SECOND AMENDMENT TO LEASE

Exhibit 10(xi)(2)

SECOND AMENDMENT TO LEASE

This SECOND AMENDMENT TO LEASE ( this “ Agreement ”) is made and entered into as of the 13th day of April, 2005 between 181 WEST MADISON L.P. , a Delaware limited partnership (“ Landlord ”), successor to Davis West Madison LLC (“ Former Landlord ”), and THE NORTHERN TRUST COMPANY , an Illinois banking corporation (“ Tenant ”), with reference to the following:

R E C I T A L S :

A. LaSalle Bank National Association, 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 (“ Original Landlord ”), as landlord, and Tenant, as tenant, heretofore entered into a certain lease dated as of November 29, 2000 (the “ Original Lease ”), for certain premises (the “ Premises ”) in a building located on the real estate commonly known as 181 West Madison Street, Chicago, Illinois (the “ Building ”), as more particularly set forth in the Original Lease.

B. Original Landlord and Tenant heretofore modified the Original Lease by entering into those certain agreements listed on Exhibit C attached to and made a part of the Original Lease (each of such agreement being herein referred to as a “ Letter Agreement ” and all of such agreements collectively being referred to herein as the “ Letter Agreements ”). Former Landlord and Tenant heretofore entered into that certain First Amendment to Lease dated July 11, 2002 (the “ First Amendment to Lease ”). The Original Lease, as modified by the Letter Agreements and the First Amendment to Lease, is herein referred to as the “ Lease .”

C. Landlord has succeeded to all of Original Landlord’s and Former Landlord’s right, title and interest in and to the Lease.

D. Tenant is prepared to exercise its right to reduce the Premises in size pursuant to Section 45 of the Lease by deleting the full 19 ^th Floor (the “ Excluded 19 ^th Floor Premises ”) in the Building from the Premises, effective July 1, 2007, and is also prepared to yield up possession of the Excluded 19 ^th Floor Premises in advance of July 1, 2007, provided Landlord will agree to waive and release in full Tenant’s obligation to pay the second one-half (  ¹ / 2 ) of the Contraction Fee, as that term is defined in the Lease, applicable to the 19 ^th Floor (the Contraction Fee applicable to the Excluded 19 ^th Floor Premises, being referred to herein as the “ 19 ^th Floor Contraction Fee ”). A copy of Tenant’s intended Notice of Exercise of its Right of Contraction pertaining to the Excluded 19 ^th Floor Premises is attached to and made a part of this Agreement as Exhibit A .

E. Tenant is prepared to exercise its right to reduce the Premises in size pursuant to Section 45 of the Lease by deleting the full 18 ^th Floor (the “ Excluded 18 ^th Floor Premises ”) in the Building from the Premises, effective July 1, 2011, and is also prepared to yield up possession of the Excluded 18 ^th Floor Premises in advance of July 1, 2011, provided Landlord will agree to waive and release in full Tenant’s obligation to pay the second one-half (  ¹ / 2 ) of the Contraction Fee, as that term is defined in the Lease, applicable to the Excluded 18 ^th Floor Premises (the Contraction Fee applicable to the Excluded 18 ^th Floor Premises being referred to herein as the “ 18 ^th Floor Contraction Fee ”). A copy of Tenant’s intended Notice of Exercise of its Right of Contraction pertaining to the Excluded 18 ^th Floor Premises is attached to and made a part of this Agreement as Exhibit B .

F. Landlord and Tenant have agreed to resolve certain disputes between them about the accuracy of payments made by Tenant toward Tenant’s Proportionate Share of Operating Expenses for 2003.

G. All capitalized terms included in this Agreement shall have the identical meanings ascribed to them in the Original Lease.

