms and procedures, to the extent the Committee determines such actions to be necessary or
advisable (and such subplans and/or modifications shall be attached to the Plan as appendices); provided, however, that no such subplans and/or modifications shall increase the share limitation contained in Section 3(a) hereof;
and (v) take any action, before or after an Award is made, that the Committee determines to be necessary or advisable to obtain approval or comply with any local governmental regulatory exemptions or approvals. 

 

	SECTION 3.	STOCK ISSUABLE UNDER THE PLAN; MERGERS AND OTHER TRANSACTIONS; SUBSTITUTION 


(a) Stock Issuable. The maximum number of shares of Stock reserved and available for issuance under the Plan shall be the sum of
(i) 26,436,861 shares and (ii) such number of shares as equals that number of stock options or awards returned to the Company’s 2002 Employee, Director and Consultant Stock Plan, as amended and in effect from time to time, after the
Effective Date as a result of the expiration, cancellation or termination of such stock options 

  
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or awards, subject to adjustment as provided in Section 3(b). For purposes of this limitation, the shares of Stock underlying any Awards that are forfeited, canceled, withheld upon exercise
of an Option or settlement of an Award to cover the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of Stock or otherwise terminated (other than by exercise), in each case shall be added
back to the shares of Stock available for issuance under the Plan. Subject to such overall limitations, shares of Stock may be issued up to such maximum number pursuant to any type or types of Award. The shares available for issuance under the Plan
may be authorized but unissued shares of Stock or shares of Stock reacquired by the Company. 
 (b) Changes in Stock.
Subject to Section 3(c) hereof, if, as a result of any reorganization, recapitalization, reclassification, stock dividend, stock split, reverse stock split or other similar change in the Company’s capital stock, the outstanding shares of
Stock are increased or decreased or are exchanged for a different number or kind of shares or other securities of the Company, or additional shares or new or different shares or other securities of the Company or other non-cash assets are
distributed with respect to such shares of Stock or other securities, or, if, as a result of any merger or consolidation, or sale of all or substantially all of the assets of the Company, the outstanding shares of Stock are converted into or
exchanged for securities of the Company or any successor entity (or a parent or subsidiary thereof), the Committee shall make an appropriate and equitable or proportionate adjustment in (i) the maximum number of shares reserved for issuance
under the Plan, (ii) the number and kind of shares or other securities subject to any then outstanding Awards under the Plan, (iii) the repurchase price, if any, per share subject to each outstanding Award, and (iv) the exercise price
for each share subject to any then outstanding Stock Options under the Plan, without changing the aggregate exercise price (i.e., the exercise price multiplied by the number of Stock Options) as to which such Stock Options remain exercisable. The
adjustment by the Committee shall be final, binding and conclusive. No fractional shares of Stock shall be issued under the Plan resulting from any such adjustment, but the Committee in its discretion may make a cash payment in lieu of fractional
shares. 
 (c) Sale Events. 
 (i) Options. 
 (A) In the case of and subject to the
consummation of a Sale Event, the Plan and all Options issued hereunder shall terminate upon the effective time of any such Sale Event unless provision is made in connection with the Sale Event for the assumption or continuation of Options
theretofore granted by the successor entity, or the substitution of such Options with new Options of the successor entity or parent thereof, with an equitable or proportionate adjustment as to the number and kind of shares and, if appropriate, the
per share exercise prices, as such parties shall agree (after taking into account any acceleration hereunder and/or pursuant to the terms of any Award Agreement). 

  
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 (B) In the event of the termination of the Plan and all Options issued
hereunder pursuant to Section 3(c), each Holder of Options shall be permitted, within a specified period of time prior to the consummation of the Sale Event as determined by the Committee, to exercise all such Options which are then exercisable
or will become exercisable as of the effective time of the Sale Event; provided, however, that the exercise of Options not exercisable prior to the Sale Event shall be subject to the consummation of the Sale Event. 

(C) Notwithstanding anything to the contrary in Section 3(c)(i)(A), in the event of a Sale Event, the Company shall
have the right, but not the obligation, to make or provide for a cash payment to the grantees holding Options in exchange for the cancellation thereof, in an amount equal to the difference between (A) the value as determined by the Committee of
the consideration payable per share of Stock pursuant to the Sale Event (the “Sale Price”) times the number of shares of Stock subject to outstanding Options (to the extent then vested and exercisable, including by reason of acceleration
in connection with such Sale Event, at prices not in excess of the Sale Price) and (B) the aggregate exercise price of all such outstanding vested Options. 
 (ii) Option Shares. Unless otherwise provided in an Award Agreement, in the case of and subject to the consummation of a Sale Event, Option Shares shall be subject to the repurchase right set forth
in Section 9(c)(i). 
 (iii) Restricted Stock and Restricted Stock Unit Awards. 

(A) In the case of and subject to the consummation of a Sale Event, all Restricted Stock and Restricted Stock Unit Awards
issued hereunder shall be forfeited immediately prior to the effective time of any such Sale Event unless provision is made in connection with the Sale Event for the assumption or continuation of such Awards by the successor entity, or the
substitution of such Awards with new Awards of the successor entity or parent thereof, with an equitable or proportionate adjustment as to the number and kind of shares subject to such Awards as such parties shall agree (after taking into account
any acceleration hereunder and/or pursuant to the terms of any Award Agreement). 
 (B) In the event of the
forfeiture of shares of Restricted Stock issued hereunder pursuant to Section 3(c)(iii)(A), such shares of Restricted Stock shall be repurchased from the Holder thereof at a price per share equal to the lower of the original per share purchase
price paid by the recipient (subject to adjustment as provided in Section 3(b)) or the current Fair Market Value of such shares, determined immediately prior to the effective time of the Sale Event. 

(C) Notwithstanding anything to the contrary in Section 3(c)(iii)(A), in the event of a Sale Event, the Company shall
have the right, but not the obligation, to make or provide for a cash payment to the grantees holding Restricted Stock or Restricted Stock Unit Awards in exchange for the cancellation thereof, in an amount equal to the Sale Price times the number of
shares of Stock subject to such Awards, to be paid at the time of such Sale Event or upon the later vesting of such Awards. 

  
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 (iv) Unrestricted Stock Awards. Unless otherwise provided in an Award Agreement, any
shares of Unrestricted Stock shall be treated in a Sale Event the same as all other Shares then outstanding. 
 SECTION 4. ELIGIBILITY

 Grantees under the Plan will be such full or part-time officers and other employees, directors, Consultants and key persons
(including prospective employees, but conditioned on their employment) of the Company and any Subsidiary who are selected from time to time by the Committee in its sole discretion; provided, however, that an Incentive Stock Option may
be granted only to a person who, at the time the Incentive Stock Option is granted, is an employee of the Company or any Subsidiary. 

SECTION 5. STOCK OPTIONS 
 Upon the grant of a Stock Option, the Company and the grantee shall enter into a Stock Option Award Agreement. The terms and conditions of each such Stock Option Award Agreement shall be determined by the
Committee, and such terms and conditions may differ among individual Awards and grantees. 
 Stock Options granted under the
Plan may be either Incentive Stock Options or Non-Qualified Stock Options. Incentive Stock Options may be granted only to employees of the Company or any Subsidiary that is a “subsidiary corporation” within the meaning of
Section 424(f) of the Code. To the extent that any Option does not qualify as an Incentive Stock Option, it shall be deemed a Non-Qualified Stock Option. 
 (a) Terms of Stock Options. The Committee in its discretion may grant Stock Options to eligible officers, employees, directors, Consultants and key persons of the Company or any Subsidiary. Stock
Options granted pursuant to this Section 5(a) shall be subject to the following terms and conditions and shall contain such additional terms and conditions, not inconsistent with the terms of the Plan, as the Committee shall deem desirable.

 (i) Exercise Price. The exercise price per share for the Stock covered by a Stock Option granted pursuant to
Section 5(a) shall be determined by the Committee at the time of grant but shall not be less than 100 percent of the Fair Market Value on the Grant Date. In the case of an Incentive Stock Option that is granted to a Ten Percent Owner, the
option price of such Incentive Stock Option shall not be less than 110 percent of the Fair Market Value on the Grant Date. 

(ii) Option Term. The term of each Stock Option shall be fixed by the Committee, but no Stock Option shall be exercisable more
than ten years after the date the Stock Option is granted. In the case of an Incentive Stock Option that is granted to a Ten Percent Owner, the term of such Stock Option shall be no more than five years from the Grant Date. 

(iii) Exercisability; Rights of a Stockholder. Stock Options shall become exercisable and/or vested at such time or times, whether
or not in installments, as shall be determined by the Committee at or after the Grant Date. The Award Agreement may permit an optionee to exercise all or a portion of a Stock Option immediately at grant; provided that the


  
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Option Shares issued upon such exercise shall be subject to restrictions and a vesting schedule identical to the vesting schedule of the related Stock Option and the optionee shall be required to
enter into a Restricted Stock Award Agreement and any other similar documentation required by the Company as a condition to exercise of such Stock Option. An optionee shall have the rights of a stockholder only as to shares acquired upon the
exercise of a Stock Option and not as to unexercised Stock Options. An optionee shall not be deemed to have acquired any such shares unless and until a Stock Option shall have been exercised pursuant to the terms hereof and the optionee’s name
shall have been entered on the books of the Company as a stockholder. 
 (iv) Method of Exercise. Stock Options may be
exercised by an optionee in whole or in part, by the optionee giving written notice of exercise to the Company, specifying the number of shares to be purchased. Payment of the purchase price may be made by one or more of the following methods (or
any combination thereof) to the extent provided in the Option Award Agreement: 
 (A) In cash, by certified or
bank check, by wire transfer of immediately available funds, or other instrument acceptable to the Committee; 

(B) If permitted by the Committee, by the optionee delivering to the Company a promissory note, if the Board has expressly
authorized the loan of funds to the optionee for the purpose of enabling or assisting the optionee to effect the exercise of his or her Stock Option; provided, that at least so much of the exercise price as represents the par value of the
Stock shall be paid other than with a promissory note if required by state law; 
 (C) If permitted by the
Committee and the Initial Public Offering has occurred (or the Stock otherwise becomes publicly-traded), through the delivery (or attestation to the ownership) of shares of Stock that have been purchased by the optionee on the open market or that
are beneficially owned by the optionee and are not then subject to restrictions under any Company plan. To the extent required to avoid variable accounting treatment under FAS 123R or other applicable accounting rules, such surrendered shares if
originally purchased from the Company shall have been owned by the optionee for at least six months. Such surrendered shares shall be valued at Fair Market Value on the exercise date; 

(D) If permitted by the Committee and the Initial Public Offering has occurred (or the Stock otherwise becomes
publicly-traded), by the optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to promptly deliver to the Company cash or a check payable and acceptable to the Company for the
purchase price; provided that in the event the optionee chooses to pay the purchase price as so provided, the optionee and the broker shall comply with such procedures and enter into such agreements of indemnity and other agreements as the
Committee shall prescribe as a condition of such payment procedure; and 
 (E) If permitted by the Committee,
with respect to Stock Options that are not Incentive Stock Options, by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Stock issuable upon exercise by the largest whole number of shares with a
Fair Market Value that does not exceed the aggregate exercise price. 

