Exhibit 10.8


MOMENTA PHARMACEUTICALS, INC.


Restricted Stock Agreement

Granted Under 2004 Stock Incentive Plan, as amended


AGREEMENT made on August 22, 2006 between Momenta
Pharmaceuticals, Inc., a Delaware corporation
(the “Company”), and Craig Wheeler (the “Participant”).


For valuable consideration, receipt of which is
acknowledged, the parties hereto agree as follows:


1.             Issuance of Shares.


The Company hereby issues to the Participant, subject
to the terms and conditions set forth in this Agreement and in the Company’s
2004 Stock Incentive Plan, as amended (the “Plan”), 100,000 shares (the “Shares”)
of common stock, $0.0001 par value per share, of the Company (“Common Stock”).  The Shares will be held in book entry by the
Company’s transfer agent in the name of the Participant for that number of
Shares issued to the Participant.  The
Participant agrees that the Shares shall be subject to the forfeiture
provisions set forth in Section 2 of this Agreement and the restrictions
on transfer set forth in Section 3 of this Agreement.


2.             Vesting.


(a)           Subject
to the acceleration provisions set forth in that certain Employment Agreement,
dated August 22, 2006, between the Company and the Participant (the “Employment
Agreement”), in the event that the Participant ceases to be employed by the
Company prior to August 21, 2010, for any reason or no reason, with or without
cause, all of the Unvested Shares (as defined below) will be immediately and
automatically forfeited and returned to the Company for no consideration effective
as of the date of termination of employment. 
The Participant will have no further rights with respect to any Shares
that are so forfeited.  “Unvested
Shares” means the total number of Shares multiplied by the Applicable
Percentage.  The “Applicable
Percentage” shall be (i) 100% during the 48-month period ending on
August 21, 2010, and (ii) zero after August 21, 2010.


(b)           For purposes of this
Agreement, employment with the Company shall include employment with a parent
or subsidiary of the Company, or any successor to the Company, subject to the
terms and provisions of the Employment Agreement.


3.             Restrictions on Transfer.


(a)           The Participant shall not sell,
assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of
law or otherwise (collectively “transfer”) any Shares, or any interest
therein, until such Shares have vested, except that the Participant may
transfer such Shares (i) to or for the benefit of any spouse, children,
parents, uncles, aunts, siblings, grandchildren and any other relatives
approved by the Board of Directors (collectively, “Approved Relatives”)
or to a trust established solely for the benefit of the Participant and/or









 



Approved Relatives, provided that such Shares shall remain
subject to this Agreement (including without limitation the restrictions on
transfer set forth in this Section 3 and the forfeiture provisions contained in
Section 2) and such permitted transferee shall, as a condition to such
transfer, deliver to the Company a written instrument confirming that such
transferee shall be bound by all of the terms and conditions of this Agreement
or (ii) as part of the sale of all or substantially all of the shares of
capital stock of the Company (including pursuant to a merger or consolidation),
provided that, in accordance with the Plan and except as otherwise
provided herein, the securities or other property received by the Participant
in connection with such transaction shall remain subject to this Agreement.


(b)           The Company shall
not be required (i) to transfer on its books any of the Shares which have been
transferred in violation of any of the provisions set forth in this Agreement
or (ii) to treat as owner of such Shares or to pay dividends to any transferee
to whom such Shares have been transferred in violation of any of the provisions
of this Agreement.


4.             Restrictive Legends.


All Shares subject to this Agreement subject to the
following restriction, in addition to any other legends that may be required
under federal or state securities laws:


“The shares of stock
represented by this certificate are subject to forfeiture provisions and
restrictions on transfer set forth in a certain Restricted Stock Agreement
between the corporation and the registered owner of these shares (or his
predecessor in interest), and such Agreement is available for inspection
without charge at the office of the Secretary of the corporation.”


5.             Provisions of the Plan.


This Agreement is subject to the provisions of the
Plan, a copy of which is furnished to the Participant with this Agreement.  Capitalized terms used, but not otherwise
defined, herein shall have the meaning given to them in the Plan.


6.             Withholding Taxes; Section 83(b) Election.


(a)           The Participant
acknowledges and agrees that the Company has the right to deduct from payments
of any kind otherwise due to the Participant any federal, state, local or other
taxes of any kind required by law to be withheld with respect to the issuance
of the Shares to the Participant or the lapse of the forfeiture provisions.  For so long as the Common Stock is registered
under the Exchange Act, the Participant may satisfy such tax obligations
in whole or in part by delivery of shares of Common Stock, including shares
retained from this award, valued at their Fair Market Value; provided, however,
that (i) the total tax withholding where stock is being used to satisfy such
tax obligations cannot exceed the Company’s minimum statutory withholding
obligations (based on minimum statutory withholding rates for federal and state
tax purposes, including payroll taxes, that are applicable to such supplemental
taxable income) and (ii) satisfaction of such tax obligations through shares of
the Company’s Common Stock, including Shares retained from this award, may only
be authorized by the Company’s



 2
 






 



Compensation
Committee in its sole discretion at any time prior to the occurrence of a
vesting date (whereby such Committee may adopt a resolution permitting the
Participant to satisfy his tax withholding obligation through the surrender of
shares of the Company’s Common Stock, including a portion of the Shares the
vesting of which gives rise to the withholding obligations).  Shares surrendered to satisfy tax withholding
requirements cannot be subject to any repurchase, forfeiture, unfulfilled
vesting or other similar requirements.