NOW, THEREFORE , for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant agree as follows:

1. Incorporation . The Recital paragraphs set forth above are hereby incorporated herein as if fully set forth herein.

2. Contraction of 19 ^th Floor .

(a) If Tenant exercises its right to reduce the Premises in size by deleting the Excluded 19 ^th Floor Premises pursuant to a written notice in the form of Exhibit A (the “ 19 ^th Floor Contraction Notice ”) and otherwise in compliance with the requirements of Section 45 of the Lease, including without limitation, the payment to Landlord on exercise of the Contraction Option of the first one-half of the 19 ^th Floor Contraction Fee as defined in and in accordance with, the provisions contained in Section 45 of the Lease, then Landlord and Tenant agree as follows:

(i) Tenant shall continue to pay Rent and the other charges as and when due and payable under the Lease applicable to the Excluded 19 ^th Floor Premises to and including June 30, 2007 notwithstanding (1) Tenant’s exercise of its right to reduce the Premises by deleting the Excluded 19 ^th Floor Premises, (2) Landlord’s exercise of its right to require Tenant to deliver possession of the Excluded 19 ^th Floor Premises to Landlord prior to June 30, 2007, as provided in (b) below, and (3) Landlord’s entering into a lease with another party for all or any portion of the Excluded 19 ^th Floor Premises with a term commencing prior to July 1, 2007; and

(ii) The 19 ^th Floor Contraction Fee is estimated, as of the date hereof, to be $997,123.55 (the “ Estimated 19 ^th Floor Contraction Fee ”). (The calculation of the Estimated 19 ^th Floor Contraction Fee is shown on Exhibit D attached hereto.) Accordingly, if Tenant delivers the 19 ^th floor Contraction Notice, the payment of one-half of the 19 ^th Floor Contraction Fee to be made by Tenant concurrently with the delivery of such Contraction Notice shall be equal to $498,561.78. Landlord and Tenant hereby agree to recalculate the actual 19 ^th Floor Contraction Fee in accordance with the terms of Section 45 of the Lease on or about May 1, 2007. If one-half of the 19 ^th Floor Contraction Fee, as so recalculated, exceeds one-half of the Estimated 19 ^th Floor Contraction Fee, Tenant shall, within thirty (30) days after the date of such

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recalculation, pay to Landlord the amount of such excess. If one-half of the 19 ^th Floor Contraction Fee, as so recalculated, is less than one-half of the Estimated 19 ^th Floor Contraction Fee, Landlord shall, within thirty (30) days after the date of such recalculation, refund to Tenant the difference. If Landlord fails to refund such difference to Tenant within such thirty (30) day period, then Tenant may send Landlord a written demand for such refund, and if Landlord fails to pay such refund within ten (10) days after Landlord’s receipt of such written demand, Tenant shall be entitled to set off the amount of such refund against the rent next accruing under the Lease. Unless payment of the second half of the 19 ^th Floor Contraction Fee is waived as provided in this Section 2, the amount of the second half of the 19 ^th Floor Contraction Fee shall be one-half of the 19 ^th Floor Contraction Fee, as so recalculated.

(b) If Landlord, in its sole and absolute discretion, and irrespective of whether or not Tenant has delivered the 19 ^th Floor Contraction Notice, enters into a lease for all or a portion of the Excluded 19 ^th Floor Premises with a tenant acceptable to Landlord for a term commencing prior to July 1, 2007 and otherwise on terms satisfactory to Landlord in its sole and absolute discretion, and Landlord gives Tenant written notice (the “ 19 ^th Floor Early Possession Notice ”) that such lease has been executed and delivered and that Tenant must deliver to Landlord possession of the Excluded 19 ^th Floor Premises on a date specified by Landlord (the “ 19 ^th Floor Specified Date ”) occurring on or before June 30, 2007, then (i) Tenant shall deliver possession of the Excluded 19 ^th Floor Premises to Landlord in its “as is” condition on the 19 ^th Floor Specified Date, and (ii) Tenant shall continue to pay Rent and other charges as and when due and payable under the Lease applicable to the Excluded 19 ^th Floor Premises to and including June 30, 2007 notwithstanding (1) Landlord’s delivery of the 19 ^th Floor Early Possession Notice, or (2) Landlord’s entry into a Lease with another party for all or any portion of the Excluded 19 ^th Floor Premises with a term commencing prior to July 1, 2007. The 19 ^th Floor Specified Date shall be no sooner than two (2) business days after the date the 19 ^th Floor Early Possession Notice is delivered to Tenant.