  
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 Payment instruments will be received subject to collection. No certificates for shares of
Stock so purchased will be issued to the optionee or, with respect to uncertificated Stock, no transfer to the optionee on the records of the Company will take place, until the Company has completed all steps required by law to be taken in
connection with the issuance and sale of the shares, which steps may include, without limitation, (i) receipt of a representation from the optionee at the time of exercise of the Option that the optionee is purchasing the shares for the
optionee’s own account and not with a view to any sale or distribution thereof, (ii) the legending of any certificate (or notation on any book entry) representing the shares to evidence the foregoing restrictions, (iii) obtaining from
optionee payment or provision for all withholding taxes due as a result of the exercise of the Option, and (iv) if required by the Company, the optionee shall have entered into any stockholders agreements or other agreements with the Company
and/or certain other of the Company’s stockholders relating to shares of the Stock. The delivery of certificates representing the shares of Stock (or the transfer to the optionee on the records of the Company with respect to uncertificated
Stock) to be purchased pursuant to the exercise of a Stock Option will be contingent upon receipt from the optionee (or a purchaser acting in his or her stead in accordance with the provisions of the Stock Option) by the Company of the full purchase
price for such shares and the fulfillment of any other requirements contained in the Option Award Agreement or applicable provisions of laws. In the event an optionee chooses to pay the purchase price by previously-owned shares of Stock through the
attestation method, the number of shares of Stock transferred to the optionee upon the exercise of the Stock Option shall be net of the number of shares attested to. 
 (b) Annual Limit on Incentive Stock Options. To the extent required for “incentive stock option” treatment under Section 422 of the Code, the aggregate Fair Market Value (determined
as of the time of grant) of the shares of Stock with respect to which Incentive Stock Options granted under the Plan and any other plan of the Company or its parent and any Subsidiary that become exercisable for the first time by an optionee during
any calendar year shall not exceed $100,000 or such other limit as may be in effect from time to time under Section 422 of the Code. To the extent that any Stock Option exceeds this limit, it shall constitute a Non-Qualified Stock Option.

 SECTION 6. RESTRICTED STOCK AWARDS 
 (a) Nature of Restricted Stock Awards. The Committee may, in its sole discretion, grant (or sell at par value or such other purchase price determined by the Committee) to an eligible person under
Section 4 hereof a Restricted Stock Award under the Plan. The Committee shall determine the restrictions and conditions applicable to each Restricted Stock Award at the time of grant. Conditions may be based on continuing employment (or other
Service Relationship), achievement of pre-established performance goals and objectives and/or such other criteria as the Committee may determine. The grant of a Restricted Stock Award is contingent on the grantee executing a Restricted Stock Award
Agreement. The terms and conditions of each such Award Agreement shall be determined by the Committee, and such terms and conditions may differ among individual Awards and grantees, all of whom must be eligible persons under Section 4 hereof.


  
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 (b) Rights as a Stockholder. Upon execution of a Restricted Stock Award Agreement and
payment of any applicable purchase price, a grantee of Restricted Stock shall be considered the record owner of and shall be entitled to vote the Shares of Restricted Stock if, and to the extent, such Shares are entitled to voting rights, subject to
such conditions contained in the Restricted Stock Award Agreement. The grantee shall be entitled to receive all dividends and any other distributions declared on the Shares; provided, however, that the Company is under no duty to
declare any such dividends or to make any such distribution. The Restricted Stock Award Agreement may require or permit the immediate payment, waiver, deferral or investment of dividends paid on the Restricted Stock. Unless the Committee shall
otherwise determine, certificates evidencing the Restricted Stock shall remain in the possession of the Company until such Restricted Stock is vested as provided in subsection (d) below of this Section, and the grantee shall be required, as a
condition of the grant, to deliver to the Company a stock power endorsed in blank and such other instruments of transfer as the Committee may prescribe. 
 (c) Restrictions. Restricted Stock may not be sold, assigned, transferred, pledged or otherwise encumbered or disposed of except as specifically provided herein or in the Restricted Stock Award
Agreement. Except as may otherwise be provided by the Committee either in the Award Agreement or, subject to Section 12 below, in writing after the Award Agreement is issued, if any, if a grantee’s employment (or other Service
Relationship) with the Company and any Subsidiary terminates, the Company or its assigns shall have the right, as may be specified in the relevant instrument, to repurchase some or all of the Shares subject to the Award at such purchase price as is
set forth in the Restricted Stock Award Agreement. 
 (d) Vesting of Restricted Stock. The Committee at the time of grant
shall specify the date or dates and/or the attainment of pre-established performance goals, objectives and other conditions on which the substantial risk of forfeiture imposed shall lapse and the Restricted Stock shall become vested, subject to such
further rights of the Company or its assigns as may be specified in the Restricted Stock Award Agreement. 
 SECTION 7. UNRESTRICTED STOCK
AWARDS 
 The Committee may, in its sole discretion, grant (or sell at par value or such other purchase price determined by
the Committee) to an eligible person under Section 4 hereof an Unrestricted Stock Award under the Plan. Unrestricted Stock Awards may be granted in respect of past services or other valid consideration, or in lieu of cash compensation due to
such grantee. 
 SECTION 8. RESTRICTED STOCK UNITS 
 (a) Nature of Restricted Stock Units. The Committee shall determine the restrictions and conditions applicable to each Restricted Stock Unit at the time of grant. Vesting conditions may be based on
continuing employment (or other Service Relationship), achievement of pre-established performance goals and objectives and/or other such criteria as the Committee may determine. The grant of Restricted Stock Unit(s) is contingent on the grantee
executing a Restricted Stock Unit Award Agreement. The terms and conditions of each such Award Agreement shall be determined by the Committee and may differ among individual Awards and grantees. On or promptly following the vesting date or dates
applicable to any Restricted Stock Unit, but in no event later than March 15 of the year following the year in which such vesting occurs, such Restricted Stock Unit(s), shall be settled in the form of cash or shares of Stock, as specified in
the Award Agreement. 

  
 12 









 (b) Rights as a Stockholder. A grantee shall have the rights of a stockholder only as
to shares of Stock, if any, acquired upon settlement of a Restricted Stock Unit. A grantee shall not be deemed to have acquired any such shares unless and until a Restricted Stock Unit shall have been settled in Stock pursuant to the terms hereof,
the Company shall have issued and delivered a certificate representing the shares to the grantee, and the grantee’s name shall have been entered in the books of the Company as a stockholder. 

(c) Termination. Except as may otherwise be provided by the Committee either in the Award Agreement or in writing after the Award
Agreement is issued, a grantee’s right in all Restricted Stock Units that have not vested shall automatically terminate upon the grantee’s termination of employment (or cessation of Service Relationship) with the Company and any Subsidiary
for any reason. 
 SECTION 9. TRANSFER RESTRICTIONS; COMPANY RIGHT OF FIRST REFUSAL; COMPANY REPURCHASE RIGHTS 

(a) Restrictions on Transfer. 
 (i) Non-Transferability of Stock Options. No Stock Option shall be transferable by the optionee otherwise than by will or by the laws of descent and distribution and all Stock Options shall be
exercisable, during the optionee’s lifetime, only by the optionee, or by the optionee’s legal representative or guardian in the event of the optionee’s incapacity. Notwithstanding the foregoing, the Committee, in its sole discretion,
may provide in the Award Agreement regarding a given Stock Option that the optionee may transfer, without consideration for the transfer, his or her Non-Qualified Stock Options to members of his or her immediate family, to trusts for the benefit of
such family members, or to partnerships in which such family members are the only partners, provided that the transferee agrees in writing with the Company to be bound by all of the terms and conditions of this Plan and the applicable Option.

 (ii) Issued Shares. No Issued Shares shall be sold, assigned, transferred, pledged, hypothecated, given away or in any
other manner disposed of or encumbered, whether voluntarily or by operation of law, unless (i) such transfer is in compliance with the terms of the applicable Award Agreement, all applicable securities laws (including, without limitation, the
Securities Act), and with the terms and conditions of this Section 9, (ii) such transfer does not cause the Company to become subject to the reporting requirements of the Exchange Act, and (iii) the transferee consents in writing to
be bound by the provisions of the Plan, including this Section 9. In connection with any proposed transfer, the Committee may require the transferor to provide at the transferor’s own expense an opinion of counsel to the transferor,
satisfactory to the Committee, that such transfer is in compliance with all foreign, federal and state securities laws (including, without limitation, the Securities Act). Any attempted disposition of Issued Shares not in accordance with the terms
and conditions of this Section 9 shall be null and void, and the Company shall not reflect on its records any change in record ownership of any Issued Shares as a result of any such disposition, shall otherwise refuse to recognize any such
disposition and shall not in any way give effect to any such disposition of Issued Shares. Subject 

  
 13 









 
to the foregoing general provisions, and unless otherwise provided in the applicable Award Agreement, Issued Shares may be transferred pursuant to the following specific terms and conditions
(provided that with respect to any transfer of Restricted Stock, all vesting and forfeiture provisions shall continue to apply only with respect to the original recipient): 

(A) Transfers to Permitted Transferees. The Holder may sell, assign, transfer or give away any or all of the Issued
Shares to Permitted Transferees; provided, however, that following such sale, assignment, transfer or gift, such Issued Shares shall continue to be subject to the terms of this Plan (including this Section 9) and such Permitted
Transferee(s) shall, as a condition to any such transfer, deliver a written acknowledgment to that effect to the Company. Notwithstanding the foregoing, the Holder may not sell, assign, transfer or give any or all of the Issued Shares to any Person
whom the Company reasonably determines is a direct competitor or a potential competitor of the Company or any of its Subsidiaries. 
 (B) Transfers Upon Death. Upon the death of the Holder, any Issued Shares then held by the Holder at the time of such death and any Issued Shares acquired thereafter by the Holder’s legal
representative shall be subject to the provisions of this Plan, and the Holder’s estate, executors, administrators, personal representatives, heirs, legatees and distributees shall be obligated to convey such Issued Shares to the Company or its
assigns under the terms contemplated hereby. 
 (b) Right of First Refusal. In the event that a Holder desires at any time
to sell or otherwise transfer all or any part of such Holder’s Issued Shares (other than shares of Restricted Stock which by their terms are not transferrable), the Holder first shall give written notice to the Company of the Holder’s
intention to make such transfer. Such notice shall state the number of Issued Shares which the Holder proposes to sell (the “Offered Shares”), the price and the terms at which the proposed sale is to be made and the name and address of the
proposed transferee. At any time within 30 days after the receipt of such notice by the Company, the Company or its assigns may elect to purchase all or any portion of the Offered Shares at the price and on the terms offered by the proposed
transferee and specified in the notice. The Company or its assigns shall exercise this right by mailing or delivering written notice to the Holder within the foregoing 30-day period. If the Company or its assigns elect to exercise its purchase
rights under this Section 9(b), the closing for such purchase shall, in any event, take place within 45 days after the receipt by the Company of the initial notice from the Holder. In the event that the Company or its assigns do not elect to
exercise such purchase right, or in the event that the Company or its assigns do not pay the full purchase price within such 45-day period, the Holder may, within 60 days thereafter, sell the Offered Shares to the proposed transferee and at the same
price and on the same terms as specified in the Holder’s notice. Any Shares purchased by such proposed transferee shall no longer be subject to the terms of the Plan. Any Shares not sold to the proposed transferee shall remain subject to the
Plan. If the Holder is a party to any stockholders agreements or other agreements with the Company and/or certain other of the Company’s stockholders relating to shares of the Stock, (i) the transferring Holder shall comply with the
requirements of such stockholders agreements or other agreements relating to any proposed transfer of the Offered Shares, and (ii) any proposed transferee that purchases Offered Shares shall enter into such stockholders agreements or other
agreements with the Company and/or certain other of the Company’s stockholders relating to the Offered Shares on the same terms and in the same capacity as the transferring Holder. 

  
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 (c) Company’s Right of Repurchase. 

