Document:

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                               JOHN HANCOCK TOWER
                              200 Clarendon Street
                              Boston, Massachusetts
                                (the "Building")

                          SIXTEENTH AMENDMENT OF LEASE
                          ----------------------------
                                 April 23, 2004

LANDLORD:    100 & 200 Clarendon LLC, a Delaware limited liability company,
             successor in interest to John Hancock Life Insurance Company

TENANT:      Charles River Associates Incorporated, a Massachusetts corporation

EXISTING
PREMISES:    Areas on Floors 31, 32 and 33 of the Building, containing, in the
             aggregate, 63,295 rentable square feet, as shown on Exhibit A-1,
             Exhibit A-2 and Exhibit A-3 attached to the Fifteenth Amendment
             of Lease dated June 7, 2002 consisting of the following:
             Floor 31:           6,000 rentable square feet
             Floor 32:          28,803 rentable square feet
             Floor 33:          28,492 rentable square feet

ORIGINAL
LEASE
DATA         DATE OF LEASE:    March 1, 1978

             TERMINATION
             DATE:                     April 25, 2008

             PREVIOUS
             LEASE
             AMENDMENTS:   First Amendment dated December 16, 1981
                           Second Amendment dated February 24, 1984
                           Third Amendment dated February 28, 1985
                           Fourth Amendment dated February 7, 1986
                           Fifth Amendment dated February 13,1987
                           Sixth Amendment dated August 24,1987
                           Seventh Amendment dated January 31, 1990
                           Eighth Amendment dated December 31, 1991
                           Ninth Amendment dated September 2, 1992

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                           Lease Memorandum dated July 7,1993 (Ninth Amendment)
                           Storage Space Letter dated June 29, 1994
                           Tenth Amendment dated August 24, 1995
                           Eleventh Amendment dated November 25, 1996
                           Twelfth Amendment dated March 19, 1998
                           Thirteenth Amendment dated August 13, 1999
                           Fourteenth Amendment dated April 20, 2000
                           Fifteenth Amendment dated June 7, 2002

             T-26
             EXPANSION
             PREMISES:     An area on the twenty-sixth (26th) floor of the
                           Building, consisting of approximately 19,073
                           rentable square feet, measured using the Modified
                           BOMA Standard, as defined in the Fifteenth Amendment,
                           substantially as shown on Exhibit A, Sixteenth
                           Amendment, a copy of which is attached hereto and
                           incorporated by reference herein

         WHEREAS, Tenant desires to (i) extend the Term of the above-referenced
lease for an additional term; and (ii) lease the T-26 Expansion Premises from
Landlord;

         WHEREAS, Landlord is willing to: (i) extend the Term of the lease; and
(ii) lease the T-26 Expansion Premises to Tenant upon the terms and conditions
hereinafter set forth;

         NOW THEREFORE, the above-described lease, as previously amended (the
"Lease"), is hereinafter further amended as follows:

         1. EXTENSION OF TERM

         The Term of the Lease in respect of the Existing Premises is hereby
extended for an additional term commencing as of April 26, 2008 and terminating
as of the Extended Termination Date, as defined in Paragraph 2 below
("Additional Term"). Said Additional Term shall be upon all of the same terms
and conditions of the Lease in effect immediately preceding the commencement of
such Additional Term (including, without limitation, the Base Year for purposes
of calculating Tenant's rent adjustment for Operating Expenses and the Base Year
for purposes of calculating Tenant's Proportionate Share of Ownership Taxes),
except as follows:

         A. For the period from April 26, 2008 through the Extended Termination
Date, Base Rent in respect of the Existing Premises shall be Two Million
Seventy-Six Thousand Seventy-Six and 00/100 ($2,076,076.00) Dollars per annum
(i.e., a monthly installment of $173,006.33).

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         B. Notwithstanding anything to the contrary contained in this Sixteenth
Amendment, Tenant's Additional Expansion Option, as set forth in Paragraph 10 of
the Fifteenth Amendment of Lease, to lease the Additional Expansion Premises
consisting of 22,090 rentable square feet of space located on the 31st floor of
the Building and outlined on Exhibit A-4 to the Fifteenth Amendment of Lease,
shall remain in full force and effect on the terms set forth in said Paragraph
10 of the Fifteenth Amendment, except that the Option Term Commencement Date has
been revised, per Paragraph 7 of this Sixteenth Amendment, to be the day
immediately following the Extended Termination Date, as defined in Paragraph 2
below.

         C. In the event that any of the provisions of the Lease are
inconsistent with this Amendment or the state of facts contemplated hereby, the
provisions of this Amendment shall control.

         2. DEMISE OF T-26 EXPANSION PREMISES

         Landlord hereby demises and leases to Tenant and Tenant hereby hires
and leases and takes from Landlord the T-26 Expansion Premises for a term
commencing as of the Commencement Date in respect of the T-26 Expansion
Premises, as hereinafter defined, and terminating as of the last day of the
month in which the fifth (5th) anniversary of the Commencement Date in respect
of the T-26 Expansion Premises, as hereinafter defined, occurs ("Extended
Termination Date"). Landlord shall provide Tenant with advance written notice of
the estimated Commencement Date in respect of the T-26 Expansion Premises at
least 1 week prior to such Commencement Date. Promptly after the determination
of the Commencement Date in respect of the T-26 Expansion Premises, Landlord and
Tenant shall confirm such Commencement Date and the Extended Termination Date in
writing. Said demise of the T-26 Expansion Premises shall be upon all of the
same terms and conditions of the Lease, except as follows:

         A. The Commencement Date in respect of the T-26 Expansion Premises
shall be the date ninety (90) days after the date that Landlord substantially
completes the Shell Work, as defined in Paragraph 4 hereof.

         B. Base Rent in respect of the T-26 Expansion Premises shall be Six
Hundred Sixty-Seven Thousand Five Hundred Fifty-Four and 96/100 ($667,554.96)
Dollars per annum (i.e., a monthly installment of $55,629.58), based on $35.00
per rentable square foot of the T-26 Premises per annum, and shall commence on
the Commencement Date in respect of the T-26 Expansion Premises.

         C. The Base Year for purposes of calculating Tenant's rent adjustment
for Operating Expenses in respect of the T-26 Expansion Premises shall be
calendar year 2004.

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         D. The Base Year for purposes of calculating Tenant's Proportionate
Share of Ownership Taxes in respect of the T-26 Expansion Premises shall be
fiscal year 2005 (i.e., July 1, 2004 - June 30, 2005).