(c) If Landlord delivers the 19 ^th Floor Early Possession Notice and Tenant so surrenders possession of the Excluded 19 ^th Floor Premises to Landlord by the 19 ^th Floor Specified Date and otherwise performs its obligations with respect to the exercise of the Contraction Option relating to the Excluded 19 ^th Floor Premises (including, without limitation, the payment of Rent and other charges as and when payable under the Lease applicable to the Excluded 19 ^th Floor Premises to and including June 30, 2007), then Landlord agrees that Tenant’s obligation to pay the second one-half (  ¹ / 2 ) of the 19 ^th Floor Contraction Fee shall be waived and released in full and of no further force and effect. If Landlord does not deliver the 19 ^th Floor Early Possession Notice, or if Tenant does not perform its obligations as set forth in the immediately preceding sentence, then Tenant shall remain obligated to pay the second one-half of the 19 ^th Floor Contraction Fee.

(d) If Tenant delivers the 19 ^th Floor Contraction Notice or Landlord delivers the 19 ^th Floor Early Possession Notice, then, (1) effective as of the date of delivery of either such notice, the Second Expansion Option (as defined in Section 52 of the Original Lease) shall be deemed terminated, void and without further force or effect, Tenant’s exercise of its Contraction Option

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for the Exclusion Date of July 1, 2007 shall be deemed exercised, and the 19 ^th Floor of the Building shall no longer be deemed part of the First Offer Space (as defined in Section 51 of the Original Lease), and (2) Landlord and Tenant shall promptly enter into an amendment to the Lease to reflect the termination of the Lease with respect to the Excluded 19 ^th Floor Premises.

(e) Section 48A(iv) of the Original Lease, as amended by Section 3 of the First Amendment to Lease, grants Tenant an allowance (the “ 19 ^th Floor Put Space Allowance ”) of up to $774,655.00 (i.e., $35.00 per square foot of Rentable Area of the portion of the Premises located on the 19 ^th Floor of the Building) to reimburse Tenant for certain tenant improvement costs incurred by Tenant in connection with such portion of the Premises, as more particularly described in such Section 48A(iv) of the Original Lease. Landlord acknowledges that, as of the date of this Amendment, Landlord has not disbursed any portion of the 19 ^th Floor Put Space Allowance. Landlord hereby agrees that if the Lease with respect to the Excluded 19 ^th Floor Premises terminates as provided above in this Section 2 before all of the 19 ^th Floor Put Space Allowance has been disbursed to Tenant, any portion of the 19 ^th Floor Put Space Allowance not so disbursed shall, so long as Tenant is not then in default under the Lease beyond applicable periods of notice and cure, be available to be disbursed to Tenant in accordance with the terms of Section 48A(iv) of the Original Lease for tenant improvement work performed by Tenant in other portions of the Premises.

3. Contraction of 18 ^th Floor .

(a) If Tenant exercises its right to reduce the Premises in size by deleting the Excluded 18 ^th Floor Premises pursuant to a written notice in the form of Exhibit B (the “ 18 ^th Floor Contraction Notice ”) and otherwise in compliance with the requirements of Section 45 of the Lease, including without limitation, the payment to Landlord on exercise of the Contraction Option of the first one-half of the 18 ^th Floor Contraction Fee as defined in and in accordance with, the provisions contained in Section 45 of the Lease, then Landlord and Tenant agree as follows:

(i) Tenant shall continue to pay Rent and the other charges as and when due and payable under the Lease applicable to the Excluded 18 ^th Floor Premises to and including June 30, 2011 notwithstanding (1) Tenant’s exercise of its right to reduce the Premises by deleting the Excluded 18 ^th Floor Premises, (2) Landlord’s exercise of its right to require Tenant to deliver possession of the Excluded 18 ^th Floor Premises to Landlord prior to June 30, 2011, as provided in (b) below, and (3) Landlord’s entering into a lease with another party for all or any portion of the Excluded 19 ^th Floor Premises with a term commencing prior to July 1, 2011; and

