QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.3

AMENDMENT TO CREDIT AGREEMENT

        THIS AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is made as of
October 4, 2007, by and among SIMON PROPERTY GROUP, L.P., a Delaware limited
partnership (the "Borrower"), the LENDERS listed on the signature pages hereof,
JPMORGAN CHASE BANK, N.A., as Administrative Agent, DEUTSCHE BANK
SECURITIES, INC., as Co-Documentation Agent, THE BANK OF NOVA SCOTIA, NEW YORK
AGENCY, as Co-Documentation Agent, and SUMITOMO MITSUI BANKING CORPORATION, as
Co-Documentation Agent, and UBS SECURITIES LLC, as Joint Syndication Agent, BANK
OF AMERICA, N.A., as Joint Syndication Agent, and CITICORP NORTH AMERICA INC.,
as Joint Syndication Agent.

WITNESSETH:

        WHEREAS, the Borrower and the Lenders have entered into the Credit
Agreement, dated as of December 15, 2005 (the "Credit Agreement"); and

        WHEREAS, the Borrower has exercised its option pursuant to
Section 2.1(d) of the Credit Agreement; and

        WHEREAS, the parties desire to modify the Credit Agreement upon the
terms and conditions set forth herein.

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

1.Definitions.    All capitalized terms not otherwise defined herein shall have
the meanings ascribed to them in the Credit Agreement.

2.Amendments to Definitions. (a)The definition of "Managing Agents" is hereby
amended by adding after T.M. Life Insurance Company", the following: "and
Norddeutsche Landesbank Girozentrale, New York Branch, Aareal Bank AG and
Goldman Sachs Bank USA"

(b)The definition of "Revolving Credit Commitment" is hereby deleted and the
following substituted therefor:

"Revolving Credit Commitment" means, with respect to any Lender, the obligation
of such Lender to make Committed Loans and to participate in Letters of Credit
pursuant to the terms and conditions of this Agreement, and which shall not
exceed the sum of the principal amount set forth opposite such Lender's name
under the heading "Revolving Credit Commitment" and "Alternative Currency
Commitment" on Schedule 1.1 attached to the Amendment to Credit Agreement, dated
as of October 4, 2007 or the signature page of the Assignment and Acceptance by
which it became a Lender, as modified from time to time pursuant to the terms of
this Agreement or to give effect to any applicable Assignment and Acceptance,
and "Revolving Credit Commitments" means the aggregate principal amount of the
Revolving Credit Commitments and Alternative Currency Commitments of all the
Lenders, the maximum amount of which shall be $3,500,000,000, as reduced from
time to time pursuant to Section 4.1.

3.Other Amendments.    Section 2.1(d) and all references thereto are hereby
deleted in their entirety.

4.Effective Date.    This Amendment shall become effective upon receipt by the
Administrative Agent of (i) counterparts hereof signed by the Borrower and each
existing Lender that has elected to increase its Revolving Credit Commitment and
each institution (which shall be an Eligible Assignee) that has elected to
become a Lender, and (ii) payment by Borrower of the agreed upon fees for the
account of the Lenders increasing their Revolving Credit Commitments and new
institutions becoming Lenders (the date of such receipt being deemed the
"Effective Date").

--------------------------------------------------------------------------------

5.Representations and Warranties.    Borrower hereby represents and warrants
that as of the Effective Date, all the representations and warranties set forth
in the Credit Agreement, as amended hereby, are true and complete in all
material respects.

6.Entire Agreement.    This Amendment constitutes the entire and final agreement
among the parties hereto with respect to the subject matter hereof and there are
no other agreements, understandings, undertakings, representations or warranties
among the parties hereto with respect to the subject matter hereof except as set
forth herein.

7.Governing Law.    This Amendment shall be governed by, and construed in
accordance with, the law of the State of New York.

8.Counterpart.    This Amendment may be executed in any number of counterparts,
all of which taken together shall constitute one and the same agreement, and any
of the parties hereto may execute this Amendment by signing any such
counterpart.

9.Headings Etc.    Section or other headings contained in this Amendment are for
reference purposes only and shall not in any way affect the meaning or
interpretation of this Amendment.

10.No Further Modifications.    Except as modified herein, all of the terms and
conditions of the Credit Agreement, as modified hereby shall remain in full
force and effect and, as modified hereby, the Borrower confirms and ratifies all
of the terms, covenants and conditions of the Credit Agreement in all respects.

        IN WITTIESS WHEREOF, this Amendment has been duly executed as of the
date first above written.

