Document:

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                                                                   EXHIBIT 10.39

                              AMENDMENT OF LEASE
                              ------------------

     THIS AGREEMENT, made as of the 16 day of July, 1999, by and between EAST
STREET ASSOCIATES, a Massachusetts limited partnership (hereinafter referred to
as "Landlord") and ZEFER CORP., a Delaware corporation (hereinafter referred to
as "Tenant")

                        W I T N E S S E T H    T H A T:

     WHEREAS, pursuant to an existing lease agreement between the parties dated
June 17, 1999 (hereinafter referred to as the "Lease"), Landlord has leased to
Tenant certain Premises contained in the Building known and numbered as 711
Atlantic Avenue, Boston, Massachusetts, all as more particularly described and
set forth in the Lease; and

     WHEREAS, Landlord and Tenant wish to provide for the expansion of the
Premises, subject to the provisions hereof;

     NOW THEREFORE, in consideration of the foregoing recitals and for further
good and valuable consideration, the receipt and adequacy whereof are hereby
acknowledged, Landlord and Tenant do hereby agree as follows:

     1.   That portion of the fourth (4th) floor of the Building shown on the
plan attached hereto as Exhibit A and made a part hereof and agreed to contain
4,500 square feet of rentable area (hereinafter referred to as the "Expansion
Area") shall be added to the Premises subject to all terms, covenants,
conditions and provisions of the Lease except as otherwise set forth herein.

     2.   The Commencement Date applicable to the Expansion Area shall be the
date (hereinafter referred to as the "Delivery Date") on which Landlord delivers
possession of said Area to Tenant broom clean and free and clear of other
tenants and occupants, any furniture or other personal property having been
removed. The Term of the Lease with respect to the Expansion Area shall end at
the same time as the Term of the Lease applicable to the remainder of the
Premises.
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     3.   Subject to Landlord's repair obligations under the Lease, Tenant shall
accept the Expansion Area "as is", in its existing condition as of the Delivery
Date, and all work necessary to prepare the Expansion Area for occupancy shall
be performed by Tenant in accordance with Section 8 and the other applicable
provisions of the Lease.

     4.   Tenant shall pay to Landlord Basic Rent with respect to the Expansion
Area at the rate of $144,000 per annum, payable in equal monthly installments of
$12,000 each as generally set forth in the Lease. Notwithstanding the foregoing,
no such installments shall be due with respect to the ninety (90) day period
beginning on the Commencement Date applicable to the Expansion Area.

     5.   The percentage applicable to the calculation of the Operating Cost
Excess and the Tax Excess shall be 5.65% in the case of the Expansion Area.

     6.   At Landlord's option, electrical energy may be supplied to the
Expansion Area in common with other rentable area in the Building, in which
case, in lieu of purchasing such electrical energy directly from the public
utility company servicing the Building, Tenant shall pay to Landlord, from time
to time upon billing, a proportionate share of all charges for such electrical
energy computed on the basis of the ratio between the rentable area of the
Expansion Area and the rentable area (consistently measured) of the portion of
the Building serviced by the same electrical meter which services the Expansion
Area (hereinafter referred to as the "Service Area"). Such payment shall be
prorated to exclude any period not included within the Term of the Lease
applicable to the Expansion Area and shall be equitably adjusted if any portion
of the Service Area other than the Expansion Area is not occupied at any time
during the relevant billing period. Any electrical energy charges of which
Tenant is obligated to pay a share pursuant to the foregoing provisions shall
not be included as part of Operating Costs.

                                      -2-
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     7.   Unless the context requires otherwise, the terms used herein shall be
construed in conformity with the definitions set forth in the Lease.

     8.   Except as herein modified, the Lease is hereby ratified and confirmed.

     IN WITNESS WHEREOF, Landlord and Tenant have caused this instrument to be
executed under seal as of the day and year first above written.

                                    EAST STREET ASSOCIATES

                                    By [ILLEGIBLE]^^
                                       ------------------------------
                                    Its General Partner
                                        -----------------------------
                                           title (duly-authorized)

                                    ZEFER CORP.

                                    By [ILLEGIBLE]^^
                                       ------------------------------
                                    Its Vice President, Finance
                                        -----------------------------
                                           title (duly-authorized)

                                      -3-
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                                   EXHIBIT A
                                   ---------

                           [FLOOR PLAN APPEARS HERE]

                                      -4-<PAGE>

                                                                   EXHIBIT 10.40

                              AMENDMENT OF LEASE
                              ------------------

     THIS AGREEMENT, made as of the ____ day of September, 1999, by and between
EAST STREET ASSOCIATES, a Massachusetts limited partnership (hereinafter
referred to as "Landlord") and ZEFER CORP., a Delaware corporation (hereinafter
referred to as "Tenant")

                        W I T N E S S E T H    T H A T:

