Document:

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                                                                  Exhibit 10(ii)

                          ELEVENTH AMENDMENT TO LEASE
                          ---------------------------

     This Eleventh Amendment to Lease (this "Amendment") is made as of August 1,
2000 by and between LaSalle Bank, N.A., as successor trustee to American
National Bank and Trust Company of Chicago, as Trustee under Trust Agreement
dated April 5, 1990 and known as Trust No. 110513-07 ("Landlord"), and The
Northern Trust Company, an Illinois banking corporation.

                                    Recitals
                                    --------

     A.  American National Bank and Trust Company of Chicago, as Trustee under
Trust No. 65287 ("Prior Landlord") and Tenant entered into that certain Lease
dated August 27, 1985 (the "Original Lease") as amended by that certain First
Amendment to Agreement of Lease dated August 15, 1986 (the "First Amendment"),
that certain Second Amendment to Agreement of Lease dated August 6, 1987 (the
"Second Amendment"), and that certain Third Amendment to Agreement of Lease
dated May 20, 1988 (the "Third Amendment").

     B.  The Original Lease, as amended by the First Amendment, Second Amendment
and Third Amendment, was assigned by Prior Landlord to Landlord by an assignment
dated April 6, 1990.

     C.  Landlord and Tenant further amended the Original Lease by that certain
Fourth Amendment to Agreement of Lease dated May 1, 1990, that certain Fifth
Amendment to Agreement of Lease dated January 12, 1995, that certain Sixth
Amendment to Agreement of Lease dated November 30, 1995 and, certain Seventh
Amendment dated February 24, 1998, that certain Eighth Amendment to Lease dated
January 31, 2000, that certain Ninth Amendment to Lease dated January 31, 2000
(the "Ninth Amendment") and that certain Tenth Amendment to Lease dated February
1, 2000.  The Original Lease, as amended by all of the aforedescribed
amendments, is hereinafter referred to as the "Lease."  All capitalized terms
used in this Amendment and not otherwise defined shall have the meanings
ascribed to them in the Lease.

     D.  Pursuant to the Ninth Amendment, Tenant leases from Landlord
approximately 20,866 rentable square feet on the 36/th/ floor of the building
located at 181 West Madison Street, Chicago, Illinois (the "36/th/ Floor
Space"), for a term (the "36/th/ Floor Space Term") ending on December 31, 2000.

     E.  Landlord and Tenant have agreed to extend the 36/th/ Floor Space Term
and wish to confirm their agreements regarding such extension in this Amendment.

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
contained herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant agree as
follows:

     1.  36/th/ Floor Space Term Extension.  The 36/th/ Floor Space Term is
         ---------------------------------
hereby extended to at least January 31, 2001 and, thereafter, on a month-to-
month basis, subject to the
<PAGE>

parties' rights hereinafter described. Commencing February 1, 2001, either party
shall have the right to terminate the Lease, as to the 36/th/ Floor Space only,
effective as of the last day of a given month, by written notice given to the
other party no later than the first (1/st/) day of said month. If such notice is
not given by the first (1/st/) day of a month, then the 36/th/ Floor Space Term
shall be extended at least until the last day of such month on the same terms as
are set forth in the Ninth Amendment. If such notice is given, the Lease shall
terminate, as to the 36/th/ Floor Space, as of the last day of the relevant
month, Tenant shall surrender the 36/th/ Floor Space in accordance with the
terms of the Lease regarding surrender of space, and neither party shall have
any further liability with respect to the 36/th/ Floor Space, except for
liabilities arising prior to such termination date.

     2.  Brokers.  Tenant represents that, except for Douglas Elliman-Beitler
         -------
and Staubach Midwest, LLC, it has not dealt with any real estate brokers in
connection with this Eleventh Amendment.  Notwithstanding the foregoing, no
party is entitled to a commission or fee with respect to the extension of the
36/th/ Floor Space Term or the negotiation of this Eleventh Amendment.  Tenant
hereby agrees to indemnify, defend, and hold Landlord harmless from and against
any and all claims of Staubach Midwest, LLC, or any other party claiming to have
represented Tenant, for broker commission or fees in connection with this
Eleventh Amendment.