(i) Right of Repurchase for Option Shares. The Company or its assigns shall have the right and option upon a Repurchase Event to
repurchase from a Holder of Option Shares some or all (as determined by the Company) of the Option Shares held or subsequently acquired upon exercise of a Stock Option by such Holder at the price per share specified below. Such repurchase right may
be exercised by the Company within the later of (A) six months following the date of such Repurchase Event or (B) seven months after the acquisition of such Option Shares upon exercise of a Stock Option (the “Option Shares Repurchase
Period”). The “Option Shares Repurchase Price” shall be equal to the Fair Market Value of the Option Shares, determined as of the date the Committee elects to exercise its repurchase rights in connection with a Repurchase Event.

 (ii) Right of Repurchase With Respect to Restricted Stock and Shares issued pursuant to an Unrestricted Stock Award or
Restricted Stock Unit Award. Unless otherwise set forth in the agreement entered into by the recipient and the Company in connection with a Restricted Stock Award, Unrestricted Stock Award or Restricted Stock Unit Award, the Company or its
assigns shall have the right and option upon a Repurchase Event to repurchase from a Holder of Issued Shares received pursuant to a Restricted Stock Award, Unrestricted Stock Award or Restricted Stock Unit Award some or all (as determined by the
Company) of such Issued Shares at the price per share specified below. In addition, upon a Termination Event, the Company or its assigns shall have the right and option to repurchase from a Holder of Issued Shares received pursuant to a Restricted
Stock Award any Issued Shares which have not vested as of the Termination Event. Such repurchase right may be exercised by the Company within six months following the date of such Repurchase Event or Termination Event as applicable (the
“Non-Option Shares Repurchase Period”). The “Non-Option Shares Repurchase Price” shall be (i) in the case of Issued Shares which are vested as of the date of the Repurchase Event, the Fair Market Value of such Issued Shares
as of the date the Company elects to exercise its repurchase rights in connection with a Repurchase Event and (ii) in the case of Issued Shares which have not vested as of the date of the Repurchase Event or Termination Event (as applicable),
the lower of the original per share purchase price paid by the recipient subject to adjustment as provided in Section 3(b) or the current Fair Market Value of such Issued Shares as of the date the Company elects to exercise its repurchase
rights in connection with a Repurchase Event or Termination Event (as applicable). 
 (iii) Procedure. Any repurchase
right of the Company shall be exercised by the Company or its assigns by giving the Holder written notice on or before the last day of the Option Shares Repurchase Period or Non-Option Shares Repurchase Period, as applicable, of its intention to
exercise such repurchase right. Upon such notification, the Holder shall promptly surrender to the Company, free and clear of any liens or encumbrances, any certificates representing the Shares being purchased, together with a duly executed stock
power for the transfer of such Shares to the Company or the Company’s assignee or assignees. Upon the Company’s or its assignee’s receipt of the certificates from the Holder, the Company or its assignee or assignees shall deliver to
him, her or them a check for the Option Shares Repurchase 

  
 15 









 
Price or the Non-Option Shares Repurchase Price, as applicable; provided, however, that the Company may pay the Option Shares Repurchase Price or Non-Option Shares Repurchase Price, as
applicable, by offsetting and canceling any indebtedness then owed by the Holder to the Company. 
 (d) Drag Along Right.
In the event the holders of a majority of the Company’s equity securities then outstanding (the “Majority Shareholders”) determine to enter into a Sale Event in a bona fide negotiated transaction (a “Sale”), with any
non-Affiliate of the Company or any majority shareholder (in each case, the “Buyer”), a Holder of Issued Shares, including any Permitted Transferees, shall be obligated to and shall upon the written request of the Majority Shareholders:
(a) sell, transfer and deliver, or cause to be sold, transferred and delivered, to the Buyer, his or her Issued Shares (including for this purpose all of such Holder’s or his or her Permitted Transferee’s Issued Shares that presently
or as a result of any such transaction may be acquired upon the exercise of an Option (following the payment of the exercise price therefor)) on substantially the same terms applicable to the Majority Shareholders (with appropriate adjustments to
reflect the conversion of convertible securities, the redemption of redeemable securities and the exercise of exercisable securities as well as the relative preferences and priorities of preferred stock); and (b) execute and deliver such
instruments of conveyance and transfer and take such other action, including voting such Issued Shares in favor of any Sale proposed by the Majority Shareholders and executing any purchase agreements, merger agreements, indemnity agreements, escrow
agreements or related documents as the Majority Shareholders or the Buyer may reasonably require in order to carry out the terms and provisions of this Section 9(d). 
 (e) Escrow Arrangement. 
 (i) Escrow. In order to carry out the
provisions of Sections 9(b), (c), and (d) of this Agreement more effectively, the Company shall hold any Issued Shares in escrow together with separate stock powers executed by the Holder in blank for transfer, and any Permitted Transferee
shall, as an additional condition to any transfer of Issued Shares, execute a like stock power as to such Issued Shares. The Company shall not dispose of the Issued Shares except as otherwise provided in this Agreement. In the event of any
repurchase by the Company (or any of its assigns), the Company is hereby authorized by the Holder and any Permitted Transferee, as the Holder’s and each such Permitted Transferee’s attorney-in-fact, to date and complete the stock powers
necessary for the transfer of the Issued Shares being purchased and to transfer such Issued Shares in accordance with the terms hereof. At such time as any Issued Shares are no longer subject to the Company’s repurchase, first refusal and drag
along rights, the Company shall, at the written request of the Holder, deliver to the Holder (or the relevant Permitted Transferee) a certificate representing such Issued Shares with the balance of the Issued Shares to be held in escrow pursuant to
this Section 9(e). 
 (ii) Remedy. Without limitation of any other provision of this Agreement or other rights, in
the event that a Holder, any Permitted Transferees or any other Person is required to sell a Holder’s Issued Shares pursuant to the provisions of Sections 9(b), (c), or (d) hereof and in the further event that he or she refuses or for any
reason fails to deliver to the Company or its designated purchaser of such Issued Shares the certificate or certificates evidencing such Issued Shares together with a related stock power, the Company or such designated purchaser may


  
 16 









 
deposit the applicable purchase price for such Issued Shares with a bank designated by the Company, or with the Company’s independent public accounting firm, as agent or trustee, or in
escrow, for such Holder, any Permitted Transferees or other Person, to be held by such bank or accounting firm for the benefit of and for delivery to him, her, them or it, and/or, in its discretion, pay such purchase price by offsetting any
indebtedness then owed by such Holder as provided above. Upon any such deposit and/or offset by the Company or its designated purchaser of such amount and upon notice to the Person who was required to sell the Issued Shares to be sold pursuant to
the provisions of Sections 9(b), (c), or (d), such Issued Shares shall at such time be deemed to have been sold, assigned, transferred and conveyed to such purchaser, such Holder shall have no further rights thereto (other than the right to withdraw
the payment thereof held in escrow, if applicable), and the Company shall record such transfer in its stock transfer book or in any appropriate manner. 
 (f) Lockup Provision. A Holder agrees, if requested by the Company and any underwriter engaged by the Company, not to sell or otherwise transfer or dispose of any Issued Shares (including,
without limitation, pursuant to Rule 144 under the Securities Act) held by him or her for such period following the effective date of any registration statement of the Company filed under the Securities Act as the Company or such underwriter shall
specify reasonably and in good faith. If requested by the underwriter engaged by the Company, each Holder shall execute a separate letter reflecting the agreement set forth in this Section 9(f). 

(g) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reclassification, stock
dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for a different number or kind of shares of the Company’s Stock, the
restrictions contained in this Section 9 shall apply with equal force to additional and/or substitute securities, if any, received by Holder in exchange for, or by virtue of his or her ownership of, Issued Shares. 

(h) Termination. The terms and provisions of Section 9(b), Section 9(c) (except for the Company’s right to
repurchase unvested Restricted Stock Awards upon a Termination Event) and Section 9(d) shall terminate upon the closing of the Company’s Initial Public Offering or upon consummation of any Sale Event, in either case as a result of which
shares of the Company (or a successor entity) of the same class as the Issued Shares are registered under Section 12 of the Exchange Act and publicly-traded on NASDAQ or any national security exchange. 

SECTION 10. TAX WITHHOLDING 
 (a) Payment by Grantee. Each grantee shall, no later than the date as of which the value of an Award or of any Stock or other amounts received thereunder first becomes includable in the gross
income of the grantee for Federal income tax purposes, pay to the Company, or make arrangements satisfactory to the Committee regarding payment of, any Federal, state, or local taxes of any kind required by law to be withheld by the Company with
respect to such income. The Company and any Subsidiary shall, to the extent permitted by law, have the right to deduct any such taxes from any payment of any kind otherwise due to the grantee. The Company’s obligation to deliver stock
certificates (or evidence of book entry) to any grantee is subject to and conditioned on any such tax withholding obligations being satisfied by the grantee. 

  
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 (b) Payment in Stock. Subject to approval by the Committee, the Company’s
minimum required tax withholding obligation may be satisfied, in whole or in part, by the Company withholding from shares of Stock to be issued pursuant to any Award a number of shares with an aggregate Fair Market Value (as of the date the
withholding is effected) that would satisfy the minimum withholding amount due. 
 SECTION 11.
SECTION 409A AWARDS. 
 To the extent that any Award is determined to constitute “nonqualified deferred
compensation” within the meaning of Section 409A (a “409A Award”), the Award shall be subject to such additional rules and requirements as specified by the Committee from time to time in order to comply with Section 409A. In
this regard, if any amount under a 409A Award is payable upon a “separation from service” (within the meaning of Section 409A) to a grantee who is considered a “specified employee” (within the meaning of Section 409A),
then no such payment shall be made prior to the date that is the earlier of (i) six months and one day after the grantee’s separation from service, or (ii) the grantee’s death, but only to the extent such delay is necessary to
prevent such payment from being subject to interest, penalties and/or additional tax imposed pursuant to Section 409A. 
 SECTION 12.
AMENDMENTS AND TERMINATION 
 The Board may, at any time, amend or discontinue the Plan and the Committee may, at any
time, amend or cancel any outstanding Award for the purpose of satisfying changes in law or for any other lawful purpose), but no such action shall adversely affect rights under any outstanding Award without the consent of the holder of the Award.
The Committee may exercise its discretion to reduce the exercise price of outstanding Stock Options or effect repricing through cancellation of outstanding Awards and by granting such holders new Awards in replacement of the cancelled Awards. To the
extent determined by the Committee to be required either by the Code to ensure that Incentive Stock Options granted under the Plan are qualified under Section 422 of the Code or otherwise, Plan amendments shall be subject to approval by the
Company stockholders entitled to vote at a meeting of stockholders. Nothing in this Section 12 shall limit the Board’s or Committee’s authority to take any action permitted pursuant to Section 3(c). 

SECTION 13. STATUS OF PLAN 
 With respect to the portion of any Award that has not been exercised and any payments in cash, Stock or other consideration not received by a grantee, a grantee shall have no rights greater than those of
a general creditor of the Company unless the Committee shall otherwise expressly so determine in connection with any Award or Awards. 

  
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 SECTION 14. GENERAL PROVISIONS 

(a) No Distribution; Compliance with Legal Requirements. The Committee may require each person acquiring Stock pursuant to an
Award to represent to and agree with the Company in writing that such person is acquiring the shares of Stock without a view to distribution thereof. No shares of Stock shall be issued pursuant to an Award until all applicable securities law and
other legal and stock exchange or similar requirements have been satisfied. The Committee may require the placing of such stop-orders and restrictive legends on certificates for Stock and Awards as it deems appropriate. 