(ii) The 18 ^th Floor Contraction Fee is estimated, as of the date hereof, to be $1,079,186.84 (the “ Estimated 18 ^th Floor Contraction Fee ”). (The calculation of the Estimated 18 ^th Floor Contraction Fee is shown on Exhibit D attached hereto.) Accordingly, if Tenant delivers the 18 ^th Floor Contraction Notice, the payment of one-half of the 18 ^th Floor

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Contraction Fee to be made by Tenant concurrently with the delivery of such 18 ^th Floor Contraction Notice shall be equal to $539,593.42. Landlord and Tenant hereby agree to recalculate the actual 18 ^th Floor Contraction Fee in accordance with the terms of Section 45 of the Lease on or about May 1, 2011. If one-half of the 18 ^th Floor Contraction Fee, as so recalculated, exceeds one-half of the Estimated 18 ^th Floor Contraction Fee, Tenant shall, within thirty (30) days after the date of such recalculation, pay to Landlord the amount of such excess. If one-half of the Contraction Fee applicable to the Excluded 18 ^th Floor Premises, as so recalculated, is less than one-half of the Estimated 18 ^th Floor Contraction Fee, Landlord shall, within thirty (30) days after the date of such recalculation, refund to Tenant the difference. If Landlord fails to refund such difference to Tenant within such thirty (30) day period, then Tenant may send Landlord a written demand for such refund, and if Landlord fails to pay such refund within ten (10) days after Landlord’s receipt of such written demand, Tenant shall be entitled to set off the amount of such refund against the rent next accruing under the Lease. Unless payment of the second half of the 18 ^th Floor Contraction Fee is waived as provided in this Section 3, the amount of the second half of the 18 ^th Floor Contraction Fee shall be one-half of the 18 ^th Floor Contraction Fee, Floor Premises as so recalculated.

(b) If Landlord, in its sole and absolute discretion, enters into a lease for all or a portion of the Excluded 18 ^th Floor Premises with a tenant acceptable to Landlord for a term commencing prior to July 1, 2011 and otherwise on terms satisfactory to Landlord in its sole and absolute discretion, and Landlord gives Tenant written notice (the “ 18 ^th Floor Early Possession Notice ”) that such lease has been executed and delivered and that Tenant must deliver to Landlord possession of the Excluded 18 ^th Floor Premises on a date specified by Landlord (the “ 18 ^th Floor Specified Date ”) occurring on or before June 30, 2011, then (i) Tenant shall deliver possession of the Excluded 18 ^th Floor Premises to Landlord in its “as is” condition on the 18 ^th Floor Specified Date, and (ii) Tenant shall continue to pay Rent and other charges as and when due and payable under the Lease applicable to the Excluded 18 ^th Floor Premises to and including June 30, 2011 notwithstanding (1) Landlord’s delivery of the 18 ^th Floor Early Possession Notice, or (2) Landlord’s entry into a Lease with another party for all or any portion of the Excluded 18 ^th Floor Premises with a term commencing prior to July 1, 2011. The 18 ^th Floor Specified Date shall be no sooner than two (2) business days after the date the Early Possession Notice is delivered to Tenant; and

(c) If Landlord delivers the 18 ^th Floor Early Possession Notice and Tenant so surrenders possession of the Excluded 18 ^th Floor Premises to Landlord by the 18 ^th Floor Specified Date and otherwise performs its obligations with respect to the exercise of the Contraction Option relating to the Excluded 18 ^th Floor Premises (including, without limitation, the payment of Rent and other charges as and when payable under the Lease applicable to the Excluded 18 ^th Floor Premises to and including June 30, 2011), then Landlord agrees that Tenant’s obligation to pay the second one-half (  ¹ / 2 ) of the 18 ^th Floor Contraction Fee shall be waived and released in full and of no further force and effect. If Landlord does not deliver the 18 ^th Floor Early Possession Notice, or if Tenant does not perform its obligations as set forth in the immediately preceding sentence, then Tenant shall remain obligated to pay the second one-half of the 18 ^th Floor Contraction Fee.