BORROWER: SIMON PROPERTY GROUP, L.P.,
a Delaware limited partnership
 
By:
 
SIMON PROPERTY GROUP, INC.,
as Managing General Partner
 
By:
 
/s/  DAVID SIMON      

--------------------------------------------------------------------------------

Chief Executive Officer

--------------------------------------------------------------------------------

ADMINISTRATIVE AGENT AND LENDER:   JPMORGAN CHASE BANK, N.A.
 
 
By:
 
/s/  MARC COSTANTINO      

--------------------------------------------------------------------------------

    Name:   Marc Costantino     Title:   Executive Director

--------------------------------------------------------------------------------

SYNDICATION AGENT AND LENDER:   UBS LOAN FINANCE, LLC
 
 
By:
 
/s/  IRJA R. OTSA      

--------------------------------------------------------------------------------

    Name:   Irja R. Otsa     Title:   Associate Director Banking Products
Services, US
 
 
By:
 
/s/  DAVID B. JULIE      

--------------------------------------------------------------------------------

    Name:   David B. Julie     Title:   Associate Director Banking Products
Services, US
Revolving Credit Commitment: $106,765,625
Alternative Currency Commitment: $43,234,375

--------------------------------------------------------------------------------

SYNDICATION AGENT AND LENDER:   CITICORP NORTH AMERICA, INC.
 
 
By:
 
/s/  RICARDO JAMES      

--------------------------------------------------------------------------------

    Name:   Ricardo James     Title:   SCO 2 Real Estate Estate Industry
Specialist
Revolving Credit Commitment: $106,765,625
Alternative Currency Commitment: $43,234,375

--------------------------------------------------------------------------------

CO-DOCUMENTATION AGENT AND LENDER:   DEUTSCHE BANK AG, NEW YORK BRANCH
 
 
By:
 
/s/  BRENDA CASEY      

--------------------------------------------------------------------------------

    Name:   Brenda Casey     Title:   Director
 
 
By:
 
/s/  J.T. JOHNSTON COE      

--------------------------------------------------------------------------------

    Name:   J.T. Johnston Coe     Title:   Managing Director
Revolving Credit Commitment: $103,015,625
Alternative Currency Commitment: $41,984,375

--------------------------------------------------------------------------------

CO-DOCUMENTATION AGENT AND LENDER:   THE BANK OF NOVA SCOTIA, NEW YORK AGENCY
 
 
By:
 
/s/  ROBERT BOESE      

--------------------------------------------------------------------------------

    Name:   Robert Boese     Title:   Managing Director
Revolving Credit Commitment: $95,515,625
Alternative Currency Commitment: $39,484,375

--------------------------------------------------------------------------------

CO-DOCUMENTATION AGENT AND LENDER:   SUMITOMO MITSUI BANKING CORPORATION
 
 
By:
 
/s/  WILLIAM M. GINN      

--------------------------------------------------------------------------------

    Name:   William M. Ginn     Title:   General Manager
Revolving Credit Commitment: $99,265,625
Alternative Currency Commitment: $40,734,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   THE ROYAL BANK OF SCOTLAND PLC
 
 
By:
 
/s/  BRETT THOMPSON      

--------------------------------------------------------------------------------

    Name:   Brett Thompson     Title:   Vice President
Revolving Credit Commitment: $92,265,625
Alternative Currency Commitment: $37,734,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   CALYON NEW YORK BRANCH
 
 
By:
 
/s/  WILLIAM J. ROGERS      

--------------------------------------------------------------------------------

    Name:   William J. Rogers     Title:   Managing Director
 
 
By:
 
/s/  PAUL T. RAGUSIN      

--------------------------------------------------------------------------------

    Name:   Paul T. Ragusin     Title:   Director
Revolving Credit Commitment: $84,765,625
Alternative Currency Commitment: $35,234,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   CREDIT SUISSE, CAYMAN ISLANDS
BRANCH
 
 
By:
 
/s/  CASSANDRA DROOGAN      

--------------------------------------------------------------------------------

    Name:   Cassandra Droogan     Title:   Vice President
 
 
By:
 
/s/  SHAHEEN MALIK      

--------------------------------------------------------------------------------

    Name:   Shaheen Malik     Title:   Associate
Revolving Credit Commitment: $88,515,625
Alternative Currency Commitment: $36,484,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   MERRILL LYNCH BANK USA
 
 
By:
 