     Landlord represents that, except for Douglas Elliman-Beitler and Staubach
Midwest, LLC, it has not deal with any real estate brokers in connection with
this Eleventh Amendment.  Notwithstanding the foregoing, no party is entitled to
a commission or fee with respect to the extension of the 36/th/ Floor Space Term
or the negotiation of this Eleventh Amendment.  Landlord hereby agrees to
indemnify, defend, and hold Tenant harmless from and against any and all claims
of Douglas Elliman-Beitler, or any other party claiming to have represented
Landlord, for broker commissions or fees in connection with this Eleventh
Amendment.

     3.  Merger.  All negotiations, considerations, representations and
         ------
understandings between Landlord and Tenant relating to this Eleventh Amendment
are incorporated herein and may be modified or altered only by agreement, in
writing, between Landlord and Tenant.  No modification, termination, or
surrender of the Lease, as modified by this Eleventh Amendment, or surrender of
the Premises (including the 36/th/ Floor Space) or any part thereof or of any
interest therein by Tenant shall be valid or effective unless agreed to and
accepted, in writing, by Landlord an no act by any representative or agent of
Landlord other than delivery of such a written agreement and acceptance by
Landlord shall constitute agreement to and acceptance thereof.  Any prior
negotiations or intentions of the parties relating to this Ninth Amendment,
whether oral or evidenced by written documentation dated prior to the date of
this Ninth Amendment, are null and void, unless specifically incorporated herein
by reference.

     4.  Exoneration Clause.  This Eleventh Amendment is executed by the
         ------------------
undersigned, LaSalle Bank, N.A., as successor trustee to American National Bank
and Trust Company of Chicago, not personally, but as Trustee in the exercise of
the power and authority conferred upon and vested in it as such Trustee and
under the express direction of the beneficiaries of the said Trust.  It is
expressly understood and agreed that all of the warranties, indemnities,
representations, covenants, undertaking sand agreements herein made on the part
of the Trustee are undertaken by it solely in its capacity as Trustee and not
personally.  No personal liability or
<PAGE>

personal responsibility is assumed by or shall at any time be asserted or
enforceable against the Trustee on account of any warranty, indemnity,
representation, covenant, undertaking or agreement of the Trustee in this
instrument.

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

LANDLORD:                      LASALLE BANK, N.A., as Successor Trustee to
                               American National Bank and Trust Company of
                               Chicago, not individually, but solely as Trustee
                               under Trust Agreement dated April 5, 1990 and
                               known as Trust No. 110513-07

                               By:   /s/ David Rosenfeld
                                  ------------------------------------------
                               Title:  Assistant Vice President

                               Attest:  Attestation not required by LaSalle
                                       -------------------------------------
                                        National Association Bylaws
                                       -------------------------------------
                                        Secretary
                                       -------------------------------------

TENANT:                       THE NORTHERN TRUST COMPANY

                              By:  /s/ Wayne LaChance
                                 -------------------------------------------

                              Title:  Vice President
                                    ----------------------------------------<PAGE>

                                                                 Exhibit 10(iii)
                           TWELFTH AMENDMENT TO LEASE
                           --------------------------

     This Twelfth Amendment to Lease (this "Amendment") is made as of August 28,
2000 by and between LaSalle Bank, N.A., as successor trustee to American
National Bank and Trust Company of Chicago, as Trustee under Trust Agreement
dated April 5, 1990 and known as Trust No. 110513-07 ("Landlord"), and The
Northern Trust Company, an Illinois banking corporation.