         E. Tenant's Proportionate Share of Ownership Taxes in respect of the
T-26 Expansion Premises shall be 1.10%, the percentage resulting from dividing
the number of square feet of rentable area included in the T-26 Expansion
Premises (i.e., 19,073 rentable square feet) by the number of square feet of
rentable area in the Building (i.e., 1,738,779 rentable square feet).

         3. ELECTRICITY IN RESPECT OF T-26 EXPANSION PREMISES

         The consumption of electricity in the T-26 Expansion Premises shall be
measured by a check meter to be installed by Landlord as part of the Shell Work,
as defined in Paragraph 4 below. Tenant shall reimburse Landlord for the entire
cost of such electric current as follows:

         1.       Commencing as of the Commencement Date in respect of the T-26
                  Expansion Premises and continuing until the procedures set
                  forth in Paragraph 2 below are effected, Tenant shall pay to
                  Landlord at the same time and in the same manner that it pays
                  its monthly payments of Base Rent hereunder, estimated monthly
                  payments on account of Tenant's obligation to reimburse
                  Landlord for electricity consumed in the T-26 Expansion
                  Premises.

         2.       Periodically after the Commencement Date in respect of the
                  T-26 Expansion Premises, Landlord shall determine the actual
                  cost of electricity consumed by Tenant in the T-26 Expansion
                  Premises (i.e. by reading Tenant's check meter and by applying
                  the actual electric rate(s) applicable to the preceding
                  period). If the total of Tenant's estimated monthly payments
                  on account of such period is less than the actual cost of
                  electricity consumed in the T-26 Expansion Premises during
                  such period, Tenant shall pay the difference to Landlord when
                  billed therefor. If the total of Tenant's estimated monthly
                  payments on account of such period is greater than the actual
                  cost of electricity consumed in the T-26 Expansion Premises
                  during such period, Tenant may credit the difference against
                  its next installment of rental or other charges due hereunder.

         3.       After each adjustment, as set forth in Paragraph 2 above, the
                  amount of estimated monthly payments on account of Tenant's
                  obligation to reimburse Landlord for electricity in the T-26
                  Expansion Premises shall be adjusted based upon the actual
                  cost of electricity consumed during the immediately preceding
                  period.

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         4.       CONDITION OF T-26 EXPANSION PREMISES

         A. SHELL WORK. Tenant shall take the T-26 Expansion Premises "as-is",
in the condition in which the T-26 Expansion Premises are in as of the
Commencement Date in respect of the T-26 Expansion Premises, without any
obligation on the part of Landlord to prepare or construct the T-26 Expansion
Premises for Tenant's occupancy and without any representation or warranty by
Landlord as to the condition of the T-26 Expansion Premises, except that
Landlord shall, at Landlord's cost, perform the following work ("Shell Work"):

         All existing floor covering and adhesive residue shall be removed to
         concrete slab. Slab shall be level with no penetrations, divots, or
         pockmarks. Slab shall be broom clean, ready for floor covering. All
         hung ceiling components shall be removed. All debris and abandoned
         cables, wires, conduits, ductwork, piping, etc. shall have been removed
         from above the ceiling. A fire protection loop shall be provided. All
         exterior windows shall be provided with existing, functioning building
         standard window treatments. In addition, Landlord shall install
         demising walls, ready for paint, to separate the T-26 Expansion
         Premises from the balance of the 26th floor as shown on Exhibit A,
         Sixteenth Amendment and install a check meter to measure the
         consumption of electricity in the T-26 Expansion Premises.

         B. COMPLETION OF SHELL WORK. Landlord shall use reasonable efforts to
substantially complete the Shell Work on or before the date forty (40) days
after this Sixteenth Amendment is executed by Tenant and Landlord and delivered.
The Shell Work shall be deemed substantially completed on the date that all of
the Shell Work has been performed, other than punch-list work which does not
interfere with Tenant's access or occupancy of the T-26 Premises or the
performance of Tenant's T-26 Work, as defined in Paragraph 5.A below.

         C. EARLY ENTRY. With Landlord's prior written consent, which shall not
be unreasonably withheld, and which consent shall only be required prior to
Tenant's initial request to enter the T-26 Expansion Premises, Tenant shall have
the right to enter the T-26 Expansion Premises after the Shell Work is
substantially completed and prior to the Commencement Date in respect of the
T-26 Expansion Premises, during normal business hours and without payment of
rent, to perform Tenant's T-26 Work, as defined in Paragraph 5(A) below, which
entry shall otherwise be in compliance with the terms of this Lease. Such right
of entry shall be deemed a license from Landlord to Tenant, and any entry
thereunder shall be at the risk of Tenant.

         D. FLOOR 26 LOBBY WORK. In addition to the Shell Work, Landlord shall,
at Landlord's cost, finish the demising walls on the common corridor side of the
T-26 Expansion Premises, repaint and recarpet the common corridor and lobby of
the 26th floor, renovate/upgrade the common area bathrooms on the 26th floor of
the Building to Building standard as currently exists (i.e., as of the date of
this Sixteenth Amendment) in

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the common area bathrooms on the 52nd floor of the Building and construct a
multi-tenant elevator lobby on the 26th floor (collectively, "Floor 26 Lobby
Work"). In addition, to the extent required, Landlord shall be responsible at
Landlord's expense, for bringing the base Building systems, common areas
(including restrooms) and Building core areas serving the 26th floor into
compliance with existing (i.e., as of the date of this Sixteenth Amendment)
federal, state or local environmental laws or other legal requirements and Title
III of the Americans with Disabilities Act of 1990. Landlord shall use
reasonable efforts to complete the Floor 26 Common Area Work on or before the
date one hundred thirty (130) days after this Sixteenth Amendment is executed by
Tenant and Landlord and delivered ("Estimated Lobby Completion Date"). If the
Floor 26 Common Area Work is not completed on or before the date fifty (50) days
after the Estimated Lobby Completion Date ("Outside Lobby Completion Date"), and
such failure is not due to any delay caused by Tenant or Tenant's contractors,
then, as Tenant's sole remedy, Tenant shall be entitled to a credit against
Tenant's obligation to pay Base Rent in respect of the T-26 Expansion Premises
of Two Hundred and 00/100 ($200.00) Dollars per day for each day between the
Outside Lobby Completion Date and the date that the Floor 26 Common Area Work is
completed.