(b) Delivery of Stock Certificates. Stock certificates to grantees under the Plan shall be deemed delivered for all purposes when
the Company or a stock transfer agent of the Company shall have mailed such certificates in the United States mail, addressed to the grantee, at the grantee’s last known address on file with the Company; provided that stock certificates to be
held in escrow pursuant to Section 9(e) of the Plan shall be deemed delivered when the Company shall have recorded the issuance in its records. Uncertificated Stock shall be deemed delivered for all purposes when the Company or a Stock transfer
agent of the Company shall have given to the grantee by electronic mail (with proof of receipt) or by United States mail, addressed to the grantee, at the grantee’s last known address on file with the Company, notice of issuance and recorded
the issuance in its records (which may include electronic “book entry” records). 
 (c) No Employment
Rights. The adoption of the Plan and the grant of Awards do not confer upon any Person any right to continued employment or Service Relationship with the Company or any Subsidiary. 

(d) Trading Policy Restrictions. Option exercises and other Awards under the Plan shall be subject to the Company’s insider
trading policy-related restrictions, terms and conditions as may be established by the Committee, or in accordance with policies set by the Committee, from time to time. 
 (e) Designation of Beneficiary. Each grantee to whom an Award has been made under the Plan may designate a beneficiary or beneficiaries to exercise any Award on or after the grantee’s death or
receive any payment under any Award payable on or after the grantee’s death. Any such designation shall be on a form provided for that purpose by the Committee and shall not be effective until received by the Committee. If no beneficiary has
been designated by a deceased grantee, or if the designated beneficiaries have predeceased the grantee, the beneficiary shall be the grantee’s estate. 
 (f) Legend. Any certificate(s) representing the Issued Shares shall carry substantially the following legend (and with respect to uncertificated Stock, the book entries evidencing such shares shall
contain the following notation): 
 The transferability of this certificate and the shares of stock represented hereby are
subject to the restrictions, terms and conditions (including repurchase and restrictions against transfers) contained in the bluebird bio, Inc. 2010 Stock Option and Grant Plan and any agreement entered into thereunder by and between the company and
the holder of this certificate (a copy of which is available at the offices of the company for examination). 

  
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 SECTION 15. EFFECTIVE DATE OF PLAN 

The Plan shall become effective upon adoption by the Board and shall be approved by stockholders in accordance with applicable state law
and the Company’s articles of incorporation and bylaws within 12 months thereafter. Subject to such approval by stockholders and to the requirement that no Stock may be issued hereunder prior to such approval, Stock Options and other Awards may
be granted hereunder on and after adoption of the Plan by the Board. No grants of Stock Options and other Awards may be made hereunder after the tenth anniversary of the Effective Date. 
 SECTION 16. GOVERNING LAW 
 This Plan, all Awards and any controversy
arising out of or relating to this Plan and all Awards shall be governed by and construed in accordance with the General Corporation Law of the State of Delaware as to matters within the scope thereof, and as to all other matters shall be governed
by and construed in accordance with the internal laws of the Commonwealth of Massachusetts, without regard to conflict of law principles that would result in the application of any law other than the law of the Commonwealth of Massachusetts.

 DATE ADOPTED BY THE BOARD OF DIRECTORS: September 15, 2010 
 DATE APPROVED BY THE STOCKHOLDERS: October 4, 2010 

  
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 INCENTIVE STOCK OPTION AGREEMENT 

UNDER THE BLUEBIRD BIO, INC. 
 2010 STOCK OPTION AND GRANT PLAN 
  

			
	Name of Optionee:	 	                         (the
“Optionee”)
		
	No. of Underlying Shares:	 	             Shares of Common Stock
		
	Grant Date:	 	__________
		
	Vesting Commencement Date:	 	                         (the “Vesting
Commencement Date”)
		
	Expiration Date:	 	                         (the “Expiration
Date”)
		
	Option Exercise Price/Share:	 	$                       (the “Option Exercise
Price”)

 Pursuant to the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”), bluebird bio,
Inc., a Delaware corporation (together with any successor thereto, the “Company”), hereby grants to the Optionee, who is an employee of the Company or any of its Subsidiaries, an option (the “Stock Option”) to purchase on or
prior to the Expiration Date, or such earlier date as is specified herein, all or any part of the number of shares of Common Stock, par value $0.01 per share (“Common Stock”), of the Company indicated above (the “Underlying
Shares,” and such shares once issued shall be referred to as the “Option Shares”), at the Option Exercise Price per share, subject to the terms and conditions set forth in this Incentive Stock Option Agreement (this
“Agreement”) and in the Plan. This Stock Option is intended to qualify as an “incentive stock option” as defined in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time (the “Code”). To
the extent that any portion of the Stock Option does not so qualify, it shall be deemed a non-qualified stock option. 
 All
capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Plan. 
 1.
Vesting, Exercisability and Termination. 
 (a) No portion of this Stock Option may be exercised until such portion shall
have vested and become exercisable. 
 (b) Except as set forth below, and subject to the determination of the Committee in its
sole discretion to accelerate the vesting schedule hereunder, this Stock Option shall be vested and exercisable with respect to the Underlying Shares on the respective dates indicated below: 

(i) All Underlying Shares shall initially be unvested and unexercisable. 

  
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 (ii) [25] percent of the Underlying Shares shall vest and become exercisable
on the [first] anniversary of the Vesting Commencement Date; provided that the Optionee continues to have a Service Relationship with the Company at such time. 
 (iii) Thereafter, the remaining [75] percent of the Underlying Shares shall vest and become exercisable in [36] equal monthly installments at the end of each month following the first anniversary of the
Vesting Commencement Date, provided the Optionee continues to have a Service Relationship with the Company at such time. 

Notwithstanding anything herein to the contrary in the case of a Sale Event, this Stock Option shall be treated as provided in
Section 3(c) of the Plan. 
 (c) Termination. Except as may otherwise be provided by the Committee, if the
Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter terminate subject, in each
case to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If the
Optionee’s Service Relationship terminates by reason of such Optionee’s death or disability (as defined in Section 422(c) of the Code), this Stock Option may be exercised, to the extent exercisable on the date of such termination, by
the Optionee, the Optionee’s legal representative or legatee for a period of 12 months from the date of death or disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
disability (as defined in Section 422(c) of the Code), and unless otherwise determined by the Committee, this Stock Option may be exercised, to the extent exercisable on the date of termination, for a period of 90 days from the date of
termination or until the Expiration Date or other termination date, if earlier; provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately upon the date of such
termination. 
 For purposes hereof, the Committee’s determination of the reason for termination of the Optionee’s
Service Relationship shall be conclusive and binding on the Optionee and his or her representatives or legatees. Any portion of this Stock Option that is not exercisable on the date of termination of the Service Relationship shall terminate
immediately and be null and void. 
 (d) It is understood and intended that this Stock Option is intended to qualify as an
“incentive stock option” as defined in Section 422 of the Code to the extent permitted under applicable law. Accordingly, the Optionee understands that in order to obtain the benefits of an incentive stock option under
Section 422 of the Code, no sale or other disposition may be made of Option Shares for which incentive stock option treatment is desired within the one-year period beginning on the day after the day of the transfer of such Option Shares to him
or her, nor within the two-year period beginning on the day after Grant Date of this Stock Option and further that this Stock Option must be exercised within three months after termination of employment as an employee (or 12 months in the case of
death or disability) to qualify as an incentive stock option. If the Optionee disposes (whether by sale, gift, transfer or otherwise) of 

  
 2 








 
any such Option Shares within either of these periods, he or she will notify the Company within 30 days after such disposition. The Optionee also agrees to provide the Company with any
information concerning any such dispositions required by the Company for tax purposes. Further, to the extent the Underlying Shares and any other incentive stock options of the Optionee having an aggregate Fair Market Value in excess of $100,000
(determined as of the Grant Date) first become exercisable in any year, such options will not qualify as incentive stock options. 
 2. Exercise of Stock Option. 
 (a) The Optionee may exercise this Stock
Option only in the following manner: Prior to the Expiration Date, the Optionee may deliver a Stock Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some
or all of the Underlying Shares with respect to which this Stock Option is exercisable at the time of such notice. Such notice shall specify the number of Underlying Shares to be purchased. Payment of the purchase price may be made by one or more of
the methods described in Sections 5(a)(iv)(A), (B), (C) or (D) of the Plan, subject to the limitations contained in such Sections of the Plan, including the requirement that the Committee specifically approve in advance certain payment
methods. 
 (b) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock Option shall be exercisable
after the Expiration Date. 
 3. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Stock
Option shall be subject to and governed by all the terms and conditions of the Plan. 
 4. Transferability of Stock
Option. This Agreement is personal to the Optionee and is not transferable by the Optionee in any manner other than by will or by the laws of descent and distribution. The Stock Option may be exercised during the Optionee’s lifetime only by
the Optionee (or by the Optionee’s guardian or personal representative in the event of the Optionee’s incapacity). The Optionee may elect to designate a beneficiary by providing written notice of the name of such beneficiary to the
Company, and may revoke or change such designation at any time by filing written notice of revocation or change with the Company; such beneficiary may exercise the Optionee’s Stock Option in the event of the Optionee’s death to the extent
provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary predeceases the Optionee, the legal representative of the Optionee may exercise this Stock Option to the extent provided herein in the event of the
Optionee’s death. 
 5. Restrictions on Transfer of Option Shares. The Option Shares acquired upon exercise of the
Stock Option shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan. 
 6. Miscellaneous Provisions. 
 (a) Equitable Relief. The parties
hereto agree and declare that legal remedies may be inadequate to enforce the provisions of this Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement.


  
 3 








 (b) Adjustments for Changes in Capital Structure. If, as a result of any
reorganization, recapitalization, reincorporation, reclassification, stock dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for
a different number or kind of shares of the Company’s stock, the restrictions contained in this Agreement shall apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of
his or her ownership of, Option Shares. 
 (c) Change and Modifications. This Agreement may not be orally changed,
modified or terminated, nor shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Optionee. 

(d) Governing Law. This Agreement shall be governed by and construed in accordance with the General Corporation Law of the State
of Delaware as to matters within the scope hereof, and as to all other matters shall be governed by and construed in accordance with the internal laws of the Commonwealth of Massachusetts, without regard to conflict of law principles that would
result in the application of any law other than the law of the Commonwealth of Massachusetts. 
 (e) Headings. The
headings are intended only for convenience in finding the subject matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 

(f) Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination
shall in no manner affect the legality or enforceability of any other provision hereof. 
 (g) Notices. All notices,
requests, consents and other communications shall be in writing and be deemed given when delivered personally, by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the
Company or the Optionee shall be addressed as set forth underneath their signatures below, or to such other address or addresses as may have been furnished by such party in writing to the other. 

(h) Benefit and Binding Effect. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their
respective successors, permitted assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all the rights of the Company hereunder to the extent of such assignment. 

(i) Counterparts. For the convenience of the parties and to facilitate execution, this Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 

  
 4 








 7. Dispute Resolution. 

(a) Except as provided below, any dispute arising out of or relating to the Plan or this Stock Option, this Agreement, or the breach,
termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the
“J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the arbitrators may be entered by any court having jurisdiction thereof. The place
of arbitration shall be Boston, MA. 
 (b) The arbitration shall commence within 60 days of the date on which a written demand
for arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to
three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The
Company, the Optionee, each party to the Agreement and any other holder of Stock issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This
Section 7 applies equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited
purpose of avoiding immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of
any United States District Court of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees not to assert, by way of motion, as a defense, or otherwise, in any such suit,
action or proceeding, any claim that it is not subject personally to the jurisdiction of the above named courts, that its property is exempt or immune from attachment or execution (except as protected by applicable law), that the suit, action or
proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court, and (iii) hereby waives and agrees not to
seek any review by any court of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be
given. Each Party agrees that its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or
proceeding may be enforced in other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 

[SIGNATURE PAGE FOLLOWS] 

  
 5 








 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	BLUEBIRD BIO, INC.
		