(b)           The Participant has
reviewed with the Participant’s own tax advisors the federal, state, local and
other tax consequences of this investment and the transactions contemplated by
this Agreement.  The Participant is
relying solely on such advisors and not on any statements or representations of
the Company or any of its agents.  The
Participant understands that the Participant (and not the Company) shall be
responsible for the Participant’s own tax liability that may arise as a result
of this investment and the transactions contemplated by this Agreement.


THE PARTICIPANT AGREES
NOT TO FILE AN ELECTION UNDER SECTION 83(B) OF THE INTERNAL REVENUE CODE WITH
RESPECT TO THE ISSUANCE OF THE SHARES.


7.             Miscellaneous.


(a)           No Rights to Employment.  Subject to the acceleration provisions set
forth in the Employment Agreement, the Participant acknowledges and agrees that
the vesting of the Shares pursuant to Section 2 hereof is earned only by
continuing service as an employee of the Company (not through the act of being
hired or being granted the Shares hereunder). 
The Participant further acknowledges and agrees that the transactions
contemplated hereunder and the vesting schedule set forth herein do not
constitute an express or implied promise of continued engagement as an employee
for the vesting period, for any period, or at all.


(b)           Severability.  The invalidity or unenforceability of any
provision of this Agreement shall not affect the validity or enforceability of
any other provision of this Agreement, and each other provision of this
Agreement shall be severable and enforceable to the extent permitted by law.


(c)           Waiver.  Any provision for the benefit of the Company
contained in this Agreement may be waived, either generally or in any
particular instance, by the Board of Directors of the Company.


(d)           Binding Effect.  This Agreement shall be binding upon and
inure to the benefit of the Company and the Participant and their respective
heirs, executors, administrators, legal representatives, successors and
assigns, subject to the restrictions on transfer set forth in Section 3 of this
Agreement.


(e)           Notice.   Each notice relating to this Agreement shall
be in writing and delivered in person or by first class mail, postage prepaid,
to the address as hereinafter provided. 
Each notice shall be deemed to have been given on the date it is
received.  Each notice to the Company
shall be addressed to it at its offices at 675 West Kendall Street, Cambridge,



 3
 






 



Massachusetts
02142 (Attention:  Vice President, Legal
Affairs).  Each notice to the Participant
shall be addressed to the Participant at the Participant’s last known address.


(f)            Pronouns.  Whenever the context may require, any
pronouns used in this Agreement shall include the corresponding masculine,
feminine or neuter forms, and the singular form of nouns and pronouns shall
include the plural, and vice versa.


(g)           Entire Agreement.  This Agreement, the Employment Agreement and
the Plan constitute the entire agreement between the parties, and supersede all
prior agreements and understandings, relating to the subject matter of this
Agreement.


(h)           Amendment.  This Agreement may be amended or modified
only by a written instrument executed by both the Company and the Participant.


(i)            Governing Law.  This Agreement shall be construed,
interpreted and enforced in accordance with the internal laws of the State of
Delaware without regard to any applicable conflicts of laws.


(j)            Interpretation.  The interpretation and construction of any
terms or conditions of the Plan, or of this Agreement or other matters related
to the Plan by the Compensation Committee of the Board of Directors of the
Company shall be final and conclusive.


(k)           Participant’s
Acknowledgments.  The Participant
acknowledges that he: (i) has read this Agreement; (ii) has been represented in
the preparation, negotiation, and execution of this Agreement by legal counsel
of the Participant’s own choice or has voluntarily declined to seek such
counsel; (iii) understands the terms and consequences of this Agreement; (iv)
is fully aware of the legal and binding effect of this Agreement; and (v)
understands that the law firm of Wilmer Cutler Pickering Hale and Dorr LLP is
acting as counsel to the Company in connection with the transactions contemplated
by the Agreement, and is not acting as counsel for the Participant.


(l)            Delivery of
Certificates.  The Participant may
request that the Company deliver the Shares in certificated form with respect
to any Shares that have ceased to be subject to forfeiture pursuant to Section
2.


(m)          No Deferral.  Notwithstanding anything herein to the
contrary, neither the Company nor the Participant may defer the delivery of the
Shares.



 4
 






 



 


IN WITNESS WHEREOF, the parties hereto have executed
this Agreement as of the day and year first above written.


	
  

  	
  MOMENTA PHARMACEUTICALS, INC.

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
  By:

  	
    /s/ Richard P. Shea

  
	
   

  	
   

  	
  Richard P. Shea

  
	
   

  	
   

  	
  Vice President, Chief Financial Officer

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
      /s/
  Craig A. Wheeler

  
	
   

  	
  Craig Wheeler

  



 



 5