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(d) If Tenant delivers the 18 ^th Floor Contraction Notice, or if Landlord delivers the 18 ^th Floor Early Possession Notice, then, (1) effective as of the date of delivery of either such notice, the Third Expansion Option (as defined in Section 52 of the Original Lease) shall be deemed terminated, void and without further force or effect, Tenant’s exercise of its Contraction Option for the Exclusion Date of July 1, 2011 shall be deemed exercised, and the 18 ^th Floor of the Building shall no longer be deemed part of the First Offer Space (as defined in Section 51 of the Original Lease), and (2) Landlord and Tenant shall promptly enter into an amendment to the Lease to reflect the termination of the Lease with respect to the Excluded 18 ^th Floor Premises.

(e) Section 48A(iv) of the Original Lease, as amended by Section 3 of the First Amendment to Lease, grants Tenant an allowance (the “ 18 ^th Floor Put Space Allowance ”) of up to $746,585.00 (i.e., $35.00 per square foot of Rentable Area of the portion of the Premises located on the 18 ^th Floor of the Building) to reimburse Tenant for certain tenant improvement costs incurred by Tenant in connection with such portion of the Premises, as more particularly described in such Section 48A(iv) of the Original Lease. Landlord acknowledges that, as of the date of this Amendment, Landlord has not disbursed any portion of the 18 ^th Floor Put Space Allowance. Landlord hereby agrees that if the Lease with respect to the Excluded 18 ^th Floor Premises terminates as provided above in this Section 3 before all of the 18 ^th Floor Put Space Allowance has been disbursed to Tenant, any portion of the 18 ^th Floor Put Space Allowance not so disbursed shall, so long as Tenant is not then in default under the Lease beyond applicable periods of notice and cure, be available to be disbursed to Tenant in accordance with the terms of Section 48A(iv) of the Original Lease for tenant improvement work performed by Tenant in other portions of the Premises.

4. Expansion Space . The second sentence of Section 4A of the First Amendment is hereby deleted in its entirety and replaced with the following: “In lieu thereof, and notwithstanding anything to the contrary contained in said Section 52, Landlord, within ten (10) days following its receipt of written notice from Tenant of Tenant’s exercise of the applicable Expansion Option, shall designate a floor of the Building (on any of the 17 ^th through 39 ^th floors of the Building, both inclusive) which will serve as the applicable Expansion Space and the date upon which Landlord will make such Expansion Space available to Tenant notwithstanding the Expansion Space Commencement Date set forth in the Original Lease.”

5. Right of First Offer to Lease . Tenant hereby agrees that, effective as of the date hereof, the 38 ^th Floor of the Building shall no longer be included in the First Offer Space, as defined in Section 51 of the Original Lease.

6. Tenant’s Proportionate Share of Operating Expenses .

(a) Landlord hereby agrees to credit for the account of Tenant against the next payments of Rent due under the Lease, the amount of $245,104.00 (the “ Rent Credit ”), as a full and complete settlement of Tenant’s claims that it overpaid Tenant’s Proportionate Share of Operating Expenses for Calendar Year 2003. Such agreement by Landlord is not intended to be, and shall not be construed as being, an admission that Landlord overcharged Tenant for Tenant’s Proportionate Share of Operating Expenses for Calendar Year 2003 or any other Calendar Year.

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(b) Tenant, for itself, and for its successors and assigns, in consideration of the Rent Credit and Landlord’s other agreements in this Section 6, hereby waives its right to dispute the accuracy of any payments made by Tenant toward Tenant’s Proportionate Share of Operating Expenses for any period prior to January 1, 2004, including, without limitation, any claim against Landlord as a result of alleged overcharges of Tenant’s share of 2003 Operating Expenses identified in connection with the audit of Landlord’s Operating Expenses for the Calendar Year 2003 conducted by Tenant’s agent, The Robert Thomas Group, as set forth in detail in that certain letter from The Robert Thomas Group dated September 28, 2004 addressed to Andrew Bartucci, General Manager of MB Real Estate, which is attached to and made a part of this Agreement as Exhibit E (the “ Audit ”). Landlord and Tenant agree that the calculation shown on Exhibit F is an accurate “gross up” of Operating Expenses for 2003.