	By:	 	 
		 	Name:
		 	Title:
		
		 	Address:
		
		 	 840 Memorial Drive

Cambridge, MA 02139



 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that the Stock Option granted hereby is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS IN SECTION 7 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 
  

	
	OPTIONEE:
	
	  
	Name:
	
	Address:
	
	 
	
	 
	
	 


 [SPOUSE’S CONSENT 
 I acknowledge that I have read the 
 foregoing Incentive Stock Option Agreement 

and understand the contents thereof. 

                         
                                         
  ] 







 
	
	DESIGNATED BENEFICIARY:
	
	  
	


  

	
	Beneficiary’s Address:
	
	  
	
	  
	
	  









 Appendix A 

STOCK OPTION EXERCISE NOTICE 
 BLUEBIRD BIO, INC. 
 Attention:
[                            ] 
 840 Memorial Drive 
 Cambridge, MA 02139 

Pursuant to the terms of the stock option agreement between the undersigned and bluebird bio, Inc. (the “Company”) dated
                     (the “Agreement”) under the bluebird bio, Inc. 2010 Stock Option and Grant Plan, I, [Insert Name]
                    , hereby [Circle One] partially/fully exercise such option by including herein payment in the amount of
$                     representing the purchase price for [Fill in number of Underlying Shares]
                     Underlying Shares. I have chosen the following form(s) of payment: 

 

	 	[  ]	1. Cash 

  

	 	[  ]	2. Certified or bank check payable to “bluebird bio, Inc.” 

  

	 	[  ]	3. Other (as referenced in the Agreement and described in the Plan (please describe)) 

                                   
                                         
                                         
                                         
                                         
                  . 
 In
connection with my exercise of the option as set forth above, I hereby represent and warrant to the Company as follows: 
 (i) I am purchasing the Underlying Shares for my own account for investment only, and not for resale or with a view to the distribution thereof. 

(ii) I have had such an opportunity as I have deemed adequate to obtain from the Company such information as is necessary
to permit me to evaluate the merits and risks of my investment in the Company and have consulted with my own advisers with respect to my investment in the Company. 

(iii) I have sufficient experience in business, financial and investment matters to be able to evaluate the risks involved
in the purchase of the Underlying Shares and to make an informed investment decision with respect to such purchase. 
 (iv) I can afford a complete loss of the value of the Option Shares and am able to bear the economic risk of holding such Option Shares for an indefinite period of time. 

(v) I understand that the Option Shares may not be registered under the Securities Act of 1933 (it being understood that
the Option Shares are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold or otherwise transferred or disposed of in the absence of
an effective registration statement under the Securities Act 







 
of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing
Option Shares will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Option Shares will include similar restrictive notations. 

 

	
	Sincerely yours,
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  









 EARLY EXERCISE 
 INCENTIVE STOCK OPTION AGREEMENT 
 UNDER THE BLUEBIRD BIO, INC.

 2010 STOCK OPTION AND GRANT PLAN 
  

			
	Name of Optionee:	 	                         (the
“Optionee”)
		
	No. of Option Shares:	 	             Shares of Common Stock
		
	Grant Date:	 	__________
		
	Vesting Commencement Date:	 	                         (the “Vesting
Commencement Date”)
		
	Expiration Date:	 	                         (the “Expiration
Date”)
		
	Option Exercise Price/Share:	 	$                       (the “Option Exercise
Price”)

 Pursuant to the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”), bluebird bio,
Inc., a Delaware corporation (together with any successor thereto, the “Company”), hereby grants to the Optionee, who is an employee of the Company or any of its Subsidiaries, an option (the “Stock Option”) to purchase on or
prior to the Expiration Date, or such earlier date as is specified herein, all or any part of the number of shares of Common Stock, par value $0.01 per share (“Common Stock”), of the Company indicated above (the “Option Shares”),
at the Option Exercise Price per share, subject to the terms and conditions set forth in this Early Exercise Incentive Stock Option Agreement (this “Agreement”) and in the Plan. This Stock Option is intended to qualify as an
“incentive stock option” as defined in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time (the “Code”). To the extent that any portion of the Stock Option does not so qualify, it shall be
deemed a non-qualified stock option. 
 All capitalized terms used herein and not otherwise defined shall have the respective
meanings set forth in the Plan. 
 1. Vesting, Exercisability and Termination. 

(a) This Stock Option shall be immediately exercisable, regardless of whether the Option Shares are vested. 

(b) Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting
schedule hereunder, the Option Shares shall be vested on the respective dates indicated below: 
 (i) All Option
Shares shall initially be unvested. 
 (ii) [25] percent of the Option Shares shall vest on the [first]
anniversary of the Vesting Commencement Date; provided that the Optionee continues to have a Service Relationship with the Company at such time. 

  
 1 








 (iii) Thereafter, the remaining [75] percent of the Option Shares shall vest
in [36] equal monthly installments at the end of each month following the first anniversary of the Vesting Commencement Date, provided the Optionee continues to have a Service Relationship with the Company at such time. 

Notwithstanding anything herein to the contrary in the case of a Sale Event, this Stock Option and the Option Shares shall be treated as
provided in Section 3(c) of the Plan. 
 (c) Termination. Except as may otherwise be provided by the Committee, if
the Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter terminate subject, in
each case to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If the
Optionee’s Service Relationship terminates by reason of such Optionee’s death or disability (as defined in Section 422(c) of the Code), this Stock Option may continue to be exercised, to the extent the Option Shares are vested on the
date of termination, by the Optionee, the Optionee’s legal representative or legatee for a period of 12 months from the date of death or disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
disability (as defined in Section 422(c) of the Code), and unless otherwise determined by the Committee, this Stock Option may continue to be exercised, to the extent the Option Shares are vested on the date of termination, for a period of 90
days from the date of termination or until the Expiration Date or other termination date, if earlier; provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately upon
the date of such termination[, such termination shall be treated as a “Repurchase Event” and the Company shall have the right to repurchase the Shares as set forth in Section 9(c) of the Plan]. 

For purposes hereof, the Committee’s determination of the reason for termination of the Optionee’s Service Relationship shall
be conclusive and binding on the Optionee and his or her representatives or legatees. Any portion of this Stock Option with respect to Option Shares that are not vested on the date of termination of the Service Relationship shall terminate
immediately and be null and void. 
 (d) It is understood and intended that this Stock Option is intended to qualify as an
“incentive stock option” as defined in Section 422 of the Code to the extent permitted under applicable law. Accordingly, the Optionee understands that in order to obtain the benefits of an incentive stock option under
Section 422 of the Code, no sale or other disposition may be made of Option Shares for which incentive stock option treatment is desired within the one-year period beginning on the day after the day of the transfer of such Option Shares to him
or her, nor within the two-year period beginning on the day after Grant Date of this Stock Option and further that this Stock Option must be exercised within three months after termination of employment as an employee (or 12 months in the case of
death or disability) to qualify as an incentive stock option. If the Optionee disposes (whether by sale, gift, transfer or otherwise) of 

  
 2 








 
any such Option Shares within either of these periods, he or she will notify the Company within 30 days after such disposition. The Optionee also agrees to provide the Company with any
information concerning any such dispositions required by the Company for tax purposes. Further, to the extent the Option Shares and any other incentive stock options of the Optionee having an aggregate Fair Market Value in excess of $100,000
(determined as of the Grant Date) first become exercisable in any year, such options will not qualify as incentive stock options. 
 2. Exercise of Stock Option. 
 (a) The Optionee may exercise this Stock
Option only in the following manner: Prior to the Expiration Date, the Optionee may deliver a Stock Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some
or all of the Option Shares. Such notice shall specify the number of Option Shares to be purchased. To the extent this Stock Option is only partially exercised, such exercise shall first be with respect to the Option Shares, if any, that have
previously vested, and then with respect to the Option Shares that will next vest, with the Option Shares that vest at the latest date being exercised last. Payment of the purchase price may be made by one or more of the methods described in
Sections 5(a)(iv)(A), (B), (C) or (D) of the Plan, subject to the limitations contained in such Sections of the Plan, including the requirement that the Committee specifically approve in advance certain payment methods. 

(b) In the event the Optionee exercises a portion of this Stock Option with respect to Option Shares that have not vested, the Optionee
shall also deliver a Restricted Stock Agreement covering such unvested Option Shares in the form of Appendix B hereto (the “Restricted Stock Agreement”) with the same vesting schedule for such Option Shares as set forth for such
Option Shares herein. 
 (c) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock Option shall be
exercisable after the Expiration Date. 
 3. Incorporation of Plan. Notwithstanding anything herein to the contrary, this
Stock Option shall be subject to and governed by all the terms and conditions of the Plan. 
 4. Transferability of Stock
Option. This Agreement is personal to the Optionee and is not transferable by the Optionee in any manner other than by will or by the laws of descent and distribution. The Stock Option may be exercised during the Optionee’s lifetime only by
the Optionee (or by the Optionee’s guardian or personal representative in the event of the Optionee’s incapacity). The Optionee may elect to designate a beneficiary by providing written notice of the name of such beneficiary to the
Company, and may revoke or change such designation at any time by filing written notice of revocation or change with the Company; such beneficiary may exercise the Optionee’s Stock Option in the event of the Optionee’s death to the extent
provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary predeceases the Optionee, the legal representative of the Optionee may exercise this Stock Option to the extent provided herein in the event of the
Optionee’s death. 
 5. Restrictions on Transfer of Option Shares. The Option Shares acquired upon exercise of the
Stock Option shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan and, if applicable, the Restricted Stock Agreement. 

  
 3 








 6. Miscellaneous Provisions. 

(a) Equitable Relief. The parties hereto agree and declare that legal remedies may be inadequate to enforce the provisions of this
Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement. 
 (b) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reincorporation, reclassification, stock dividend, stock split, reverse stock split or
other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for a different number or kind of shares of the Company’s stock, the restrictions contained in this Agreement shall
apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of his or her ownership of, Option Shares. 
 (c) Change and Modifications. This Agreement may not be orally changed, modified or terminated, nor shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified
or terminated only by an agreement in writing signed by the Company and the Optionee. 
 (d) Governing Law. This
Agreement shall be governed by and construed in accordance with the General Corporation Law of the State of Delaware as to matters within the scope hereof, and as to all other matters shall be governed by and construed in accordance with the
internal laws of the Commonwealth of Massachusetts, without regard to conflict of law principles that would result in the application of any law other than the law of the Commonwealth of Massachusetts. 

(e) Headings. The headings are intended only for convenience in finding the subject matter and do not constitute part of the text
of this Agreement and shall not be considered in the interpretation of this Agreement. 
 (f) Saving Clause. If any
provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination shall in no manner affect the legality or enforceability of any other provision hereof. 

(g) Notices. All notices, requests, consents and other communications shall be in writing and be deemed given when delivered
personally, by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the Company or the Optionee shall be addressed as set forth underneath their signatures below, or to
such other address or addresses as may have been furnished by such party in writing to the other. 
 (h) Benefit and Binding
Effect. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their respective successors, permitted assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee
shall become entitled to all the rights of the Company hereunder to the extent of such assignment. 