         5. LANDLORD'S CONTRIBUTION IN RESPECT OF T-26 EXPANSION PREMISES

         A. Landlord shall, in the manner hereinafter set forth, contribute up
to Nine Hundred Fifty-Three Thousand Six Hundred Fifty and 00/100 ($953,650.00)
Dollars (i.e., $50.00 per rentable square foot of the T-26 Expansion Premises)
("Landlord's Contribution") towards the cost of all leasehold improvements to be
installed by Tenant in the T-26 Expansion Premises ("Tenant's T-26 Work") and
towards construction and project management fees, tele/data wiring and more
related expenses incurred by Tenant in connection with Tenant's T-26 Work.
Tenant shall not be responsible for any construction management coordination
fees to Landlord in connection with Tenant's T-26 Work. Tenant's T-26 Work shall
be performed in accordance with the Lease including, without limitation,
Paragraph 10 thereof, as amended by Paragraph 8 of the Ninth Amendment of Lease.
In the event that any structural upgrades and/or floor coring for the tele/data
wiring is required in connection with Tenant's T-26 Work, then, subject to
Tenant's compliance with the Lease provisions, as aforesaid, Tenant shall have
the right to reasonable access to the appropriate areas on the 25th floor of the
Building, which work shall be performed in accordance with a mutually agreed
upon procedure scheduled with the Building's management office.

         B. Provided that Tenant is not in default of its obligations under the
Lease at the time that Tenant requests any requisition on account of Landlord's
Contribution, Landlord shall pay the cost of the work shown on each requisition
(as hereinafter defined) submitted by Tenant to Landlord within thirty (30) days
of submission thereof by Tenant to Landlord. For the purposes hereof, a
"requisition" shall mean written documentation showing in reasonable detail the
costs of the improvements then installed by Tenant in the T-26 Expansion
Premises. Each requisition shall be accompanied by evidence reasonably

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satisfactory to Landlord that all work covered by previous requisitions has been
fully paid by Tenant (Landlord hereby agreeing that lien waivers from Tenant's
contractor shall be reasonably satisfactory to Landlord for the purposes
hereof). Landlord shall have the right, upon reasonable advance notice to
Tenant, to inspect Tenant's books and records relating to each requisition in
order to verify the amount thereof. Tenant shall submit requisition(s) no more
often than monthly.

         C. Notwithstanding anything to the contrary herein contained:

         (i) Landlord shall have no obligation to advance funds on account of
Landlord's Contribution unless and until Landlord has received the requisition
in question, together with certifications from Tenant's architect, certifying
that the work shown on the requisition has been performed in accordance with
applicable law and in accordance with Tenant's approved plans.

         (ii) Except with respect to work and/or materials previously paid for
by Tenant, as evidenced by paid invoices provided to Landlord, Landlord shall
have the right to have Landlord's Contribution paid to both Tenant and Tenant's
contractor(s) and vendor(s) jointly, or directly to Tenant's contractor if
Landlord has reason to believe there are or may be outstanding claims by such
contractor(s) or vendor(s).

         (iii) Landlord shall have no obligation to pay Landlord's Contribution
in respect of any requisition submitted after the date which is twelve (12)
months after the Commencement Date in respect of the T-26 Expansion Premises
("Outside Requisition Date").

         (iv) In the event of any unused portion of Landlord's Contribution
remaining after the Outside Requisition Date, Tenant shall be entitled to a
dollar for dollar credit of up to $185,170 of any unused portion of Landlord's
Contribution against Tenant's next obligations to pay Base Rent in respect of
the T-26 Expansion Premises.

         D. Except for Landlord's Contribution and Landlord's Shell Work, Tenant
shall bear all other costs of Tenant's T-26 Work. Landlord shall have no
liability or responsibility for any claim, injury or damage alleged to have been
caused by the particular materials, whether building standard or non-building
standard, selected by Tenant in connection with Tenant's Work.

         6. INTENTIONALLY DELETED

         7. OPTION TO EXTEND LEASE

         A. EXISTING PREMISES: The Option to Extend Lease as set forth in
Paragraph 9 of the Ninth Amendment of Lease, as amended by Paragraph 4 of the
Fifteenth Amendment of Lease, shall continue to be in effect in respect of the
Existing Premises, except that the Option Term Commencement Date shall be the
day immediately
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following the Extended Termination Date, as defined in Paragraph 2 above, and
the Exercise Date shall be not later than twelve (12) months prior to the
Extended Termination Date. All other terms and conditions of said Option to
Extend Lease set forth in said Paragraph 9 of the Ninth Amendment of Lease, as
amended by Paragraph 4 of the Fifteenth Amendment of Lease, shall continue to
apply to the Existing Premises.

         B. T-26 Expansion Premises: The Option to Extend Lease as set forth in
Paragraph 9 of the Ninth Amendment of Lease, as amended by Paragraph 4 of the
Fifteenth Amendment of Lease, as further amended by Paragraph 7(A) above, shall
apply to the T-26 Expansion Premises, except that the Base Rent in respect of
the T-26 Expansion Premises during the Option Term shall be equal to one hundred
percent (100%) of the Fair Rental Value.

         C. Notwithstanding anything to the contrary herein or in the Lease
contained, Tenant shall not have the right to exercise the Option to Extend
Lease in respect of the T-26 Expansion Premises unless Tenant simultaneously
exercises the Option to Extend Lease in respect of the Existing Premises.
However, Tenant shall have the right to exercise the Option to Extend Lease in
respect of the Existing Premises without exercising the Option to Extend Lease
in respect of the T-26 Expansion Premises by so advising Landlord in Tenant's
notice of extension.

         8. TENANT'S RIGHT OF FIRST OFFER WITH RESPECT TO BALANCE OF FLOOR 26

         On the conditions (which conditions Landlord may waive, at its
election, by written notice to Tenant at any time) that Tenant is not in default
of its covenants and obligations under the Lease and that Charles River
Associates Incorporated, itself, or an affiliate, as that term is defined in
Rule 144 promulgated under the Securities Act of 1933, is occupying at least
seventy-five percent (75%) of the premises then demised to Tenant, both at the
time that Landlord is required to give Landlord's Notice, as hereinafter
defined, and as of the Commencement Date in respect of the RFO Premises, and
that Tenant timely and properly exercises the Option to Extend Lease in respect
of the entirety of the premises then demised to Tenant pursuant to Paragraph 9
of the Ninth Amendment to Lease, as amended by Paragraph 4 of the Fifteenth
Amendment of Lease and by Paragraph 7 above, Tenant shall have the following
right to lease the RFO Premises, as hereinafter defined, when the RFO Premises
become available for lease to Tenant, as hereinafter defined.