                                    Recitals
                                    --------

     A.  American National Bank and Trust Company of Chicago, as Trustee under
Trust No. 65287 ("Prior Landlord") and Tenant entered into that certain Lease
dated August 27, 1985 (the "Original Lease") as amended by that certain First
Amendment to Agreement of Lease dated August 15, 1986 (the "First Amendment"),
that certain Second Amendment to Agreement of Lease dated August 6, 1987 (the
"Second Amendment"), and that certain Third Amendment to Agreement of Lease
dated May 20, 1988 (the "Third Amendment").

     B.  The Original Lease, as amended by the First Amendment, Second Amendment
and Third Amendment, was assigned by Prior Landlord to Landlord by an assignment
dated April 6, 1990.

     C.  Landlord and Tenant further amended the Original Lease by that certain
Fourth Amendment to Agreement of Lease dated May 1, 1990, that certain Fifth
Amendment to Agreement of Lease dated January 12, 1995, that certain Sixth
Amendment to Agreement of Lease dated November 30, 1995 and that certain Seventh
Amendment dated February 24, 1998, (the "Seventh Amendment"), that certain
Eighth Amendment to Lease dated January 31, 2000, that certain Ninth Amendment
to Lease dated January 31, 2000, that certain Tenth Amendment to Lease dated
February 1, 2000 and that certain Eleventh Amendment to Lease dated August 1,
2000.  The Original Lease, as amended by all of the aforedescribed amendments,
is hereinafter referred to as the "Lease."  All capitalized terms used in this
Amendment and not otherwise defined shall have the meanings ascribed to them in
the Lease.

     D. Pursuant to the Lease, Tenant now leases from Landlord approximately
283,358 rentable square feet, (subject to the terms of the Tenth Amendment and
the Eleventh Amendment), in the building located at 181 West Madison Street,
Chicago, Illinois.

     E.  Landlord and Tenant have agreed to expand the Premises and wish to
confirm their agreements regarding such expansion in this Amendment.

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
contained herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant agree as
follows:

     1.  23rd Floor Expansion Space.  Effective as of the December 1, 2000 (the
"23rd Floor Expansion Space Commencement Date") and continuing until March 31,
2005 (such date, the "23rd Floor Expansion Space Expiration Date") (such period,
the "23rd Floor Expansion Space
<PAGE>

Term"), the Premises shall be expanded to include that certain space on the 23rd
floor of the Building, containing approximately 21,804 rentable square feet and
depicted on Exhibit A attached hereto and incorporated herein by this reference
(the "23rd Floor Expansion Space"). As of the 23rd Floor Expansion Space
Commencement Date, the Premises shall be deemed to contain, in the aggregate,
approximately 305,162 rentable square feet. From and after the date on which
Tenant executes and delivers this Amendment, Tenant shall have the right to
enter the 23rd Floor Expansion Space to make inspections and measurements of the
space. Notwithstanding anything to the contrary contained herein, but subject to
the conditions and requirements set forth in Paragraph 4 below, Tenant shall
have the right to enter the Premises and to begin to improve the 23rd Floor
Expansion Space for Tenant's purposes from and after the date on which this
Amendment is fully executed, in which event all of the provisions of the
Original Lease applicable to occupancy of premises shall apply and be in full
force and effect as to the 23rd Floor Expansion Space, other than, the
obligation to pay Rent, which shall commence on the 23rd Floor Expansion Space
Commencement Date. Notwithstanding the foregoing and the requirements set forth
in Paragraph 4 below, Tenant shall have the right to perform the demolition
portion of its tenant improvements to the 23rd Floor Expansion Space upon
Landlord's approval of Tenant's demolition plans and contractors performing such
work, which approval shall not be unreasonably withheld and which shall be given
(or denied, with specific reasons therefor) within three (3) business days of
Tenant's submission of such information to Landlord.