  
 4 








 (i) Counterparts. For the convenience of the parties and to facilitate execution,
this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 
 7. Dispute Resolution. 
 (a) Except as provided below, any dispute arising
out of or relating to the Plan or this Stock Option, this Agreement, or the breach, termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with
the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the “J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the
arbitrators may be entered by any court having jurisdiction thereof. The place of arbitration shall be Boston, MA. 
 (b) The
arbitration shall commence within 60 days of the date on which a written demand for arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by
each party and any third-party witnesses. In addition, each party may take up to three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the
arbitrator shall not have the power to order the answering of interrogatories or the response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days
before the date of the arbitration, the identity of all persons that may testify at the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The
arbitrator’s decision and award shall be made and delivered within six months of the selection of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator
shall not have power to award damages in excess of actual compensatory damages and shall not multiply actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 

(c) The Company, the Optionee, each party to the Agreement and any other holder of Stock issued pursuant to this Agreement (each, a
“Party”) covenants and agrees that such party will participate in the arbitration in good faith. This Section 7 applies equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of
temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited purpose of avoiding immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States District Court of competent jurisdiction for the purpose of enforcing the award or decision in any such
proceeding, (ii) hereby waives, and agrees not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the above named courts, that its
property is exempt or immune from attachment or execution (except as protected by applicable law), that the suit, action or 

  
 5 








 
proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such
court, and (iii) hereby waives and agrees not to seek any review by any court of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by
registered mail at the address to which notices are to be given. Each Party agrees that its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final
judgment against any Party in any such action, suit or proceeding may be enforced in other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction.

 [SIGNATURE PAGE FOLLOWS] 

  
 6 








 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	BLUEBIRD BIO, INC.
		
	By:	 	 
		 	Name:
		 	Title:
		
		 	Address:
		 	 840 Memorial Drive

Cambridge, MA 02139



 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that the Stock Option granted hereby is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS IN SECTION 7 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 
  

	
	OPTIONEE:
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  


 [SPOUSE’S CONSENT 
 I acknowledge that I have read the 
 foregoing Incentive Stock Option Agreement 

and understand the contents thereof. 

                         
                                         
      ] 







 
	
	DESIGNATED BENEFICIARY:
	
	  
	


  

	
	Beneficiary’s Address:
	
	  
	
	  
	
	  









 Appendix A 

STOCK OPTION EXERCISE NOTICE 
 BLUEBIRD BIO, INC. 
 Attention: Office Manager 

840 Memorial Drive 
 Cambridge, MA 02139

 Pursuant to the terms of the stock option agreement between the undersigned and bluebird bio, Inc. (the “Company”)
dated                      (the “Agreement”) under the bluebird bio, Inc. 2010 Stock Option and Grant Plan, I, [Insert Name]
                    , hereby [Circle One] partially/fully exercise such option by including herein payment in the amount of
$                     representing the purchase price for [Fill in number of Option Shares]
                     Option Shares. I have chosen the following form(s) of payment: 

 

	 	[  ]	1. Cash 

  

	 	[  ]	2. Certified or bank check payable to “bluebird bio, Inc.” 

  

	 	[  ]	3. Other (as referenced in the Agreement and described in the Plan (please describe)) 


                      
                                         
                                         
                                         
                   . 
 In
connection with my exercise of the option as set forth above, I hereby represent and warrant to the Company as follows: 
 (i) I am purchasing the Option Shares for my own account for investment only, and not for resale or with a view to the distribution thereof. 

(ii) I have had such an opportunity as I have deemed adequate to obtain from the Company such information as is necessary
to permit me to evaluate the merits and risks of my investment in the Company and have consulted with my own advisers with respect to my investment in the Company. 

(iii) I have sufficient experience in business, financial and investment matters to be able to evaluate the risks involved
in the purchase of the Option Shares and to make an informed investment decision with respect to such purchase. 

(iv) I can afford a complete loss of the value of the Option Shares and am able to bear the economic risk of holding such
Option Shares for an indefinite period of time. 
 (v) I understand that the Option Shares may not be registered
under the Securities Act of 1933 (it being understood that the Option Shares are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold
or otherwise transferred or disposed of in the absence of an effective registration statement under the Securities Act 







 
of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing
Option Shares will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Option Shares will include similar restrictive notations. 

(vi) To the extent required, I have executed and delivered to the Company the Restricted Stock Agreement attached as
Appendix B to the Agreement. 
  

	
	Sincerely yours,
	
	  
	Name:
	
	Address:
	
	  
	
	  









 Appendix B 

RESTRICTED STOCK AGREEMENT 







 NON-QUALIFIED STOCK OPTION AGREEMENT 

UNDER THE BLUEBIRD BIO, INC. 
 2010 STOCK OPTION AND GRANT PLAN 
  

			
	Name of Optionee:	 	                         (the
“Optionee”)
		
	No. of Underlying Shares:	 	             Shares of Common Stock
		
	Grant Date:	 	__________
		
	Vesting Commencement Date:	 	                         (the “Vesting
Commencement Date”)
		
	Expiration Date:	 	                         (the “Expiration
Date”)
		
	Option Exercise Price/Share:	 	$                       (the “Option Exercise
Price”)

 Pursuant to the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”), bluebird bio,
Inc., a Delaware corporation (together with any successor thereto, the “Company”), hereby grants to the Optionee, who is an officer, employee, director, Consultant or other key person of the Company or any of its Subsidiaries, an option
(the “Stock Option”) to purchase on or prior to the Expiration Date, or such earlier date as is specified herein, all or any part of the number of shares of Common Stock, par value $0.01 per share (“Common Stock”), of the Company
indicated above (the “Underlying Shares,” and such shares once issued shall be referred to as the “Option Shares”), at the Option Exercise Price per share, subject to the terms and conditions set forth in this Non-Qualified Stock
Option Agreement (this “Agreement”) and in the Plan. This Stock Option is not intended to qualify as an “incentive stock option” as defined in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time
(the “Code”). 
 All capitalized terms used herein and not otherwise defined shall have the respective meanings set
forth in the Plan. 
 1. Vesting, Exercisability and Termination. 

(a) No portion of this Stock Option may be exercised until such portion shall have vested and become exercisable. 

(b) Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting
schedule hereunder, this Stock Option shall be vested and exercisable with respect to the Underlying Shares on the respective dates indicated below: 
 (i) All Underlying Shares shall initially be unvested and unexercisable. 







 (ii) [25] percent of the Underlying Shares shall vest and become exercisable
on the [first] anniversary of the Vesting Commencement Date; provided that the Optionee continues to have a Service Relationship with the Company at such time. 
 (iii) Thereafter, the remaining [75] percent of the Underlying Shares shall vest and become exercisable in [36] equal monthly installments at the end of each month following the first anniversary of the
Vesting Commencement Date, provided the Optionee continues to have a Service Relationship with the Company at such time. 

Notwithstanding anything herein to the contrary in the case of a Sale Event, this Stock Option shall be treated as provided in
Section 3(c) of the Plan. 
 (c) Termination. Except as may otherwise be provided by the Committee, if the
Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter terminate subject, in each
case to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If the
Optionee’s Service Relationship terminates by reason of such Optionee’s death or disability (as defined in Section 422(c) of the Code), this Stock Option may be exercised, to the extent exercisable on the date of such termination, by
the Optionee, the Optionee’s legal representative or legatee for a period of 12 months from the date of death or disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
disability (as defined in Section 422(c) of the Code), and unless otherwise determined by the Committee, this Stock Option may be exercised, to the extent exercisable on the date of termination, for a period of 90 days from the date of
termination or until the Expiration Date or other termination date, if earlier; provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately upon the date of such
termination[, such termination shall be treated as a “Repurchase Event” and the Company shall have the right to repurchase the Shares as set forth in Section 9(c) of the Plan]. 

For purposes hereof, the Committee’s determination of the reason for termination of the Optionee’s Service Relationship shall
be conclusive and binding on the Optionee and his or her representatives or legatees and any Permitted Transferee. Any portion of this Stock Option that is not exercisable on the date of termination of the Service Relationship shall terminate
immediately and be null and void. 
 2. Exercise of Stock Option. 

(a) The Optionee may exercise this Stock Option only in the following manner: Prior to the Expiration Date, the Optionee may deliver a
Stock Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some or all of the Underlying Shares with respect to which this Stock Option is exercisable at the
time of such notice. Such notice shall specify the number of Underlying Shares to be purchased. Payment of the purchase price may be made by one or more of the methods described in Sections 5(a)(iv)(A), (B), (C), (D) or (E) of the Plan,
subject to the limitations contained in such Sections of the Plan, including the requirement that the Committee specifically approve in advance certain payment methods. 

  
 2 








 (b) Notwithstanding any other provision hereof or of the Plan, no portion of this Stock
Option shall be exercisable after the Expiration Date. 
 3. Incorporation of Plan. Notwithstanding anything herein to
the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan. 
 4.
Transferability of Stock Option. This Agreement is personal to the Optionee and is not transferable by the Optionee in any manner other than by will or by the laws of descent and distribution. The Stock Option may be exercised during the
Optionee’s lifetime only by the Optionee (or by the Optionee’s guardian or personal representative in the event of the Optionee’s incapacity). The Optionee may elect to designate a beneficiary by providing written notice of the name
of such beneficiary to the Company, and may revoke or change such designation at any time by filing written notice of revocation or change with the Company; such beneficiary may exercise the Optionee’s Stock Option in the event of the
Optionee’s death to the extent provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary predeceases the Optionee, the legal representative of the Optionee may exercise this Stock Option to the extent
provided herein in the event of the Optionee’s death. 
 5. Restrictions on Transfer of Option Shares. The Option
Shares acquired upon exercise of the Stock Option shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan. 

6. Miscellaneous Provisions. 
 (a) Equitable Relief. The parties hereto agree and declare that legal remedies may be inadequate to enforce the provisions of this Agreement and that equitable relief, including specific
performance and injunctive relief, may be used to enforce the provisions of this Agreement. 
 (b) Adjustments for Changes in
Capital Structure. If, as a result of any reorganization, recapitalization, reincorporation, reclassification, stock dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding shares of Common Stock
are increased or decreased or are exchanged for a different number or kind of shares of the Company’s stock, the restrictions contained in this Agreement shall apply with equal force to additional and/or substitute securities, if any, received
by the Optionee in exchange for, or by virtue of his or her ownership of, Option Shares. 
 (c) Change and Modifications.
This Agreement may not be orally changed, modified or terminated, nor shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the
Optionee. 

  
 3 








 (d) Governing Law. This Agreement shall be governed by and construed in accordance
with the General Corporation Law of the State of Delaware as to matters within the scope hereof, and as to all other matters shall be governed by and construed in accordance with the internal laws of the Commonwealth of Massachusetts, without regard
to conflict of law principles that would result in the application of any law other than the law of the Commonwealth of Massachusetts. 
 (e) Headings. The headings are intended only for convenience in finding the subject matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation
of this Agreement. 
 (f) Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or
unenforceable, such determination shall in no manner affect the legality or enforceability of any other provision hereof. 
 (g)
Notices. All notices, requests, consents and other communications shall be in writing and be deemed given when delivered personally, by telex or facsimile transmission or when received if mailed by first class registered or certified mail,
postage prepaid. Notices to the Company or the Optionee shall be addressed as set forth underneath their signatures below, or to such other address or addresses as may have been furnished by such party in writing to the other. 

(h) Benefit and Binding Effect. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their
respective successors, permitted assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all the rights of the Company hereunder to the extent of such assignment. 

