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Exhibit 10.1.9

TENTH
AMENDMENT
TO
AMENDED AND RESTATED
LIMITED PARTNERSHIP AGREEMENT
OF
THE MACERICH PARTNERSHIP, L.P.

Dated as of October 26, 2006

        THIS TENTH AMENDMENT (the "Amendment") TO THE AMENDED AND RESTATED
LIMITED PARTNERSHIP AGREEMENT DATED AS OF MARCH 16, 1994, AMENDED AS OF AUGUST
14, 1995, FURTHER AMENDED AS OF JUNE 27, 1997, FURTHER AMENDED AS OF NOVEMBER
16, 1997, FURTHER AMENDED AS OF FEBRUARY 25, 1998, FURTHER AMENDED AS OF
FEBRUARY 26, 1998, FURTHER AMENDED AS OF JUNE 17, 1998, FURTHER AMENDED AS OF
DECEMBER 23, 1998, FURTHER AMENDED AS OF NOVEMBER 9, 2000, AND FURTHER AMENDED
AS OF JULY 26, 2002 (the "Agreement") OF THE MACERICH PARTNERSHIP, L.P. (the
"Partnership"), dated as of October 26, 2006, is hereby adopted by The Macerich
Company, a Maryland corporation (the "Company"), as the general partner of The
Macerich Partnership, L.P., a Delaware limited partnership. For ease of
reference, capitalized terms used herein and not otherwise defined have the
meanings assigned to them in the Agreement.

        WHEREAS, the General Partner desires to establish and set forth the
terms of a new class of Partnership Interests designated as LTIP Units;

        WHEREAS, the LTIP Units shall have the terms set forth in Exhibit B to
this Amendment;

        WHEREAS, Section 3.3(a)(i) of the Agreement authorizes the General
Partner to cause the Partnership to issue additional interests in the
Partnership in one or more classes, or one or more series of any of such
classes, with such designations, preferences and relative, participating,
optional or other special rights, powers and duties, including rights, powers
and duties senior to those of the Limited Partners, all as shall be determined
by the General Partner in its sole and absolute discretion and without the
approval of any of the Limited Partners;

        WHEREAS, Section 12.1(b)(iii) of the Agreement provides that the General
Partner has the power, without the consent of the Limited Partners of the
Partnership, to amend the Agreement as may be required to facilitate or
implement setting forth the designations, rights, powers, duties, and
preferences of the holders of any additional interests in the Partnership issued
pursuant to Section 3.3; and

        WHEREAS, the General Partner has made the determination pursuant to
Section 12.1(b)(iii) of the Agreement that consent of the Limited Partners of
the Partnership is not required with respect to the matters set forth in this
Amendment.

        NOW, THEREFORE, the General Partner hereby amends the Agreement as
follows:

        1.     Section 2.2 of the Agreement is hereby supplemented by adding the
following paragraphs (f), (g) and (h) to the end thereof:

        (f)    Reserved.

        (g)   Reserved.

        (h)   Issuance of LTIP Units. From and after the date hereof the
Partnership shall be authorized to issue LTIP Units. From time to time the
General Partner may issue LTIP Units to Persons providing services to or for the
benefit of the Partnership. LTIP Units are intended to

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qualify as profits interests in the Partnership. LTIP Units shall have the terms
set forth in Exhibit B to the Tenth Amendment to this Agreement.

        2.     New Section 4.1A of the Agreement is hereby added to read as
follows:

        For purposes of the foregoing calculations of Section 4.1, issued and
outstanding LTIP Units with an associated LTIP Unit Distribution Participation
Date that falls on or before the Partnership Record Date for a particular
distribution shall be treated as outstanding Common Units. LTIP Units for which
the LTIP Unit Distribution Participation Date has not occurred as of the
Partnership Record Date for a particular distribution shall not be entitled to
any of such distribution.

        3.     In making distributions pursuant to Section 4.1 of the Agreement
and allocations pursuant to Sections 2.1 and 2.2 of the Allocations Exhibit, the
General Partner of the Partnership shall take into account the provisions of
Exhibit B to the Tenth Amendment to this Agreement.

        4.     Section 5.5 of the Partnership Agreement is amended by
designating the existing text of Section 5.5 as Section 5.5(a), and by appending
the following new Section 5.5(b):

        (b)   To the extent provided for in Regulations, revenue rulings,
revenue procedures and/or other IRS guidance issued after the date hereof, the
Partnership is hereby authorized to, and at the direction of the General Partner
shall, elect a safe harbor under which the fair market value of any Partnership
Interests issued after the effective date of such Regulations (or other
guidance) will be treated as equal to the liquidation value of such Partnership
Interests (i.e., a value equal to the total amount that would be distributed
with respect to such interests if the Partnership sold all of its assets for
their fair market value immediately after the issuance of such Partnership
Interests, satisfied its liabilities (excluding any non-recourse liabilities to
the extent the balance of such liabilities exceed the fair market value of the
assets that secure them) and distributed the net proceeds to the Partners under
the terms of this Agreement). In the event that the Partnership makes a safe
harbor election as described in the preceding sentence, each Partner hereby
agrees to comply with all safe harbor requirements with respect to transfers of
such Partnership Interests while the safe harbor election remains effective.