(c) Effective as of January 1, 2004, and continuing for the remainder of the Term of the Lease, Operating Expenses under the Lease shall be “grossed up” in accordance with the example shown on Exhibit G attached hereto.

(d) Tenant shall keep the terms of this Section 6 and the Audit confidential and shall not disclose such terms or the Audit to any other party, except for Tenant’s employees and professional advisors who have a business need to know of such terms or the Audit, and Tenant shall cause its employees and professional advisors to keep such terms and the Audit confidential and to not disclose them to others.

7. Integration of Lease and Controlling Language . This Agreement and the Lease shall be deemed to be, for all purposes, one instrument. In the event of any conflict between the terms and provisions of this Agreement and the terms and provisions of the Lease, the terms and provisions of this Agreement, in all instances, shall control and prevail.

8. Severability . If any provision of this Agreement or the application thereof to any person or circumstance is or shall be deemed illegal, invalid of unenforceable, the remaining provisions hereof shall remain in full force and effect and this Agreement shall be interpreted as if such illegal, invalid or unenforceable provision did not exist herein.

9. Entire Agreement . This Agreement and the Lease contain the entire integrated agreement between the parties respecting the subject matter of this Agreement and the Lease and supersede all prior and contemporaneous understandings and agreements, other than the Lease, between the parties respecting the subject matter of this Agreement and the Lease. There are no representations, agreements, arrangements or understandings, oral or in writing, between or among the parties to this Agreement relating to the subject matter of this Agreement or the Lease which are not fully expressed in this Agreement and the Lease, and no party hereto has relied upon any other such representations, agreements, arrangements or understandings. The terms of this Agreement and the Lease are intended by the parties as the final expression of their agreement with respect to those terms and may not be contradicted by evidence or any prior agreement or of any contemporaneous agreement. The parties further intend that no extrinsic evidence whatsoever may be introduced in any judicial proceeding involving this Agreement.

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10. Successors and Assigns . Each provision of the Lease and this Agreement shall extend to and shall bind and inure to the benefit of Landlord and Tenant, their respective legal representatives, successors and assigns.

11. Time of the Essence . Time is of the essence of this Agreement and the Lease and each provision hereof.

12. Multiple Counterparts . This Agreement may be executed in counterparts, each of which shall be deemed to be an original and all of which shall together constitute one and the same instrument.

13. Authority . Landlord and Tenant each represent and warrant that it has full authority to execute and deliver this Agreement.

14. Ratification . Except as amended and modified hereby, the Lease shall be and shall remain unchanged and in full force and effect in accordance with its terms, and, as the Lease is amended and modified hereby, the Lease is hereby ratified, adopted and confirmed.

15. Limitation of Landlord’s Liability . The obligations of Landlord under the Lease as amended by this Amendment do not constitute personal obligations of the individual partners, members, directors, officers, shareholders, trustees or beneficiaries of Landlord, and Tenant shall not seek recourse against the partners, members, directors, officers, shareholders, trustees or beneficiaries of Landlord, or any of their personal assets for satisfaction of any liability with respect to the Lease as amended by this Amendment. In the event of any default by Landlord under the Lease as amended by this Amendment, Tenant’s sole and exclusive remedy shall be against Landlord’s interest in the Building and the real property on which it is located. The provisions of this paragraph are not designed to relieve Landlord from the performance of any of its obligations hereunder, but rather to limit Landlord’s liability in the case of the recovery of a judgment against it, as aforesaid, nor shall any of the provisions of this paragraph be deemed to limit or otherwise affect Tenant’s right to obtain injunctive relief or specific performance or availability of any other right or remedy which may be accorded Tenant by law or the Lease. In the event of sale or other transfer of Landlord’s right, title and interest in the Building, Landlord shall be released from all liability and obligations thereafter accruing under the Lease as amended by this Amendment; provided, that this paragraph shall inure to the benefit of any such purchaser or transferee.