         A. DEFINITION OF RFO PREMISES

         "RFO Premises" shall be defined as any separately demised area on the
twenty-sixth (26th) floor of the Building, when such area becomes available for
lease to Tenant, as hereinafter defined, during the Term of the Lease. For the
purposes of this Paragraph 8, an RFO Premises shall be deemed to be "available
for lease to Tenant" if, during the term of the Lease, Landlord, in its sole
judgment, determines that such area will become

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available for leasing to Tenant (i.e. when Landlord determines that the then
current tenant of such RFO Premises will terminate its lease and vacate such RFO
Premises, and neither Dechert nor John Hancock Financial Services, Inc.
exercises its right to lease RFO Premises, and when Landlord intends to offer
such area for lease). In no event shall Tenant have any rights under this
Paragraph 8 on or before December 1, 2009 or on or after the date twenty-four
(24) months prior to the expiration of the Term of the Lease (i.e. Landlord
shall have no obligation to give Landlord's Notice, as hereinafter defined, to
Tenant on or before December 1, 2009 or on or after the date twenty-four (24)
months prior to the expiration of the Term of the Lease).

         B. EXERCISE OF RIGHT TO LEASE RFO PREMISES

         Landlord's Notice shall set forth the exact location of the RFO
Premises, the Base Rent applicable to the RFO Premises and the Commencement Date
in respect of the RFO Premises. Tenant shall have the right, exercisable upon
written notice ("Tenant's Exercise Notice") given to Landlord within fifteen
(15) days after the receipt of Landlord's Notice, to lease the RFO Premises. If
Tenant fails timely to give Tenant's Exercise Notice, Tenant shall have no
further right to lease such RFO Premises pursuant to this Paragraph 8, provided
however, that Tenant shall have the right from time to time thereafter
throughout the term of the Lease until Tenant's right to lease the RFO Premises
has lapsed, to give Tenant's Request as to any other subsequently available RFO
Premises. However, if Tenant fails timely to give Tenant's Exercise Notice with
respect to an RFO Premises, and Landlord enters into a lease or other agreement
for such RFO Premises, Tenant shall have a right of first offer on such RFO
Premises when such RFO Premises are thereafter available for lease to Tenant, as
defined above. Upon the timely giving of such notice, Landlord shall lease and
demise to Tenant and Tenant shall hire and take from Landlord, such RFO
Premises, upon all of the same terms and conditions of the Lease except as
hereinafter set forth.

         C. LEASE PROVISIONS APPLYING TO RFO PREMISES

          The leasing to Tenant of such RFO Premises shall be upon
all of the same terms and conditions of the Lease, except as follows:

                  (1) COMMENCEMENT DATE

                  The Commencement Date in respect of such RFO Premises shall
be the date that Landlord delivers such RFO Premises to Tenant.

                  (2) BASE RENT

                  The Base Rent in respect of such RFO Premises shall be the
then Fair Rental Value of the RFO Premises, determined in accordance with the
provisions of Paragraph 9 of the Ninth Amendment, as modified by Paragraph 4(ii)
of the Fifteenth Amendment.

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                  (3) CONDITION OF RFO PREMISES

                  Tenant shall take such RFO Premises "as-is" in its then (i.e.
as of the date of premises delivery) state of construction, finish, and
decoration, without any obligation on the part of Landlord to construct or
prepare any RFO Premises for Tenant's occupancy, except that the determination
of Fair Rental Value shall take into account, without limitation, any tenant
allowances granted by Landlord to Tenant.

         D. EXECUTION OF LEASE AMENDMENTS

                  Notwithstanding the fact that Tenant's exercise of the
above-described option to lease RFO Premises shall be self-executing, as
aforesaid, the parties hereby agree promptly to execute a lease amendment
reflecting the addition of an RFO Premises, except that the Base Rent and Base
Years in respect of such RFO Premises in respect of such RFO Premises may not be
as set forth in such Amendment. At the time that such Base Rent and Base Years
are determined, the parties shall execute a written agreement confirming the
same. The execution of such lease amendment shall not be deemed to waive any of
the conditions to Tenant's exercise of the herein option to lease the RFO
Premises, unless otherwise specifically provided in such lease amendment.

         E. Notwithstanding anything herein to the contrary, Tenant's Right of
First Offer under this Paragraph 8 is subject and subordinate to the existing
rights of Dechert and John Hancock Financial Services, Inc., other tenants in
the Building, to lease the RFO Premises, which rights are summarized in Exhibit
C, Sixteenth Amendment, a copy of which is attached hereto and incorporated by
reference herein.

         9. PARKING

         In addition to the parking permits made available to Tenant pursuant to
Paragraph 12 of the Ninth Amendment of Lease and Paragraph 9 of the Fifteenth
Amendment of Lease, Landlord shall make available to Tenant one (1) parking
permit for the Hancock Garage per 1,500 square feet of rentable square feet of
the T-26 Expansion Premises (or 12 based on 18,517 rentable square feet). Said
use of the additional parking permits shall be upon all of the same terms and
conditions as set forth in Paragraph 12 of the Ninth Amendment of Lease.

         10. BROKER

         Tenant and Landlord each represents and warrants to the other that,
with respect to this Sixteenth Amendment, it has not directly or indirectly
dealt with any broker other than CBRE/Lynch Murphy Walsh Advisors and CB Richard
Ellis/Whittier Partner (the "Brokers") and covenants and agrees to defend, save
harmless and indemnify the other party against any claims for a commission
arising out of any dealings directly or indirectly by such party with any
broker, other than the Brokers, with respect to the execution and

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delivery of this Sixteenth Amendment. Landlord shall apy any commissions to
the Brokers in connection with this Sixteenth Amendment pursuant to a
separate agreement(s) between Landlord and Brokers.

         11. INAPPLICABLE LEASE PROVISIONS AND REVISED LEASE PROVISIONS

         A. Paragraph 6 of the Lease, Page 5A of the Lease, Exhibits 3 and 4 and
Attachment A to the Lease, Paragraph 7 of the Ninth Amendment of Lease,
Paragraph 4 of the Tenth Amendment of Lease (which is incorrectly numbered as
Paragraph 3), Paragraph 4 of the Eleventh Amendment of Lease (which is
incorrectly numbered as Paragraph 3), Paragraph 3 of the Twelfth Amendment of
Lease (which is incorrectly numbered as Paragraph 3), Paragraph 4 of the
Thirteenth Amendment of Lease, Paragraph 4 of the Fourteenth Amendment of Lease,
Paragraph 8 of the Fifteenth Amendment of Lease shall have no applicability to
the T-26 Expansion Premises.