/s/  LOUIS ALDER      

--------------------------------------------------------------------------------

    Name:   Louis Alder     Title:   Director
Revolving Credit Commitment: $88,515,625
Alternative Currency Commitment: $36,484,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   MORGAN STANLEY BANK
 
 
By:
 
/s/  DANIEL TWENGE      

--------------------------------------------------------------------------------

    Name:   Daniel Twenge     Title:   Authorized Signatory
Revolving Credit Commitment: $88,515,625
Alternative Currency Commitment: $36,484,375

--------------------------------------------------------------------------------

SENIOR EXECUTIVE MANAGING AGENT AND LENDER:   PNC BANK, NATIONAL ASSOCIATION
 
 
By:
 
/s/  TERRI A. WYDA      

--------------------------------------------------------------------------------

    Name:   Terri A. Wyda     Title:   Vice President
Revolving Credit Commitment: $77,265,625
Alternative Currency Commitment: $32,734,375

--------------------------------------------------------------------------------

SENIOR MANAGING AGENT AND LENDER:   NATIONAL CITY BANK
 
 
By:
 
/s/  JOHN J. THULLEN      

--------------------------------------------------------------------------------

    Name:   John J. Thullen     Title:   Senior Vice President
Revolving Credit Commitment: $75,000,000
Alternative Currency Commitment: $25,000,000

--------------------------------------------------------------------------------

SENIOR MANAGING AGENT AND LENDER:   SUNTRUST BANK
 
 
By:
 
/s/  NANCY B. RICHARDS      

--------------------------------------------------------------------------------

    Name:   Nancy B. Richards     Title:   Senior Vice Prcsident
Revolving Credit Commitment: $60,000,000
Alternative Currency Commitment: $20,000,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   KBC BANK N.V.
 
 
By:
 
/s/  FRANCIS X. PAYNE      

--------------------------------------------------------------------------------

    Name:   Francis X. Payne     Title:   Vice President
 
 
By:
 
/s/  THOMAS R. LALLI      

--------------------------------------------------------------------------------

    Name:   Thomas R. Lalli     Title:   First Vice President
Revolving Credit Commitment: $45,000,000
Alternative Currency Commitment: $15,000,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   UNION BANK OF CALIFORNIA, N.A
 
 
By:
 
/s/  DAVID B. MURPHY      

--------------------------------------------------------------------------------

    Name:   David B. Murphy     Title:   SVP/Regional Mgr.
Revolving Credit Commitment: $45,000,000
Alternative Currency Commitment: $15,000,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   LANDESBANK BADEN-WURTTEMBERG
NEW YORK BRANCH
 
 
By:
 
/s/  LEONARD J. CRANN      

--------------------------------------------------------------------------------

    Name:   Leonard J. Crann     Title:   Head of Real Estate Finance Department
 
 
By:
 
/s/  ROBERT DOWLING      

--------------------------------------------------------------------------------

    Name:   Robert Dowling     Title:   Vice President
Sr. Marketing Officer
Revolving Credit Commitment: $48,750,000
Alternative Currency Commitment: $16,250,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   BANK OF TOKYO—MITSUBISHI UFJ, LTD.
 
 
By:
 
/s/  JAMES T. TAYLOR      

--------------------------------------------------------------------------------

    Name:   James T. Taylor     Title:   Vice President
Revolving Credit Commitment: $45,000,000
Alternative Currency Commitment: $15,000,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   AAREAL BANK AG
 
 
By:
 
/s/  MICHAEL GREVE      

--------------------------------------------------------------------------------

    Name:   Michael Greve     Title:   Manager
 
 
By:
 
/s/  K. PEETERMANS      

--------------------------------------------------------------------------------

    Name:   K. Peetermans     Title:   Legal Counsel
Revolving Credit Commitment: $22,500,000
Alternative Currency Commitment: $7,500,000

--------------------------------------------------------------------------------

MANAGING AGENT AND LENDER:   GOLDMAN SACHS BANK USA
 
 
By:
 
/s/  WILLIAM YARBENET      

--------------------------------------------------------------------------------

    Name:   William Yarbenet     Title:   Vice President
Revolving Credit Commitment: $22,500,000
Alternative Currency Commitment: $7,500,000

--------------------------------------------------------------------------------

LENDER:   PEOPLE'S UNITED BANK
 
 
By:
 
/s/  MAURICE FRY      

--------------------------------------------------------------------------------

    Name:   Maurice Fry     Title:   Vice President
Revolving Credit Commitment: $25,000,000
Alternative Currency Commitment: $0