     2.  23rd Floor Expansion Space Base Rent.  Tenant shall pay Base Rent in
consideration for the leasing of the 23rd Floor Expansion Space for the 23rd
Floor Expansion Space Term, for the first sixteen (16) months of such term
(December 1, 2000 through March 31, 2002), at the annual rate of $21.75 per
square foot, or an Annual Base Rent of $474,237.00, in equal Monthly Base Rent
installments of $39, 519.75.  On April 1, 2002, and thereafter, on each April 1
throughout the 23rd Floor Expansion Space Term, such Base Rent shall increase by
three percent (3.0%) over the Base Rent in effect immediately prior to such
adjustment date.  Base Rent shall be paid promptly on the first day of each and
every calendar month during the 23rd Floor Expansion Space Term.

     3.  Rent Adjustments - Operating Expenses.  During the 23rd Floor Expansion
Space Term and with respect to the 23rd Floor Expansion Space, Tenant shall pay
Tenant's Proportionate Share of Operating Expenses and Operating Expense
Deposits as described in Paragraph 5 of the Original Lease.  Tenant's
Proportionate Share as to the 23rd Floor Expansion Space shall be 2.3737%.  No
Rent Adjustment (as described in Paragraph 5.B) shall be payable with respect to
the leasing of the 23rd Floor Expansion Space.

     4.  Condition of Space and Tenant Improvements.  Tenant agrees to accept
the 23rd  Floor Expansion Space in its "as is" condition as of the date of this
Amendment and agrees that Landlord has made no promise, representation or
agreement regarding any improvements, alterations or renovations of the 23rd
Floor Expansion Space, except that Landlord represents and warrants that, as of
the date of this Amendment, the current electrical service for the 23rd floor
includes a 600 amp main electrical switch.  Tenant shall be permitted to
construct leasehold improvements to such space, and Landlord will contribute an
allowance to the cost thereof, in accordance with the following provisions:
<PAGE>

          (a) Tenant shall, at Tenant's sole cost and expense (subject to the
     Allowance, as defined below), cause to be prepared and submitted to the
     Landlord for Landlord's prior approval, at such time as Tenant desires,
     plans and specifications (the "Tenant's Plans"), including, but not limited
     to, all space plans, working drawings, mechanical and engineering drawings
     disclosing all construction to be performed to build out the 23rd Floor
     Expansion Space. Landlord agrees to review and either approve or disapprove
     (and noting with such disapproval the specific items not approved) Tenant's
     Plans within five (5) business days of Landlord's receipt of a complete set
     of Tenant's Plans. In the event Tenant's Plans are disapproved, Tenant
     shall revise and resubmit Tenant's Plans expeditiously and Landlord shall
     review the same and notify the Tenant of its approval or disapproval within
     three (3) business days thereafter in the same manner as required for the
     initial submittal. Landlord's approval shall not be unseasonably withheld
     or delayed. Landlord's authorized representative ("Landlord's
     Representative") for the purpose of Tenant's deliveries or to
     communications to Landlord shall be the Building General Manager, at the
     management office located in the Building. Tenant shall not commence any
     work in the 23rd Floor Expansion Space until Tenant's Plans have been
     approved.