         B. Except as otherwise provided in Sections 20 and 21 of the Lease, and
subject to Tenant's obligations in Section 9 of the Lease, Landlord shall keep
and maintain the roof, exterior walls, structural floor slabs, columns,
elevators, public stairways and corridors, lavatories, equipment (including,
without limitation, sanitary, electrical, heating, air conditioning, or other
systems) and other common facilities of the Building in good condition and
repair.

         C. Notwithstanding anything to the contrary in the Lease contained,
Tenant shall neither assert nor seek to enforce any claim against Landlord, or
Landlord's agents or employees, or the assets of Landlord or of Landlord's
agents or employees, for breach of this Lease or otherwise, other than against
Landlord's interest in the Building of which the premises are a part and in the
uncollected rents, issues and profits thereof, and Tenant agrees to look solely
to such interest for the satisfaction of any liability of Landlord under this
Lease, it being specifically agreed that in no event shall Landlord or
Landlord's agents or employees (or any of the officers, trustees, directors,
partners, beneficiaries, joint venturers, members, stockholders or other
principals or representatives, and the like, disclosed or undisclosed, thereof)
ever be personally liable for any such liability. This paragraph shall not limit
any right that Tenant might otherwise have to obtain injunctive relief against
Landlord or to take any other action which shall not involve the personal
liability of Landlord to respond in monetary damages from Landlord's assets
other than the Landlord's interest in said real estate, as aforesaid. In no
event shall Landlord or Landlord's agents or employees (or any of the officers,
trustees, directors, partners, beneficiaries, joint venturers, members,
stockholders or other principals or representatives and the like, disclosed or
undisclosed, thereof) ever be liable for consequential or incidental damages.
Without limiting the foregoing, in no event shall Landlord or Landlord's agents
or employees (or any of the officers, trustees, directors, partners,
beneficiaries, joint venturers, members, stockholders or other principals or
representatives and the like, disclosed or undisclosed, thereof) ever be liable
for lost profits of Tenant. If by reason of Landlord's failure to acquire title
to the real property of which the premises are a part or to complete
construction of the Building or premises, Landlord shall be

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held to be in breach of this Lease, Tenant's sole and exclusive remedy shall be
a right to terminate this Lease.

         12. NOTICES

         A. For all purposes of the Lease, the notice address for Landlord as
set forth in Paragraph 24 of the Lease is deleted and the following are
substituted in its place:

          100 & 200 Clarendon LLC
          c/o Beacon Capital Partners
          One Federal Street
          Boston, Massachusetts 02110
          Attention:  William A. Bonn, Esq.
          Tel.:  617-457-0400
          Fax:   617-457-0499

          with a copy to:

          Beacon Capital Partners Management LLC
          200 Clarendon Street
          Boston, Massachusetts 02116
          Attention: General Manager
          Tel.:  617-275-0100
          Fax: 617-275-0199

         B. For all purposes of the Lease, the notice addresses for Tenant as
set forth in Paragraph 24 of the Lease are deleted and the following are
substituted in their place:

          Charles River Associates Incorporated
          J. Phillip Cooper, CFO, EVP
          200 Clarendon Street, T-33
          Boston, Massachusetts 02116-5092
          Tel.:  617-425-3000
          Fax:  617-425-3141

          with a copy to:

          Charles River Associates Incorporated
          Annlouise Tirrell, Director Corporate Operations
          200 Clarendon Street, T-33
          Boston, Massachusetts 02116-5092
          Tel.:  617-425-3081
          Fax:  617-425-3141

         13. LANDLORD DEFAULT

                                       12
<Page>

         A. Notwithstanding anything to the contrary in the Lease contained,
Landlord shall not be deemed to be in default of its obligations under the Lease
unless Tenant has given Landlord written notice of such default, and Landlord
has failed to cure said default within thirty (30) days after Landlord receives
such notice or such longer period of time as Landlord may reasonably require to
cure such default.

         B. Except as otherwise expressly provided in the Lease, in no event
shall Tenant have the right to terminate the Lease nor shall Tenant's obligation
to pay Base Rent or other charges under the Lease abate based upon any default
by Landlord of its obligations under the Lease.

         14. BUILDING NAME

         Notwithstanding anything to the contrary in the Lease contained, Tenant
shall (i) refer to and designate the Building solely as John Hancock Tower; (ii)
not to use any Hancock Marks, as hereinafter defined, in a manner, in
conjunction with, or in a recognizable relationship to any persons, entities,
materials or Media, as hereinafter defined, that are Objectionable, as
hereinafter defined; and (iii) not to use the Official Address, as hereinafter
defined, alone as a name or location of the Building (provided that the Official
Address may be used as the second part of the street address following the
identification of the Building as "John Hancock Tower"). Tenant acknowledges and
agrees that any right, benefit or protection available to the Landlord hereunder
with respect to use of the name "John Hancock Tower" shall also be deemed to
accrue to the benefit of, and may be exercised directly by, John Hancock Life
Insurance Company or any of its Affiliates, as hereinafter defined.

         For the purposes of this Paragraph 14, the following terms shall have
the following definitions:

         "Affiliates" means, with respect to any person or entity, any
         corporation, partnership or other business entity which controls or is
         controlled by, or is under common control with such person or entity,
         as applicable. For the purpose of this definition, the word "control"
         (including, with correlative meanings, "controlled by" and "under
         common control with") as used with respect to any corporation,
         partnership or other business entity, shall mean the possession of the
         power to direct or cause the direction of the management and policies
         of such corporation, partnership or other business entity, whether
         through the ownership of voting securities, interests, contract or
         otherwise.

         "Hancock Marks" means, collectively, the Name and Signature, and such
         other logos, service marks, trademarks, domain names (including
         johnhancocktower.com, johnhancocktower.net, and johnhancocktower.org),
         and copyrights, whether registered or

                                       13
<Page>

         unregistered, proprietary to John Hancock Life Insurance Company with
         respect to the Building (including, without limitation, the marks
         registered with the USPTO under Registration Nos. 1287236, 1502565 and
         1494582) or with respect to which Landlord provides Tenant with notice,
         and all Likenesses.