        5.     Article IX of the Agreement is hereby supplemented by adding the
following paragraphs (f), (g), (h) and (i) at the end of Section 9.1 thereof:

        (f)    Reserved.

        (g)   Reserved.

        (h)   Reserved.

        (i)    Holders of LTIP Units shall not be entitled to the Redemption
Rights provided for in Section 9.1 of this Agreement, unless and until such LTIP
Units have been converted into Common Units (or any other class or series of
Partnership Units entitled to such Redemption Rights). Notwithstanding the
foregoing, and except as otherwise permitted by the award, plan or other
agreement pursuant to which an LTIP Unit was issued, the Redemption Rights shall
not be exercisable with respect to any Common Unit issued upon conversion of an
LTIP Unit until two years after the date on which the LTIP Unit was issued,
provided however, that the foregoing restriction shall not apply if the right of
Redemption is exercised by an LTIP Unit holder in connection with a transaction
that falls within the definition of a "change of control" under the agreement or
agreements pursuant to which the LTIP Units were issued to such holder.

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        6.     The following definitions contained in the Glossary of Defined
Terms of the Agreement are amended as follows:

        (a)   The definition of the term "Common Unit" contained in the Glossary
of Defined Terms of the Agreement is hereby amended and restated in its entirety
as follows:

"Common Unit" shall mean Partnership Interests other than Preferred Units,
Series A Preferred Units, Series B Preferred Units, Series D Preferred Units,
Series N Preferred Units, Series P Preferred Units and LTIP Units.

        (b)   The definition of the term "Partnership Interest" contained in the
Glossary of Defined Terms of the Agreement is hereby amended and restated in its
entirety as follows:

"Partnership Interest" shall mean an ownership interest of a Partner in the
Partnership from time to time, including, as applicable, such Partner's Common
Units, Preferred Units, Series A Preferred Units, Series B Preferred Units,
Series D Preferred Units, Series N Preferred Units, Series P Preferred Units,
LTIP Units and Percentage Interest and such Partner's Capital Account, and any
and all other benefits to which the holder of such Partnership Interest may be
entitled as provided in this Agreement, together with all obligations of such
Person to comply with the terms of this Agreement.

        (c)   The definition of the term "Partnership Unit" contained in the
Glossary of Defined Terms of the Agreement is hereby amended and restated in its
entirety as follows:

"Partnership Unit" shall mean a Common Unit, Preferred Unit, Series A Preferred
Unit, Series B Preferred Unit, Series D Preferred Unit, Series N Preferred Unit,
Series P Preferred Unit or LTIP Unit and shall constitute a fractional,
undivided share of the Partnership Interests corresponding to that particular
class of Units.

        (d)   The definition of the term "Percentage Interest" contained in the
Glossary of Defined Terms of the Agreement is hereby amended and restated in its
entirety as follows:

"Percentage Interest" shall mean, with respect to any Partner, the percentage
ownership interest of such Partner in the Partnership from time to time,
represented by a fraction (expressed as a percentage), the numerator of which is
the number of Partnership Units then owned by such Partner, and the denominator
of which is the total number of Partnership Units then owned by all of the
Partners. For purposes of calculations of Percentage Interests at any time, the
Percentage Interest of any LTIP Unit Limited Partner and the total number of
Partnership Units shall exclude any LTIP Units for which the LTIP Unit
Distribution Participation Date has not occurred as of such time.

        7.     The Glossary of Defined Terms of the Agreement is amended by
inserting the following definitions in alphabetical order:

"2006 LTIP Plan" has the meaning set forth in Section 3.B of Exhibit B to the
Tenth Amendment to this Agreement.

"Book-Up Target" has the meaning set forth in Section 3.10 of the Allocations
Exhibit.

"Common Unit Economic Balance" has the meaning set forth in Section 3.10 of the
Allocations Exhibit.

"Constituent Person" has the meaning set forth in Section 7.G of Exhibit B to
the Tenth Amendment to this Agreement.

"Economic Capital Account Balance" has the meaning set forth in Section 3.10 of
the Allocations Exhibit.

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"Ineligible Unit" has the meaning set forth in Section 3.10 of the Allocations
Exhibit.

"Liquidating Gains" has the meaning set forth in Section 3.10 of the Allocations
Exhibit.

"Liquidating Losses" has the meaning set forth in Section 3.10 of the
Allocations Exhibit.