          (b) Tenant is hereby granted the right to utilize contractors of
     Tenant's own choice to build out the 23rd Floor Expansion Space, subject to
     Landlord's approval as to the qualifications of such contractor which shall
     not be unreasonably withheld. Landlord hereby approves Valenti, Turner
     Construction or Alter Construction. The contractor chosen by Tenant is
     hereinafter referred to as "Tenant's Contractor". All installations,
     alterations and additions shall be constructed in a good and workmanlike
     manner and only new and good grades of material shall be used. Such work
     performed by Tenant's Contractor shall comply with the Americans With
     Disabilities Act, and with all insurance requirements and all other
     ordinances and regulations of the City of Chicago or any department or
     agency thereof and with the requirements of all statutes and regulations of
     the State of Illinois or any department or agency thereof. Tenant shall
     permit Landlord's Representative (and an architect or engineer designated
     by Landlord) to observe all construction operations within the 23rd Floor
     Expansion Space performed by Tenant's Contractor, provided that no
     supervision fee shall be charged by Landlord. Such observation by persons
     on behalf of Landlord shall be solely and only for the benefit of Landlord.
     Tenant shall pay to the Landlord the cost of any materials purchased from
     Landlord at Landlord's actual invoice cost for said items. Tenant shall not
     be charged for hoisting. No silence or statement by any person acting on
     behalf of Landlord shall be deemed or construed as an assumption by said
     persons or Landlord of any responsibility for or in relation to the
     construction of the 23rd Floor Expansion Space or any guarantee that the
     work completed within the 23rd Floor Expansion Space complies with legal
     requirements, complies with Tenant's Plans, or is suitable or acceptable to
     the Tenant for Tenant's intended business purposes. Tenant shall furnish to
     Landlord, prior to commencement of any work in the 23rd Floor Expansion
     Space, building permits (or such other documentation as is required by the
     City of Chicago to commence such work) and certificates of appropriate
     insurance. Upon completion of any installations, alterations or additions,
     Tenant shall furnish Landlord with building permits (to the extent not
     previously required and furnished), and with contractor's affidavits and
     full and final waivers of lien covering all labor and material expended and
     used in constructing the 23rd
<PAGE>

     Floor Expansion Space. Tenant shall hold Landlord harmless and indemnify
     Landlord from all claims and costs, damages, liens and expenses which may
     arise out of or are connected in any way with said construction by Tenant's
     Contractor.

          (c) The cost of all work (the "Work") necessary to build out all of
     the 23rd Floor Expansion Space (including, but not limited to, all labor,
     material, permits and working drawings and design costs) shall, subject to
     the Allowance granted herein, be the responsibility of Tenant.  Landlord
     agrees to contribute an allowance of up to One Hundred Sixty-Six Thousand
     Eight Hundred and 60/100 Dollars ($166,800.60) (the "Allowance") toward the
     cost of the Work.  The Allowance shall be paid in one lump sum payment by
     Landlord to Tenant within ten (10) business days following Tenant's
     submission to Landlord of a contract or contracts evidencing that the cost
     of the Work equals or exceeds the amount of the Allowance.  As the Work
     progresses, Tenant shall require and collect, and submit copies to Landlord
     of, general contractor's statements, architect certificates (as to
     substantial completion of the stages of the Work as payments are being made
     therefor) and partial and final lien waivers, as the case may be, covering
     all Work (including design costs) for which the Allowance is being used to
     pay costs thereof.  Tenant shall be responsible for collecting and
     submitting to Landlord the final lien waivers from all contractors,
     subcontractors and materialmen involved in the Work.  If any mechanic lien
     is filed with respect to the Work, Tenant shall cause such lien to be
     discharged and removed from public record within thirty (30) days after
     such filing, or insure or bond over such lien to Landlord's reasonable
     satisfaction within such thirty (30) day period, failing which Landlord may
     take whatever steps are reasonably necessary to do so, at Tenant's sole
     cost and expense.

          (d) The 23rd Floor Expansion Space shall, upon expiration of the 23rd
     Floor Expansion Space Term, be left by Tenant in its then "as is"
     condition, broom clean and, notwithstanding anything to the contrary
     contained in the Lease, Landlord shall have no right to require Tenant to
     remove any of the improvements made to the 23rd Floor Expansion Space.