         "Likeness" means a photograph, replica, sketch, drawing, image or any
         other visual or two dimensional or three dimensional representation of
         the Building, which photograph, replica, sketch, drawing, image or
         other representation does not include or display the Name, Plain Name,
         Signature, or any such other logos, service marks, trademarks, and
         copyrights, whether registered or unregistered, proprietary to John
         Hancock Life Insurance Company with respect to the Building.

         "Medium" (or "Media") means any communications or storage medium,
         regardless of method of storage, compilation or memorialization, if
         any, including without limitation, physical storage or representation,
         electronic storage, graphical (including designs and drawings) or
         photographic representation, or writings.

         "Name" means "John Hancock Tower".

         "Objectionable" means any activity or material that: (a) is libelous or
         defamatory, disparaging, pornographic, sexually explicit, unlawful or
         plagiarized; (b) a reasonable person would consider harassing, abusive,
         threatening, harmful, vulgar, profane, obscene, excessively violent,
         racially, ethnically or otherwise objectionable or offensive in any
         way; (c) constitutes a breach of any person's privacy or publicity
         rights, a misrepresentation of facts, hate speech or an infringement of
         any third party's intellectual property rights of any kind, including
         without limitation, copyright, patent, trademark, industrial design,
         trade secret, confidentiality or moral rights; (d) violates or
         encourages others to violate any applicable law; or (e) would have a
         material adverse effect (1) on the reputation or business of Landlord
         or John Hancock Life Insurance Company or (2) on the reputation of the
         Building or (3) on the goodwill associated with the Marks or (f) would
         be materially detrimental to the marketing or leasing of the Building.

         "Official Address" means the official street address assigned to the
         Building by the City of Boston, the United States Postal Service or any
         other governmental authority. As of the date of this First Amendment,
         the Official Address is "200 Clarendon Street."

         "Signature" means the script logo associated with the name "John
         Hancock," as registered with the USPTO under Registration No. 0557033.

                                       14
<Page>

         The Signature, as depicted in the drawing on file with the USPTO,
         consists of a substantial facsimile of the signature of John Hancock
         (1737-1793), patriot of the American Revolution, as said signature
         appears on the Declaration of Independence.

         "USPTO" means the United States Patent and Trademark Office.

         15. HANCOCK COMPETITORS

         Notwithstanding anything to the contrary in the Lease contained, if, at
any time during the term of the Lease, Tenant becomes a Hancock Competitor, as
defined in Exhibit B, Sixteenth Amendment, then Landlord shall have the right to
terminate the Lease upon fifteen (15) days' notice to Tenant.

         16. CONDITION OF LANDLORD'S EXECUTION

         The parties hereby acknowledge that Landlord is only willing to execute
this Sixteenth Amendment in the event that the current tenant (the "Current
Tenant") of the T-26 Expansion Premises agrees to terminate the term of its
lease in respect of the T-26 Expansion Premises. Therefore, Landlord shall have
the right, exercisable upon written notice to Tenant, to render the foregoing
Sixteenth Amendment void and without further force or effect, unless both of the
following events occur on or before April 30, 2004:

         A.       Tenant executes and delivers to Landlord the foregoing
                  Sixteenth Amendment; and

         B.       The Current Tenant executes and delivers to Landlord an
                  agreement, in form and substance acceptable to Landlord,
                  whereby the Current Tenant agrees to terminate the term of its
                  lease in respect of the T-26 Expansion Premises and agrees to
                  an extension of Tenant's right to exercise the Additional
                  Expansion Option, as set forth in Paragraph 10 of the
                  Fifteenth Amendment, to the Exercise Date, as stated in
                  Paragraphs 2 and 7.A of this Sixteenth Amendment ("Current
                  Tenant Agreement").

         In addition, Tenant shall have the right, exercisable upon written
notice to Landlord, to render the foregoing Sixteenth Amendment void and without
further force or effect unless the Current Tenant executes and delivers to
Landlord the Current Tenant Agreement, as defined above, on or before April 30,
2004.

                                       15
<Page>

         17. As hereby amended, the Lease is ratified, confirmed and approved in
all respects.

         EXECUTED under seal as of the date first above-written.

LANDLORD:                                TENANT:
100 & 200 CLARENDON LLC                  CHARLES RIVER ASSOCIATES INCORPORATED

By:  /s/ Phillip T. Branion Jr.          By:   /s/ James C. Burrows
    ---------------------------------          ----------------------
Name:  Phillip T. Branion Jr.            Name: James C. Burrows
      -------------------------------
Title:  V.P.                             Title:  President and
          Hereunto Duly Authorized               Chief Executive Officer
                                         Hereunto Duly Authorized

Date Signed:  4/26/04                    Date Signed:  4/23/04
             ------------------------                 ---------------

                                       16
<Page>

                         EXHIBIT A, SIXTEENTH AMENDMENT

                             T-26 EXPANSION PREMISES

                                       17
<Page>

                         EXHIBIT B, SIXTEENTH AMENDMENT

                               HANCOCK COMPETITORS

         The term "Hancock Competitors," as used in the License to which this
Exhibit is attached, means the organizations listed below and any entity which
is (i) owned or controlled, directly or indirectly, by any of the following
organizations and any successors in interest to the business of any of the
following organizations, and (ii) engaged in the insurance business. An entity
shall be considered to be engaged in the insurance business if its business
includes the writing of insurance policies, the underwriting of insurance
policies, the sale of insurance policies, the placement or acceptance of
insurance risks in primary or other markets, the marketing or distribution of
insurance policies either as a broker, agent or intermediary, consulting
services with respect to insurance, or such other activities which would
generally be recognized to constitute insurance business. As used in the
preceding sentence, the term "insurance policies" shall include all forms of
life, health, property, casualty and annuity products of whatever nature,
whether written on an individual or group basis, as well as structured
settlement agreements, guaranteed investment contracts ("GICs"), synthetic GICs
and funding agreements.