(i) Counterparts. For the convenience of the parties and to facilitate execution, this Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 
 7.
Dispute Resolution. 
 (a) Except as provided below, any dispute arising out of or relating to the Plan or this Stock
Option, this Agreement, or the breach, termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive
Arbitration Rules and Procedures (the “J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the arbitrators may be entered by any court
having jurisdiction thereof. The place of arbitration shall be Boston, MA. 
 (b) The arbitration shall commence within 60 days
of the date on which a written demand for arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses.
In addition, each party may take up to three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order
the answering of interrogatories or the response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business


  
 4 








 
days before the date of the arbitration, the identity of all persons that may testify at the arbitration and a copy of all documents that may be introduced at the arbitration or considered or
used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of
damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply actual damages or award punitive damages, and each party hereby irrevocably waives any claim to
such damages. 
 (c) The Company, the Optionee, each party to the Agreement and any other holder of Stock issued pursuant to
this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This Section 7 applies equally to requests for temporary, preliminary or permanent injunctive relief, except that
in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited purpose of avoiding immediate and irreparable harm. 

(d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States District Court of competent jurisdiction for
the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject
personally to the jurisdiction of the above named courts, that its property is exempt or immune from attachment or execution (except as protected by applicable law), that the suit, action or proceeding is brought in an inconvenient forum, that the
venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court, and (iii) hereby waives and agrees not to seek any review by any court of any other jurisdiction
which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be given. Each Party agrees that its, his or her
submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or proceeding may be enforced in other jurisdictions
by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 
 [SIGNATURE PAGE FOLLOWS] 

  
 5 








 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	BLUEBIRD BIO, INC.
		
	By:	 	 
		 	Name:
		 	Title:
		
		 	 Address:
 840 Memorial
Drive
 Cambridge, MA 02139



 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that the Stock Option granted hereby is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS IN SECTION 7 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 
  

	
	OPTIONEE:
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  


 [SPOUSE’S CONSENT 
 I acknowledge that I have read the 
 foregoing Non-Qualified Stock Option Agreement 

and understand the contents thereof. 

                         
                                         
              ] 







 
	
	DESIGNATED BENEFICIARY:
	
	  
	


  

	
	Beneficiary’s Address:
	
	  
	
	  
	
	  
	









 Appendix A 

STOCK OPTION EXERCISE NOTICE 
 BLUEBIRD BIO, INC. 
 Attention: Office Manager 

840 Memorial Drive 
 Cambridge, MA 02139

 Pursuant to the terms of the stock option agreement between the undersigned and bluebird bio, Inc. (the “Company”)
dated                      (the “Agreement”) under the bluebird bio, Inc. 2010 Stock Option and Grant Plan, I, [Insert Name]
                    , hereby [Circle One] partially/fully exercise such option by including herein payment in the amount of
$                     representing the purchase price for [Fill in number of Underlying Shares]
                     Underlying Shares. I have chosen the following form(s) of payment: 

 

	 	[  ]	1. Cash 

  

	 	[  ]	2. Certified or bank check payable to “bluebird bio, Inc.” 

  

	 	[  ]	3. Other (as referenced in the Agreement and described in the Plan (please describe)) 


                      
                                         
                                         
                                         
                                         
      . 
 In connection with my exercise of the option as set forth above, I hereby represent
and warrant to the Company as follows: 
 (i) I am purchasing the Underlying Shares for my own account for
investment only, and not for resale or with a view to the distribution thereof. 
 (ii) I have had such an
opportunity as I have deemed adequate to obtain from the Company such information as is necessary to permit me to evaluate the merits and risks of my investment in the Company and have consulted with my own advisers with respect to my investment in
the Company. 
 (iii) I have sufficient experience in business, financial and investment matters to be able to
evaluate the risks involved in the purchase of the Underlying Shares and to make an informed investment decision with respect to such purchase. 
 (iv) I can afford a complete loss of the value of the Option Shares and am able to bear the economic risk of holding such Option Shares for an indefinite period of time. 

(v) I understand that the Option Shares may not be registered under the Securities Act of 1933 (it being understood that
the Option Shares are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold or otherwise transferred or disposed of in the absence of
an effective registration statement under the Securities Act 







 
of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing
Option Shares will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Option Shares will include similar restrictive notations. 

 

	
	Sincerely yours,
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  









 EARLY EXERCISE 
 NON-QUALIFIED STOCK OPTION AGREEMENT 
 UNDER THE BLUEBIRD BIO, INC.

 2010 STOCK OPTION AND GRANT PLAN 
  

			
	Name of Optionee:	 	                         (the
“Optionee”)
		
	No. of Option Shares:	 	             Shares of Common Stock
		
	Grant Date:	 	__________
		
	Vesting Commencement Date:	 	                         (the “Vesting
Commencement Date”)
		
	Expiration Date:	 	                         (the “Expiration
Date”)
		
	Option Exercise Price/Share:	 	$                       (the “Option Exercise
Price”)

 Pursuant to the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”), bluebird bio,
Inc., a Delaware corporation (together with any successor thereto, the “Company”), hereby grants to the Optionee, who is an officer, employee, director, Consultant or other key person of the Company or any of its Subsidiaries, an option
(the “Stock Option”) to purchase on or prior to the Expiration Date, or such earlier date as is specified herein, all or any part of the number of shares of Common Stock, par value $0.01 per share (“Common Stock”), of the Company
indicated above (the “Option Shares”), at the Option Exercise Price per share, subject to the terms and conditions set forth in this Early Exercise Non-Qualified Stock Option Agreement (this “Agreement”) and in the Plan. This
Stock Option is not intended to qualify as an “incentive stock option” as defined in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time (the “Code”). 

All capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Plan. 

1. Vesting, Exercisability and Termination. 
 (a) This Stock Option shall be immediately exercisable, regardless of whether the Option Shares are vested. 
 (b) Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting schedule hereunder, the Option Shares shall be vested on the respective
dates indicated below: 
 (i) All Option Shares shall initially be unvested. 

(ii) [25] percent of the Option Shares shall vest on the [first] anniversary of the Vesting Commencement Date; provided
that the Optionee continues to have a Service Relationship with the Company at such time. 

  
 1 








 (iii) Thereafter, the remaining [75] percent of the Option Shares shall vest
in [36] equal monthly installments at the end of each month following the first anniversary of the Vesting Commencement Date, provided the Optionee continues to have a Service Relationship with the Company at such time. 

Notwithstanding anything herein to the contrary, in the case of a Sale Event, this Stock Option and the Option Shares shall be treated as
provided in Section 3(c) of the Plan. 
 (c) Termination. Except as may otherwise be provided by the Committee, if
the Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter terminate subject, in
each case to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If the
Optionee’s Service Relationship terminates by reason of such Optionee’s death or disability (as defined in Section 422(c) of the Code), this Stock Option may continue to be exercised, to the extent the Option Shares are vested on the
date of termination, by the Optionee, the Optionee’s legal representative or legatee for a period of 12 months from the date of death or disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
disability (as defined in Section 422(c) of the Code), and unless otherwise determined by the Committee, this Stock Option may continue to be exercised, to the extent the Option Shares are vested on the date of termination, for a period of 90
days from the date of termination or until the Expiration Date or other termination date, if earlier[; provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately
upon the date of such termination]. 
 For purposes hereof, the Committee’s determination of the reason for termination of
the Optionee’s Service Relationship shall be conclusive and binding on the Optionee and his or her representatives or legatees and any Permitted Transferee. Any portion of this Stock Option with respect to Option Shares that are not vested on
the date of termination of the Service Relationship shall terminate immediately and be null and void. 
 2. Exercise of Stock
Option. 
 (a) The Optionee may exercise this Stock Option only in the following manner: Prior to the Expiration Date, the
Optionee may deliver a Stock Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some or all of the Option Shares. Such notice shall specify the number of
Option Shares to be purchased. To the extent this Stock Option is only partially exercised, such exercise shall first be with respect to the Option Shares, if any, that have previously vested, and then with respect to the Option Shares that will
next vest, with the Option Shares that vest at the latest date being exercised last. Payment of the purchase price may be made by one or more of the methods described in Sections 5(a)(iv)(A), (B), (C), (D) or (E) of the Plan, subject to
the limitations contained in such Sections of the Plan, including the requirement that the Committee specifically approve in advance certain payment methods. 

  
 2 








 (b) In the event the Optionee exercises a portion of this Stock Option with respect to
Option Shares that have not vested, the Optionee shall also deliver a Restricted Stock Agreement covering such unvested Option Shares in the form of Appendix B hereto (the “Restricted Stock Agreement”) with the same vesting schedule
for such Option Shares as set forth for such Option Shares herein. 
 (c) Notwithstanding any other provision hereof or of the
Plan, no portion of this Stock Option shall be exercisable after the Expiration Date. 
 3. Incorporation of Plan.
Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan. 
 4. Transferability of Stock Option. This Agreement is personal to the Optionee and is not transferable by the Optionee in any manner other than by will or by the laws of descent and distribution.
The Stock Option may be exercised during the Optionee’s lifetime only by the Optionee (or by the Optionee’s guardian or personal representative in the event of the Optionee’s incapacity). The Optionee may elect to designate a
beneficiary by providing written notice of the name of such beneficiary to the Company, and may revoke or change such designation at any time by filing written notice of revocation or change with the Company; such beneficiary may exercise the
Optionee’s Stock Option in the event of the Optionee’s death to the extent provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary predeceases the Optionee, the legal representative of the
Optionee may exercise this Stock Option to the extent provided herein in the event of the Optionee’s death. 
 5.
Restrictions on Transfer of Option Shares. The Option Shares acquired upon exercise of the Stock Option shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in
Section 9 of the Plan and, if applicable, the Restricted Stock Agreement. 
 6. Miscellaneous Provisions.

 (a) Equitable Relief. The parties hereto agree and declare that legal remedies may be inadequate to enforce the
provisions of this Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement. 
 (b) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reincorporation, reclassification, stock dividend, stock split, reverse stock split or
other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for a different number or kind of shares of the Company’s stock, the restrictions contained in this Agreement shall
apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of his or her ownership of, Option Shares. 

  
 3 








 (c) Change and Modifications. This Agreement may not be orally changed, modified or
terminated, nor shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Optionee. 

(d) Governing Law. This Agreement shall be governed by and construed in accordance with the General Corporation Law of
the State of Delaware as to matters within the scope hereof, and as to all other matters shall be governed by and construed in accordance with the internal laws of the Commonwealth of Massachusetts, without regard to conflict of law
principles that would result in the application of any law other than the law of the Commonwealth of Massachusetts. 
 (e)
Headings. The headings are intended only for convenience in finding the subject matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 

(f) Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination
shall in no manner affect the legality or enforceability of any other provision hereof. 
 (g) Notices. All notices,
requests, consents and other communications shall be in writing and be deemed given when delivered personally, by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the
Company or the Optionee shall be addressed as set forth underneath their signatures below, or to such other address or addresses as may have been furnished by such party in writing to the other. 

(h) Benefit and Binding Effect. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their
respective successors, permitted assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all the rights of the Company hereunder to the extent of such assignment. 

(i) Counterparts. For the convenience of the parties and to facilitate execution, this Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 
 7.
Dispute Resolution. 
 (a) Except as provided below, any dispute arising out of or relating to the Plan or this Stock
Option, this Agreement, or the breach, termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive
Arbitration Rules and Procedures (the “J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the arbitrators may be entered by any court
having jurisdiction thereof. The place of arbitration shall be Boston, MA. 

  
 4 








 (b) The arbitration shall commence within 60 days of the date on which a written demand for
arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to
three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The
Company, the Optionee, each party to the Agreement and any other holder of Stock issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This
Section 7 applies equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited
purpose of avoiding immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of
any United States District Court of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees not to assert, by way of motion, as a defense, or otherwise, in any such suit,
action or proceeding, any claim that it is not subject personally to the jurisdiction of the above named courts, that its property is exempt or immune from attachment or execution (except as protected by applicable law), that the suit, action or
proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court, and (iii) hereby waives and agrees not to
seek any review by any court of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be
given. Each Party agrees that its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or
proceeding may be enforced in other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 

[SIGNATURE PAGE FOLLOWS] 

  
 5 








 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	BLUEBIRD BIO, INC.
		