     5.  Brokers.  Tenant represents that, except for Douglas Elliman-Beitler
and Staubach Midwest, LLC, it has not dealt with any real estate brokers in
connection with this Twelfth Amendment and, to its knowledge, no broker other
than Douglas Elliman-Beitler and Staubach Midwest, LLC, initiated or
participated in the negotiation of this Twelfth Amendment, submitted or showed
the 23rd Floor Expansion Space or any other space in the Building to Tenant.
Notwithstanding the foregoing, no party is entitled to any commission or fee in
connection with the leasing of the 23rd Floor Expansion Space or the negotiation
of this Twelfth Amendment.  Tenant hereby agrees to indemnify, defend, and hold
Landlord harmless from and against any and all claims of any other party for
broker commission or fees in connection with this Twelfth Amendment who claim to
have dealt with the Tenant.

     Landlord represents that, except for Douglas Elliman-Beitler and Staubach
Midwest, LLC, it has not deal with any real estate brokers in connection with
this Twelfth Amendment and, to its knowledge, no broker other than Douglas
Elliman-Beitler and Staubach Midwest, LLC, initiated or participated in the
negotiation of this Twelfth Amendment, submitted or
<PAGE>

showed the 23rd Floor Expansion Space or any other space in the Building, on
behalf of Landlord, to Tenant. Notwithstanding the foregoing, no party is
entitled to any commission or fee in connection with the leasing of the 23rd
Floor Expansion Space or the negotiation of this Twelfth Amendment. Landlord
hereby agrees to indemnify, defend, and hold Tenant harmless from and against
any and all claims of Douglas Elliman-Beitler and Staubach Midwest, LLC and any
other party for broker commissions or fees in connection with this Twelfth
Amendment who claim to have dealt with the Landlord.

     6.  Merger.  All negotiations, considerations, representations and
understandings between Landlord and Tenant relating to this Twelfth Amendment
are incorporated herein and may be modified or altered only by agreement, in
writing, between Landlord and Tenant.  No modification, termination, or
surrender of the Lease, as modified by this Twelfth Amendment, or surrender of
the Premises (including the 23rd Floor Expansion Space) or any part thereof or
of any interest therein by Tenant shall be valid or effective unless agreed to
and accepted, in writing, by Landlord an no act by any representative or agent
of Landlord other than delivery of such a written agreement and acceptance by
Landlord shall constitute agreement to and acceptance thereof.  Any prior
negotiations or intentions of the parties relating to this Twelfth Amendment,
whether oral or evidenced by written documentation dated prior to the date of
this Twelfth Amendment, are null and void, unless specifically incorporated
herein by reference.

     7.  Exoneration Clause.  This Twelfth Amendment is executed by the
undersigned, LaSalle Bank, N.A., as successor trustee to American National Bank
and Trust Company of Chicago, not personally, but as Trustee in the exercise of
the power and authority conferred upon and vested in it as such Trustee and
under the express direction of the beneficiaries of the said Trust.  It is
expressly understood and agreed that all of the warranties, indemnities,
representations, covenants, undertaking sand agreements herein made on the part
of the Trustee are undertaken by it solely in its capacity as Trustee and not
personally.  No personal liability or personal responsibility is assumed by or
shall at any time be asserted or enforceable against the Trustee on account of
any warranty, indemnity, representation, covenant, undertaking or agreement of
the Trustee in this instrument.
<PAGE>

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

LANDLORD:                      LASALLE BANK, N.A., as Successor Trustee to
                               American National Bank and Trust Company of
                               Chicago, not individually, but solely as Trustee
                               under Trust Agreement dated April 5, 1990 and
                               known as Trust No. 110513-07

                               By:  /s/ David Rosenfeld
                                  ---------------------
                               Title: Assistant Vice President
                                     -------------------------

                               Attest: Attestation not required by LaSalle
                               Bank National Association Bylaws
                                                 ______________ Secretary

TENANT:                        THE NORTHERN TRUST COMPANY

                               By:  /s/ Wayne LaChance
                                  --------------------
                               Title: Vice President
                                     ---------------
<PAGE>

                                   EXHIBIT A
                                   ---------

                           23RD FLOOR EXPANSION SPACE
                           --------------------------

             (Diagram of 23rd Floor Expansion Space - 21,804 RSF)

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