         Metropolitan Life (MetLife)
         Prudential Ins. of America (Prudential Financial)
         Teachers Ins. of Annuity Assoc.
         Northwestern Mutual
         Hartford Life Insurance (Hartford Financial Services)
         Equitable Life Assur. of U.S. (AXA Group)
         Nationwide Life (Nationwide Financial Services)
         New York Life
         Principal Life (Principal Financial Group)
         Lincoln National Life (Lincoln National Corporation)
         Massachusetts Mutual
         Conn. General Life (CIGNA Corporation)
         Travelers Insurance (Citigroup)
         Pacific Life Insurance
         ING Life Ins. & Annuity Co. (ING; also Security Life of Denver)
         IDS Life Minneapolis (American Express Financial)
         Hartford Life & Annuity (Hartford Financial)
         Allstate Life (Allstate Financial)
         Variable Annuity Life (American International Group)
         Jackson National Life (Jackson National Group)
         SunAmerica Life (SunLife Financial)
         American Family Life Assurance (AFLAC)
         State Farm Life (State Farm Group)
         American Skandia Life Assurance-Connecticut
         Great-West Life & Annuity Ins. Co. (Great-West Life Group)
         Aetna Life (Aetna)

                                       18
<Page>

         Guardian Life of America
         Phoenix Life (Phoenix Companies)
         First Colony Life (GE Financial Assurance)
         MONY Life Insurance Co. (MONY Group)
         Jefferson Pilot Life Ins. Co. (Jefferson-Pilot Corporation)
         Provident Life & Accident (Unum Provident)
         Allmerica Financial (AFC)
         Transamerica Life + Annuity (AEGON USA)
         Allianz Life (Allianz)
         Fortis
         Generali
         Prudential PLC

                                       19
<Page>

                         EXHIBIT C, SIXTEENTH AMENDMENT

                         EXISTING RIGHTS OF DECHERT AND
                      JOHN HANCOCK FINANCIAL SERVICES, INC.

1.       Dechert has the option, to be exercised on or after June 1, 2008 and on
         or before December 1, 2009, to add to its premises an area of no less
         than 7,000 contiguous rentable square feet and no more than 10,000
         continguous rentable square feet on either floor 26 or floor 28 of the
         Building as designated by Landlord, to be delivered by Landlord to
         Tenant twelve (12) months after Dechert exercises such option.

2.       John Hancock Financial Services, Inc. ("JHF") has a right of first
         offer to lease any and all space in the Building which the Landlord
         intends to lease to any party. Landlord is to notify JHF of its plans
         to offer space to any party. If JHF declines on space, Landlord has the
         opportunity to market to any third party provided the deal isn't less
         than 95% of the effective rent offered to JHF. If more favorable terms,
         then Landlord must offer to JHF and JHF has 15 days to decide. If
         Landlord doesn't enter into a lease within 12 months after original
         notice to JHF, JHF's rights are reinstated.QuickLinks
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Exhibit 4.4    
    

        CONCENTRA OPERATING CORPORATION

        AND

        THE BANK OF NEW YORK

        as
Trustee 

        SUPPLEMENTAL
INDENTURE 

        Dated
as of May 24, 2004 

        to

        Indenture

        Dated
as of August 17, 1999 

        13%
Series A Senior Subordinated Notes due 2009 

        13%
Series B Senior Subordinated Notes due 2009 

 

        SUPPLEMENTAL INDENTURE dated as of May 24, 2004, by and among Concentra Operating Corporation, a Nevada corporation (the
"Company"), and The Bank of New York, as successor to United States Trust Company of New York, as trustee (the "Trustee"). 

        WHEREAS,
the Trustee, the Company and certain subsidiaries of the Company have heretofore executed and delivered that certain Indenture dated as of August 17, 1999 (as amended,
supplemented or otherwise modified from time to time, the "Indenture"), providing for the issuance of 13% Series A Senior Subordinated Notes due 2009 and 13% Series B Senior Subordinated
Notes due 2009; 

        WHEREAS,
on August 17, 1999, the Company issued $190,000,000 aggregate principal amount of its 13% Series A Senior Subordinated Notes due 2009 and subsequently offered to
exchange them for an equal aggregate principal amount of its 13% Series B Senior Subordinated Notes due 2009 (collectively, the "Notes"); 

        WHEREAS,
on July 24, 2002, the Company redeemed an aggregate principal amount of $47.5 million of the Notes, such that there are now outstanding under the Indenture
$142.5 million aggregate principal
amount of the Notes comprised of $1,651,000 aggregate principal amount of 13% Series A Senior Subordinated Notes due 2009 and $140,849,000 aggregate principal amount of 13% Series B
Senior Subordinated Notes due 2009; 

        WHEREAS,
Section 902 of the Indenture provides that, with the consent of Holders representing a majority in aggregate principal amount of the Notes then outstanding, the Company,
when authorized by a Board Resolution, and the Trustee may enter into an indenture supplemental to the Indenture for the purpose of amending or supplementing the Indenture or modifying the rights of
the Holders (subject to certain exceptions); 

        WHEREAS,
the Company desires and has requested the Trustee to join with it in entering into this Supplemental Indenture for the purpose of amending the Indenture in certain respects as
permitted by Section 902 of the Indenture; 

        WHEREAS,
the Company has been soliciting consents to this Supplemental Indenture upon the terms and subject to the conditions set forth in its Offer to Purchase and Consent Solicitation
Statement dated May 10, 2004 and the related Consent and Letter of Transmittal (which together, including any amendments, modifications or supplements thereto, constitute the "Tender Offer"); 

        WHEREAS,
the execution and delivery of this Supplemental Indenture has been authorized by resolutions of the Board of Directors of the Company; 

        WHEREAS,
the Company (1) has received the consent of the Holders of, and will accept for payment under the Tender Offer promptly after the expiration of the Tender Offer, more
than a majority in principal amount of the outstanding Notes, all as certified by an Officers' Certificate delivered to the Trustee simultaneously with the execution and delivery of this Supplemental
Indenture, (2) has delivered to the Trustee simultaneously with the execution and delivery of this Supplemental Indenture an Opinion of Counsel relating to this Supplemental Indenture as
contemplated by Section 903 of the Indenture and (3) has satisfied all other conditions required under Article 9 of the Indenture to enable the Company and the Trustee to enter
into this Supplemental Indenture. 

        NOW,
THEREFORE, in consideration of the above premises, each party hereby agrees, for the benefit of the others and for the equal and ratable benefit of the holders of the Notes, as
follows: 

 
 

ARTICLE I
  
    DEFINITIONS    
    

        Section 1.1    Deletion of Definitions and Related References.    Section 101 of
Article 1 of the Indenture is hereby amended to delete in their entirety all terms and their respective definitions for 

2

 

which
all references are eliminated in the Indenture as a result of the amendments set forth in Article II of this Supplemental Indenture. 