     WHEREAS, pursuant to an existing lease agreement between the parties dated
June 17, 1999, as from time to time amended (hereinafter referred to as the
"Lease"), Landlord has leased to Tenant certain Premises contained in the
Building known and numbered as 711 Atlantic Avenue, Boston, Massachusetts, all
as more particularly described and set forth in the Lease; and

     WHEREAS, Landlord and Tenant wish to provide for the expansion of the
Premises, subject to the provisions hereof;

     NOW THEREFORE, in consideration of the foregoing recitals and for further
good and valuable consideration, the receipt and adequacy whereof are hereby
acknowledged, Landlord and Tenant do hereby agree as follows:

     1. That portion of the fourth (4th) floor of the Building shown on the plan
attached hereto as Exhibit A and made a part hereof and agreed to contain 575
square feet of rentable area (hereinafter referred to as the "Expansion Area")
shall be added to the Premises subject to all terms, covenants, conditions and
provisions of the Lease except as otherwise set forth herein.

     2. The Commencement Date applicable to the Expansion Area shall be the date
(hereinafter referred to as the "Delivery Date") on which Landlord delivers
possession of said Area to Tenant broom clean and free and clear of other
tenants and occupants, any furniture or other personal property having been
removed. The Term of the Lease with respect to the Expansion Area shall end at
the same time as the Term of the Lease applicable to the remainder of the
Premises.
<PAGE>

     3. Subject to Landlord's repair obligations under the Lease, Tenant shall
accept the Expansion Area "as is", in its existing condition as of the Delivery
Date, and all work necessary to prepare the Expansion Area for occupancy
(including without limitation the reconfiguration of demising walls wherever
necessary to separate the Premises from adjoining areas of the Building) shall
be performed by Tenant in accordance with Section 8 and the other applicable
provisions of the Lease.

     4. Tenant shall pay to Landlord Basic Rent with respect to the Expansion
Area at the rate of $18,400.08 per annum, payable in equal monthly installments
of $1,533.34 each as generally set forth in the Lease. Notwithstanding the
foregoing, no such installments shall be due with respect to the period prior to
the date on which Basic Rent first becomes payable with respect to the adjoining
portion of the Premises on the fourth (4th) floor of the Building.

     5. The percentage applicable to the calculation of the Operating Cost
Excess and the Tax Excess shall be 0.722% in the case of the Expansion Area.

     6. At Landlord's option, electrical energy may be supplied to the Expansion
Area in common with other rentable area in the Building, in which case, in lieu
of purchasing such electrical energy directly from the public utility company
servicing the Building, Tenant shall pay to Landlord, from time to time upon
billing, a proportionate share of all charges for such electrical energy
computed on the basis of the ratio between the rentable area of the Expansion
Area and the rentable area (consistently measured) of the portion of the
Building serviced by the same electrical meter which services the Expansion Area
(hereinafter referred to as the "Service Area"). Such payment shall be prorated
to exclude any period not included within the Term of the Lease applicable to
the Expansion Area and shall be equitably adjusted if any portion of the Service
Area other than the Expansion Area is not occupied at any time during the
relevant

                                      -2-
<PAGE>

billing period. Any electrical energy charges of which Tenant is obligated to
pay a share pursuant to the foregoing provisions shall not be included as part
of Operating Costs.

     7.   Unless the context requires otherwise, the terms used herein shall be
construed in conformity with the definitions set forth in the Lease.

     8.   Except as herein modified, the Lease is hereby ratified and confirmed.
IN WITNESS WHEREOF, Landlord and Tenant have caused this instrument to be
executed under seal as of the day and year first above written.

                                    EAST STREET ASSOCIATES

                                    By _________________________

                                    Its _________________________
                                         title (duly-authorized)

                                    ZEFER CORP.

                                    By _________________________

                                    Its _________________________
                                         title (duly-authorized)

                                      -3-
<PAGE>

                                   EXHIBIT A
                                   ---------

                           [PLAN OF EXPANSION AREA]
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                                                                       EXHIBIT A

                        [FLOOR PLAN OF EXPANSION AREA]
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                   [LETTERHEAD OF ROPES & GRAY APPEARS HERE]

                                                            July 30, 1999

                                  MEMORANDUM

     TO:  Sean Mullaney                      COPY TO:  Rick Lowe (w/enc.)

   FROM:  Jason Dunn

SUBJECT:  Lease for Space in 711 Atlantic Avenue

________________________________________________________________________________

     Enclosed is one (1) fully-executed, original copy of the Lease between East
Street Associates and Zefer for the 6th floor of 711 Atlantic Avenue, together
with the Amendment of Lease for certain additional space on the 4th floor of
the building. Also enclosed is a photocopy of the landlord counterpart to the
side letter agreement regarding the security deposit.

     Please let me know if you have any questions regarding the enclosed.

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