[SIGNATURE PAGE FOLLOWS]

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IN WITNESS WHEREOF , Landlord and Tenant have executed this Second Amendment to Lease as of the day and year first above written.

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EXHIBIT A

NOTICE OF EXERCISE OF TENANT’S RIGHT

OF CONTRACTION PERTAINING TO 19TH FLOOR,

AT 181 WEST MADISON STREET, CHICAGO, ILLINOIS

                     , 200     

VIA FEDERAL EXPRESS

181 West Madison L.P.

c/o MB Real Estate

181 West Madison Street

Chicago, Illinois 60602

Gentlemen:

The Northern Trust Company (“ Tenant ”) and 181 West Madison L.P. (“ Landlord ”) are parties to a Lease dated November 21, 2000 as amended (“ Lease ”) for office space (“ Premises ”) in the Office Building (“ Building ”) located on the real estate commonly known as 181 West Madison Street, Chicago, Illinois.

Tenant hereby gives notice to Landlord pursuant to Section 45 of the Lease (captioned, “ Contraction Option ”) of Tenant’s exercise of its right to reduce the Premises in size by deleting the full 19 ^th Floor (“ Excluded Premises ”) in the Building from the Premises, effective the first listed Exclusion Date, which is July 1, 2007.

Pursuant to Paragraph E. of Section 45 of the Lease and Section 2 to the Second Amendment to Lease dated April           , 2005 (the “ Second Amendment ”), Tenant hereby tenders to Landlord with this Notice, its check payable to Landlord in the amount of $498,561.78 which amount represents Tenant’s computation of one-half (1/2) of the Contraction Fee to be paid to Landlord on Tenant’s exercise of its Contraction Option and is subject to adjustment as provided in Section 2 of the Second Amendment. The computation was prepared in accordance with the provisions set forth in Paragraph E. of Section 45 of the Lease.

Please acknowledge receipt of this Notice of Exercise and the check referred to therein by your signature on the duplicate copy of the Notice of Exercise enclosed.

A-1

A-2

EXHIBIT B

NOTICE OF EXERCISE OF TENANT’S RIGHT

OF CONTRACTION PERTAINING TO 18TH FLOOR,

AT 181 WEST MADISON STREET, CHICAGO, ILLINOIS

                     , 200     

VIA FEDERAL EXPRESS

181 West Madison L.P.

c/o MB Real Estate

181 West Madison Street

Chicago, Illinois 60602

Gentlemen:

The Northern Trust Company (“ Tenant ”) and 181 West Madison L.P. (“ Landlord ”) are parties to a Lease dated November 21, 2000 as amended (“ Lease ”) for office space (“ Premises ”) in the Office Building (“ Building ”) located on the real estate commonly known as 181 West Madison Street, Chicago, Illinois.

Tenant hereby gives notice to Landlord pursuant to Section 45 of the Lease (captioned, “ Contraction Option ”) of Tenant’s exercise of its right to reduce the Premises in size by deleting the full 18 ^th Floor (“ Excluded Premises ”) in the Building from the Premises, effective the second listed Exclusion Date, which is July 1, 2011.

Pursuant to Paragraph E. of Section 45 of the Lease and Section 3 to the Second Amendment to Lease dated April           , 2005 (the “ Second Amendment ”), Tenant hereby tenders to Landlord with this Notice, its check payable to Landlord in the amount of $539,593.42 which amount represents Tenant’s computation of one-half (1/2) of the Contraction Fee to be paid to Landlord on Tenant’s exercise of its Contraction Option and is subject to adjustment as provided in Section 3 of the Second Amendment. The computation was prepared in accordance with the provisions set forth in Paragraph E. of Section 45 of the Lease.

Please acknowledge receipt of this Notice of Exercise and the check referred to therein by your signature on the duplicate copy of the Notice of Exercise enclosed.

B-1