 
 

ARTICLE II
  
    AMENDMENTS TO INDENTURE    
    

        Section 2.1    Amendments to Articles 5, 7, 8 and 10.    The Indenture is hereby amended by
deleting the following provisions of the Indenture and all references thereto in their entirety: 

Section 501,
Clauses (3), (4), (5), (6), (8) and (9) (Events of Default);

Section 502, first two paragraphs (Acceleration of Maturity; Rescission and Annulment);

Section 515 (Waiver of Usury, Stay or Extension Laws);

Section 704 (Reports by the Company);

Article Eight (Consolidation, Merger, Conveyance, Transfer or Lease);

Section 1002 (Maintenance of Office or Agency);

Section 1004 (Existence);

Section 1005 (Maintenance of Properties);

Section 1006 (Payment of Taxes and Other Claims);

Section 1007 (Maintenance of Insurance);

Section 1008. (Limitation on Incurrence of Indebtedness And Issuance of Preferred Stock);

Section 1009 (Limitation on Restricted Payments);

Section 1010 (Limitations on Dividends and Other Payment Restrictions Affecting Restricted Subsidiaries);

Section 1011 (Limitation on Liens Securing Indebtedness);

Section 1012 (Limitation on Transactions With Affiliates);

Section 1013 (Limitation on Issuances and Sales of Equity Interests in Restricted Subsidiaries);

Section 1014 (Repurchase of Notes at the Option of The Holder Upon a Change of Control);

Section 1015 (Repurchase of Notes at The Option of the Holder Upon an Asset Sale);

Section 1016 (Investment Company);

Section 1017, first paragraph (Limitations on Issuances of Guarantees of Indebtedness);

Section 1018 (Additional Guarantees);

Section 1019 (Limitation on Lines of Business);

Section 1020 (Anti-Layering);

Section 1021 (Sale and Leaseback Transactions);

Section 1024 (Advances of Subsidiaries)

Section 1025 (Payments for Consents); and

Section 1026 (Statement by Officers as to Default; Compliance Certificates). 

 
 

ARTICLE III
  
    MISCELLANEOUS PROVISIONS    
    

        Section 3.1    Defined Terms.    For all purposes of this Supplemental Indenture, except as
otherwise defined or unless the context otherwise requires, terms used in capitalized form in this Supplemental Indenture and defined in the Indenture have the meanings specified in the Indenture. 

        Section 3.2    Indenture.    Except as amended hereby, the Indenture and the Notes are in all
respects ratified and confirmed and all the terms shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all purposes, and every Holder of
Notes heretofore or hereafter authenticated and delivered under the Indenture shall be bound hereby and all terms and conditions of both shall be read together as though they constitute a single
instrument, except that in the case of conflict the provisions of this Supplemental Indenture shall control. 

3

 

        Section 3.3    Governing Law.    THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO PRINCIPLES OF CONFLICT OF LAWS. 

        Section 3.4    Successors.    All agreements of the Company in this Supplemental Indenture and
the Notes shall bind its successors. All agreements of the Trustee in this Supplemental Indenture shall bind its successors. 

        Section 3.5    Duplicate Originals.    All parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them together shall represent the same agreement. It is the express intent of the parties to be bound by the exchange of
signatures on this Supplemental Indenture via telecopy. 

        Section 3.6    Severability.    In case any one or more of the provisions in this Supplemental
Indenture or in the Notes shall be held invalid, illegal or unenforceable, in any respect for any reason, the validity, legality and enforceability of any such provision in every other respect and of
the remaining provisions shall not in any way be affected or impaired thereby, it being intended that all of the provisions hereof shall be enforceable to the full extent permitted by law. 

        Section 3.7    Trustee Disclaimer.    The Trustee accepts the amendment of the Indenture
effected by this Supplemental Indenture and agrees to execute the trust created by the Indenture as hereby amended, but on the terms and conditions set forth in the Indenture, including the terms and
provisions defining and limiting the liabilities and responsibilities of the Trustee, which terms and provisions shall in like manner define and limit its liabilities and responsibilities in the
performance of the trust created by the Indenture as hereby amended, and without limiting the generality of the foregoing, the Trustee shall not be responsible in any manner whatsoever for or with
respect to any of the recitals or statements contained herein, all of which recitals or statements are made solely by the Company, and the Trustee makes no representation with respect to any such
matters. Additionally, the Trustee makes no representations as to the validity or sufficiency of this Supplemental Indenture. 

        Section 3.8    Effectiveness.    The provisions of this Supplemental Indenture shall be
effective only upon execution and delivery of this instrument by the parties hereto. Notwithstanding the foregoing sentence, the provisions of this Supplemental Indenture shall become operative only
upon the purchase of more than a majority in principal amount of the outstanding Notes pursuant to the Tender Offer. The Company shall notify the Trustee promptly after the occurrence of such
purchase. 

        Section 3.9    Endorsement and Change of Form of Notes.    Any Notes authenticated and
delivered after the close of business on the date that this Supplemental Indenture becomes operative in substitution for Notes then outstanding and all Notes presented or delivered to the Trustee on
and after that date for such purpose shall be stamped, imprinted or otherwise legended by the Trustee, with a notation as follows: 

"Effective
as of            , 2004, certain restrictive covenants of the Company and certain Events of Default have been eliminated or limited, as provided in the Supplemental Indenture, dated as
of            , 2004. Reference is
hereby made to said Supplemental Indenture, copies of which are on file with the Trustee, for a description of the amendments made therein." 

        Section 3.10    Effect of Headings.    The Section headings herein are for convenience only
and shall not affect the construction thereof. 

        [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

4

        IN
WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed as of the day and year written above. 

	Attest:	 	CONCENTRA OPERATING CORPORATION,

as Obligor
	

/s/  RICHARD A. PARR II      
	
 	

By:	

/s/  DOUGLAS C. RICE      

	Richard A. Parr II, Secretary	 	Name:	Douglas C. Rice
	 	 	Title:	Senior Vice President & Controller
	

 	
 	

 	

 
	

 	
 	
THE BANK OF NEW YORK,

as Trustee
	

 	
 	

By:	

/s/  JEREMY FINKELSTEIN      

	 	 	Name:	Jeremy Finkelstein
	 	 	Title:	Assistant Treasurer

QuickLinks

Exhibit 4.4

ARTICLE I DEFINITIONS

ARTICLE II AMENDMENTS TO INDENTURE

ARTICLE III MISCELLANEOUS PROVISIONS

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