--------------------------------------------------------------------------------

SCHEDULE 1.1

Lender

--------------------------------------------------------------------------------

  Revolving Credit Commitment

--------------------------------------------------------------------------------

  Alternative Currency Commitment

--------------------------------------------------------------------------------

JPMorgan Chase Bank, N.A.    $ 89,765,625   $ 42,734,375 Bank of America, N.A. 
  $ 89,765,625   $ 42,734,375 Citicorp North America, Inc.    $ 106,765,625   $
43,234,375 UBS Loan Finance LLC   $ 106,765,625   $ 43,234,375 Deutsche Bank AG,
New York Branch   $ 103,015,625   $ 41,984,375 Sumitomo Mitsui Banking
Corporation   $ 99,265,625   $ 40,734,375 The Bank of Nova Scotia, New York
Agency   $ 95,515,625   $ 39,484,375 The Royal Bank of Scotland plc   $
92,265,625   $ 37,734,375 Wachovia Bank, National Association   $ 92,265,625   $
37,734,375 Credit Suisse, Cayman Islands Branch   $ 88,515,625   $ 36,484,375
Merrill Lynch Bank USA   $ 88,515,625   $ 36,484,375 Morgan Stanley Bank   $
88,515,625   $ 36,484,375 U.S. Bank National Association   $ 88,515,625   $
36,484,375 Calyon New York Branch   $ 84,765,625   $ 35,234,375 PNC Bank,
National Association   $ 77,265,625   $ 32,734,375 Eurohypo AG, New York Branch
  $ 66,015,625   $ 28,984,375 National City Bank of Indiana   $ 75,000,000   $
25,000,000 Suntrust Bank   $ 60,000,000   $ 20,000,000 Bayerische Landesbank,
New York Branch   $ 56,250,000   $ 18,750,000 ING Real Estate Finance (USA) LLC
  $ 56,250,000   $ 18,750,000 LaSalle Bank National Association   $ 56,250,000  
$ 18,750,000 Landesbank Baden-Wurttemberg New York Branch   $ 48,750,000   $
16,250,000 Bank of Tokyo-.Mitsubishi UFJ, Ltd.    $ 45,000,000   $ 15,000,000
Fifth Third Bank   $ 45,000,000   $ 15,000,000 KBCBank N.V.    $ 45,000,000   $
15,000,000 Union Bank of California, N.A.    $ 45,000,000   $ 15,000,000 Hypo
Real Estate Capital Corporation   $ 37,500,000   $ 12,500,000 Mizuho Corporate
Bank, Ltd.    $ 37,500,000   $ 12,500,000 Nomura Funding Facility
Corporation Ltd.    $ 37,500,000   $ 12,500,000 Societe Generale   $ 37,500,000
  $ 12,500,000 C.M. Life Insurance Company   $ 3,000,000   $ 0 Massachusetts
Mutual Life Insurance Company   $ 47,000,000   $ 0 Emigrant Bank   $ 50,000,000
  $ 0 Westdeutsche Immobilienbank   $ 50,000,000   $ 0 Norddeutsche Landesbank
Girozentrale New York Branch   $ 30,000,000   $ 10,000,000 Aareal Bank AG   $
22,500,000   $ 7,500,000 Goldman Sachs Bank USA   $ 22,500,000   $ 7,500,000
Banco Popular de Puerto Rico   $ 25,000,000   $ 0 Bank of China   $ 25,000,000  
$ 0 Chang Hwa Commercial Bank, Ltd., New York Branch   $ 25,000,000   $ 0
Comerica Bank   $ 25,000,000   $ 0 Malayan Banking Berhad   $ 25,000,000   $ 0
People's United Bank   $ 25,000,000   $ 0 The Governor and Company of the Bank
of Ireland   $ 25,000,000   $ 0 Mega International Commercial Bank, New York
Branch   $ 15,000,000   $ 5,000,000 First Commercial Bank, Los Angeles Branch  
$ 20,000,000   $ 0 The Norinchukin Bank, New York Branch   $ 15,000,000   $
5,000,000 Bank of Taiwan, New York Agency   $ 15,000,000   $ 0 Chinatrust
Commercial Bank, New York Branch   $ 10,000,000   $ 0 Hua Nan Commercial
Bank Ltd., New York Agency   $ 10,000,000   $ 0    

--------------------------------------------------------------------------------

 

--------------------------------------------------------------------------------

TOTAL   $ 2,625,000,000   $ 875,000,000    

--------------------------------------------------------------------------------

 

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

QuickLinks

Exhibit 10.3