Exhibit 10.1

UNITED STATES DEPARTMENT OF THE TREASURY

1500 PENNSYLVANIA AVENUE, NW

WASHINGTON, D.C. 20220

Dear Ladies and Gentlemen:

The company set forth on the signature page hereto (the “Company”) intends to
issue in a private placement the number of shares of a series of its preferred
stock set forth on Schedule A hereto (the “Preferred Shares”) and a warrant to
purchase the number of shares of its common stock set forth on Schedule A hereto
(the “Warrant” and, together with the Preferred Shares, the “Purchased
Securities”) and the United States Department of the Treasury (the “Investor”)
intends to purchase from the Company the Purchased Securities.

The purpose of this letter agreement is to confirm the terms and conditions of
the purchase by the Investor of the Purchased Securities. Except to the extent
supplemented or superseded by the terms set forth herein or in the Schedules
hereto, the provisions contained in the Securities Purchase Agreement – Standard
Terms attached hereto as Exhibit A (the “Securities Purchase Agreement”) are
incorporated by reference herein. Terms that are defined in the Securities
Purchase Agreement are used in this letter agreement as so defined. In the event
of any inconsistency between this letter agreement and the Securities Purchase
Agreement, the terms of this letter agreement shall govern.

Each of the Company and the Investor hereby confirms its agreement with the
other party with respect to the issuance by the Company of the Purchased
Securities and the purchase by the Investor of the Purchased Securities pursuant
to this letter agreement and the Securities Purchase Agreement on the terms
specified on Schedule A hereto.

This letter agreement (including the Schedules hereto) and the Securities
Purchase Agreement (including the Annexes thereto) and the Warrant constitute
the entire agreement, and supersede all other prior agreements, understandings,
representations and warranties, both written and oral, between the parties, with
respect to the subject matter hereof. This letter agreement constitutes the
“Letter Agreement” referred to in the Securities Purchase Agreement.

This letter agreement may be executed in any number of separate counterparts,
each such counterpart being deemed to be an original instrument, and all such
counterparts will together constitute the same agreement. Executed signature
pages to this letter agreement may be delivered by facsimile and such facsimiles
will be deemed as sufficient as if actual signature pages had been delivered.

* * *

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In witness whereof, this letter agreement has been duly executed and delivered
by the duly authorized representatives of the parties hereto as of the date
written below.

 

UNITED STATES DEPARTMENT OF THE TREASURY By:  

/s/ Neel Kashkari

Name:   Neel Kashkari Title:   Interim Assistant Secretary
for Financial Stability NORTHERN TRUST CORPORATION By:  

/s/ William R. Dodds, Jr.

Name:   William R. Dodds, Jr. Title:   Executive Vice President and Treasurer

Date: November 14, 2008

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EXHIBIT A

SECURITIES PURCHASE AGREEMENT

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SCHEDULE A

ADDITIONAL TERMS AND CONDITIONS

 

Company Information:   

Name of the Company:

   Northern Trust Corporation

Corporate or other organizational form:

   Corporation

Jurisdiction of Organization:

   Delaware

Appropriate Federal Banking Agency:

   Board of Governors of the Federal Reserve System

Notice Information:

  

Northern Trust Corporation

50 South LaSalle Street, M-9

Chicago, Illinois 60603

Attention: Corporate Secretary

Telephone: (312) 444-3714

Facsimile: (312) 444-4134

Terms of the Purchase:   

Series of Preferred Stock Purchased:

   Fixed Rate Cumulative Perpetual Preferred Stock, Series B

Per Share Liquidation Preference of Preferred Stock:

   $1,000

Number of Shares of Preferred Stock Purchased:

   1,576,000

Dividend Payment Dates on the Preferred Stock:

   February 15, May 15, August 15 and November 15

Number of Initial Warrant Shares:

   3,824,624

Exercise Price of the Warrant:

   $61.81

Purchase Price:

   $1,576,000,000 Closing:   

Location of Closing:

  

Simpson Thacher & Bartlett LLP

425 Lexington Avenue

New York, NY 10017

Time of Closing:

   9:00 a.m., New York time

Date of Closing:

   November 14, 2008

Wire Information for Closing:

  

ABA Number:

Bank:

Account Name:

Account Number:

Beneficiary:

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SCHEDULE B

CAPITALIZATION

 

Capitalization Date:    October 31, 2008 Common Stock   

Par value:

   $1.66 2/3

Total Authorized:

   560,000,000

Outstanding:

   223,077,269

Subject to warrants, options, convertible securities, etc.:

   18,013,332

Reserved for benefit plans and other issuances:

   21,041,115

Remaining authorized but unissued:

   336,922,731

Shares issued after Capitalization Date (other than pursuant to warrants,
options, convertible securities, etc. as set forth above):

   0 Preferred Stock   

Par value:

   Without par value

Total Authorized:

   10,000,000

Outstanding (by series):

   0

Reserved for issuance:

   1,500,000 shares of Series A Junior Participating Preferred Stock

Remaining authorized but unissued:

   8,500,000

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SCHEDULE C

REQUIRED STOCKHOLDER APPROVALS

 

     Required1    % Vote Required Warrants — Common Stock Issuance      

Charter Amendment

     

Stock Exchange Rules

     

If no stockholder approvals are required, please so indicate by checking the
box:  x.

 

1

If stockholder approval is required, indicate applicable class/series of capital
stock that are required to vote.

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SCHEDULE D

LITIGATION

List any exceptions to the representation and warranty in Section 2.2(l) of the
Securities Purchase Agreement – Standard Terms.

If none, please so indicate by checking the box:  x.

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SCHEDULE E

COMPLIANCE WITH LAWS

List any exceptions to the representation and warranty in the second sentence of
Section 2.2(m) of the Securities Purchase Agreement – Standard Terms.

If none, please so indicate by checking the box:  x.

List any exceptions to the representation and warranty in the last sentence of
Section 2.2(m) of the Securities Purchase Agreement – Standard Terms.

If none, please so indicate by checking the box:  x.

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SCHEDULE F

REGULATORY AGREEMENTS

List any exceptions to the representation and warranty in Section 2.2(s) of the
Securities Purchase Agreement – Standard Terms.

If none, please so indicate by checking the box:  x.