	By:	 	 
		 	Name:
		 	Title:
		
		 	Address:
		
		 	 
		
		 	 
		
		 	 


 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that the Stock Option granted hereby is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS IN SECTION 7 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 
  

	
	OPTIONEE:
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  


 [SPOUSE’S CONSENT 
 I acknowledge that I have read the 
 foregoing Non-Qualified Stock Option Agreement 

and understand the contents thereof. 

                         
                                         
                  ] 







 
	
	DESIGNATED BENEFICIARY:
	
	  
	


  

	
	Beneficiary’s Address:
	
	  
	
	  
	
	  
	









 Appendix A 

STOCK OPTION EXERCISE NOTICE 
 BLUEBIRD BIO, INC. 
 Attention:
[                    ] 
  

 
  

 
 Pursuant to the terms
of the stock option agreement between the undersigned and bluebird bio, Inc. (the “Company”) dated                      (the
“Agreement”) under the bluebird bio, Inc. 2010 Stock Option and Grant Plan, I, [Insert Name]                     , hereby [Circle
One] partially/fully exercise such option by including herein payment in the amount of $                     representing the purchase price
for [Fill in number of Option Shares]                      Option Shares. I have chosen the following form(s) of payment: 

 

	 	[  ]	1. Cash 

  

	 	[  ]	2. Certified or bank check payable to “bluebird bio, Inc.” 


 

	 	[  ]	3. Other (as referenced in the Agreement and described in the Plan (please describe)) 


	 	                         
                                         
                                         
                                         
                                         
   .	

 In connection with my exercise
of the option as set forth above, I hereby represent and warrant to the Company as follows: 
 (i) I am
purchasing the Option Shares for my own account for investment only, and not for resale or with a view to the distribution thereof. 
 (ii) I have had such an opportunity as I have deemed adequate to obtain from the Company such information as is necessary to permit me to evaluate the merits and risks of my investment in the Company and
have consulted with my own advisers with respect to my investment in the Company. 
 (iii) I have sufficient
experience in business, financial and investment matters to be able to evaluate the risks involved in the purchase of the Option Shares and to make an informed investment decision with respect to such purchase. 

(iv) I can afford a complete loss of the value of the Option Shares and am able to bear the economic risk of holding such
Option Shares for an indefinite period of time. 
 (v) I understand that the Option Shares may not be registered
under the Securities Act of 1933 (it being understood that the Option Shares are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold
or otherwise transferred or disposed of in the absence of an effective registration statement under the Securities Act 







 
of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing
Option Shares will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Option Shares will include similar restrictive notations. 

(vi) To the extent required, I have executed and delivered to the Company the Restricted Stock Agreement attached as
Appendix B to the Agreement. 
  

	
	Sincerely yours,
	
	  
	Name:
	
	Address:
	
	  
	
	  
	
	  









 Appendix B 

RESTRICTED STOCK AGREEMENT 







 RESTRICTED STOCK AGREEMENT 

UNDER THE BLUEBIRD BIO, INC. 
 2010 STOCK OPTION AND GRANT PLAN 
  

			
	Name of Grantee:	  	                    (the “Grantee”)
		
	No. of Shares:	  	                     Shares of Common Stock (the
“Shares”)
		
	Grant Date:	  	 __________

		
	Vesting Commencement Date:	  	                     (the “Vesting Commencement
Date”)
		
	Per Share Purchase Price:	  	$                     (the “Per Share Purchase
Price”)

 Pursuant to the bluebird bio, Inc. 2010 Stock Option and Grant Plan (the “Plan”), bluebird bio,
Inc., a Delaware corporation (together with any successor entity, the “Company”), hereby grants, sells and issues to the individual named above, who is an officer, employee, director, Consultant or other key person of the Company or any of
the Subsidiaries, the Shares at the Per Share Purchase Price, which represents the fair market value per share on the Grant Date, subject to the terms and conditions set forth herein and in the Plan. The Grantee agrees to the provisions set forth
herein and acknowledges that each such provision is a material condition of the Company’s agreement to issue and sell the Shares to him or her. The Company hereby acknowledges receipt of
$            in full payment for the Shares. All references to share prices and amounts herein shall be equitably adjusted to reflect stock splits, stock dividends,
recapitalizations, mergers, reorganizations and similar changes affecting the capital stock of the Company, and any shares of capital stock of the Company received on or in respect of Shares in connection with any such event (including any shares of
capital stock or any right, option or warrant to receive the same or any security convertible into or exchangeable for any such shares or received upon conversion of any such shares) shall be subject to this Agreement on the same basis and extent at
the relevant time as the Shares in respect of which they were issued, and shall be deemed Shares as if and to the same extent they were issued at the date hereof. 
 All capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Plan. 
 1. Purchase and Sale of Shares; Vesting; Investment Representations. 
 (a)
Purchase and Sale. On the date hereof, the Company hereby sells to the Grantee, and the Grantee hereby purchases from the Company, the number of Shares set forth above for the Per Share Purchase Price. 

  
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 (b) Vesting. On the date of this Agreement, all of the Shares are non-transferable
and subject to a substantial risk of forfeiture and are Shares of Restricted Stock. Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting schedule hereunder, the risk of
forfeiture shall lapse with respect to the Shares on the respective dates indicated below and such Shares shall become vested as follows: 
 (i) All of the Shares shall be vested as of the Vesting Commencement Date. 
 (ii) Notwithstanding anything herein to the contrary in the case of a Sale Event, the Shares of Restricted Stock shall be treated as provided in Section 3(c) of the Plan. 

(c) Investment Representations. In connection with the purchase and sale of the Shares contemplated by Section 1(a) above,
the Grantee hereby represents and warrants to the Company as follows: 
 (i) The Grantee is purchasing the Shares
for the Grantee’s own account for investment only, and not for resale or with a view to the distribution thereof. 
 (ii) The Grantee has had such an opportunity as he or she has deemed adequate to obtain from the Company such information as is necessary to permit him or her to evaluate the merits and risks of the
Grantee’s investment in the Company and has consulted with the Grantee’s own advisers with respect to the Grantee’s investment in the Company. 
 (iii) The Grantee has sufficient experience in business, financial and investment matters to be able to evaluate the risks involved in the purchase of the Shares and to make an informed investment
decision with respect to such purchase. 
 (iv) The Grantee can afford a complete loss of the value of the Shares
and is able to bear the economic risk of holding such Shares for an indefinite period. 
 (v) The Grantee
understands that the Shares are not registered under the Act (it being understood that the Shares are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws
and may not be sold or otherwise transferred or disposed of in the absence of an effective registration statement under the Act and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirements
thereof). The Grantee further acknowledges that certificates representing the Shares will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Shares will include similar restrictive notations. 

2. Repurchase Right. Upon a Termination Event or other Repurchase Event, the Company shall have the right to repurchase the Shares
as set forth in Section 9(c) of the Plan; provided, however, that in the case of a Termination Event, the Company shall only have the right to repurchase Shares of Restricted Stock which are unvested as of the date of such Termination Event.

 3. Restrictions on Transfer of Shares. The Shares (whether or not vested) shall be subject to certain transfer
restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan 

  
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 4. Incorporation of Plan. Notwithstanding anything herein to the contrary, this
Restricted Stock Award shall be subject to and governed by all the terms and conditions of the Plan. 
 5. Miscellaneous
Provisions. 
 (a) Record Owner; Dividends. The Grantee and any Permitted Transferees, during the duration of this
Agreement, shall be considered the record owners of and shall be entitled to vote the Shares if and to the extent the Shares are entitled to voting rights. The Grantee and any Permitted Transferees shall be entitled to receive all dividends and any
other distributions declared on the Shares; provided, however, that the Company is under no duty to declare any such dividends or to make any such distribution. 
 (b) Section 83(b) Election. The Grantee shall consult with the Grantee’s tax advisor to determine whether it would be appropriate for the Grantee to make an election under
Section 83(b) of the Code with respect to this Award. Any such election must be filed with the Internal Revenue Service within 30 days of the date of this Award. If the Grantee makes an election under Section 83(b) of the Code, the Grantee
shall give prompt notice to the Company (and provide a copy of such election to the Company). 
 (c) Equitable Relief.
The parties hereto agree and declare that legal remedies are inadequate to enforce the provisions of this Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this
Agreement. 
 (d) Change and Modifications. This Agreement may not be orally changed, modified or terminated, nor shall
any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Grantee. 
 (e) Governing Law. This Agreement shall be governed by and construed in accordance with the General Corporation Law of the State of Delaware as to matters within the scope thereof, and as to all
other matters shall be governed by and construed in accordance with the internal laws of the Commonwealth of Massachusetts, without regard to conflict of law principles that would result in the application of any law other than the law of the
Commonwealth of Massachusetts. 
 (f) Headings. The headings are intended only for convenience in finding the subject
matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 
 (g) Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination shall in no manner affect the legality or enforceability of any other
provision hereof. 
 (h) Notices. All notices, requests, consents and other communications shall be in writing and be
deemed given when delivered personally, by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to 

  
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the Company or the Grantee shall be addressed as set forth underneath their signatures below, or to such other address or addresses as may have been furnished by such party in writing to the
other. Notices to any holder of the Shares other than the Grantee shall be addressed to the address furnished by such holder to the Company. 
 (i) Benefit and Binding Effect. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their respective successors, assigns, and legal representatives. The
Company has the right to assign this Agreement, and such assignee shall become entitled to all the rights of the Company hereunder to the extent of such assignment. 
 (j) Counterparts. For the convenience of the parties and to facilitate execution, this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of
which shall constitute one and the same document. 
 6. Dispute Resolution. 

(a) Except as provided below, any dispute arising out of or relating to the Plan or the Shares, this Agreement, or the breach,
termination or validity of the Plan, the Shares or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the “J.A.M.S.
Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the arbitrators may be entered by any court having jurisdiction thereof. The place of arbitration
shall be Boston, MA. 
 (b) The arbitration shall commence within 60 days of the date on which a written demand for arbitration
is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to three
depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The
Company, the Grantee, each party to the Agreement and any other holder of Shares or Stock issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This
Section 6 applies equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited
purpose of avoiding immediate and irreparable harm. 

  
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 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States
District Court of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or
proceeding, any claim that it is not subject personally to the jurisdiction of the above named courts, that its property is exempt or immune from attachment or execution (except as protected by applicable law), that the suit, action or proceeding is
brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court, and (iii) hereby waives and agrees not to seek any
review by any court of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be given.
Each Party agrees that its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or proceeding
may be enforced in other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 
 [SIGNATURE PAGE FOLLOWS] 

  
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 IN WITNESS WHEREOF, the Company and the Grantee have executed this Restricted Stock
Agreement as of the date first above written. 
  

			
	BLUEBIRD BIO, INC.
		
	By:	 	  

		 	Name:
		 	Title:


 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof and understands that the Shares granted hereby are subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan and this Agreement, SPECIFICALLY INCLUDING
THE ARBITRATION PROVISIONS IN SECTION 6 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 
  

	
	GRANTEE:
	
	  
	Name:
	
	Address:
	
	
	


  

	
	[SPOUSE’S CONSENT
	 I acknowledge that I have read the
 foregoing Restricted Stock Agreement
 and understand the contents thereof.



                         
                                         
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