"LTIP Unit Adjustment Events" has the meaning set forth in Section 5 of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Conversion Date" has the meaning set forth in Section 7.C of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Conversion Notice" has the meaning set forth in Section 7.C of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Conversion Right" has the meaning set forth in Section 7.A of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Distribution Participation Date" has the meaning set forth in
Section 3.B of Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Distribution Payment Date" has the meaning set forth in Section 3.A
of Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Forced Conversion" has the meaning set forth in Section 7.D of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Forced Conversion Notice" has the meaning set forth in Section 7.D of
Exhibit B to the Tenth Amendment to this Agreement.

"LTIP Unit Limited Partner" means any Person holding LTIP Units, and named as a
LTIP Unit Limited Partner in Exhibit A attached hereto, as such Exhibit or the
Partnership's records may be amended from time to time.

"LTIP Units" means the Partnership Units designated as such having the rights,
powers, privileges, restrictions, qualifications and limitations set forth in
Exhibit B to the Tenth Amendment to this Agreement.

"Partnership Record Date" means the record date established by the General
Partner for the distribution of cash pursuant to Section 4.1 hereof, which
record date shall be the same as the record date established by the General
Partner for the payment of dividends to holders of Common Stock of the General
Partner on account of some or all of the General Partner's share of such
distribution by the Partnership.

"Series N Preferred Units" shall mean Partnership Units so designated by the
General Partner and reserved for future issuance in connection with the
partnership units of MACWH, L.P.

"Series P Preferred Units" shall mean Partnership Units so designated by the
General Partner and reserved for future issuance in connection with the
partnership units of MACWH, L.P.

"Target Balance" has the meaning set forth in Section 3.10 of the Allocations
Exhibit.

"Transaction" has the meaning set forth in Section 7.G of Exhibit B to the Tenth
Amendment to this Agreement.

"Unvested LTIP Units" has the meaning set forth in Section 2.A of Exhibit B to
the Tenth Amendment to this Agreement.

"Vested LTIP Units" has the meaning set forth in Section 2.A of Exhibit B to the
Tenth Amendment to this Agreement.

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"Vesting Agreement" has the meaning set forth in Section 2.A of Exhibit B to the
Tenth Amendment to this Agreement.

        8.     The term "Profit or Losses" contained in the Allocations Exhibit
is hereby amended to read "Net Income or Net Losses" in each place it is
located.

        9.     Section 1.3(b) of the Allocations Exhibit is hereby amended and
restated in its entirety as follows:

        (b)   Immediately prior to the times listed below, the Gross Asset
Values of all Partnership assets shall be adjusted to equal their respective
gross fair market values, as determined by the General Partner using such
reasonable method of valuation as it may adopt:

          (i)  the acquisition of an additional interest in the Partnership by
any new or existing Partner in exchange for more than a de minimis Capital
Contribution;

         (ii)  the acquisition of a more than de minimis additional interest in
the Partnership by any new or existing Partner as consideration for the
provision of services to or for the benefit of the Partnership in a partner
capacity or in anticipation of becoming a partner; provided, however, at the
time of grant of any LTIP Unit, the Gross Asset Values of all Partnership assets
shall be adjusted pursuant to this Section 1.3(b);

        (iii)  the distribution by the Partnership to a Partner of more than a
de minimis amount of property as consideration for an interest in the
Partnership; and

        (iv)  the liquidation of the Partnership within the meaning of
Regulations Section 1.704-1(b)(2)(ii)(g);

provided however that adjustments pursuant to clauses (i), (ii) and (iii) above
shall be made only if the General Partner determines that such adjustments are
necessary or appropriate to reflect the relative economic interests of the
Partners in the Partnership.

        10.   Section 2.1A is added to the Allocations Exhibit as follows:

        For purposes of determining allocations of Net Income pursuant to
Section 2.1, to the extent that the LTIP Unit Distribution Participation Date
with respect to an LTIP Unit has occurred, such LTIP Unit shall be treated as a
Common Unit.

        11.   Section 2.2A is added to the Allocations Exhibit as follows:

        For purposes of determining allocations of Net Loss pursuant to
Section 2.2, to the extent that the LTIP Unit Distribution Participation Date
with respect to an LTIP Unit has occurred, such LTIP Unit shall be treated as a
Common Unit.

        12.   Section 3 of the Allocations Exhibit is hereby supplemented by
appending the following new Section 3.9:

        3.9   Forfeiture Allocations. Upon a forfeiture of any unvested
Partnership Interest by any Partner, gross items of income, gain, loss or
deduction shall be allocated to such Partner if and to the extent required by
final Regulations promulgated after the effective date of the Tenth Amendment to
this Agreement to ensure that allocations made with respect to all unvested
Partnership Interests are recognized under Code Section 704(b).

        13.   Section 3 of the Allocations Exhibit is hereby supplemented by
adding the following new Sections 3.10 and 3.11 to the end thereof:

        3.10   Special Allocations With Respect to LTIP Units.

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        (a)   After giving effect to the special allocations set forth in
Sections 3.1 through 3.9 hereof, and the allocations of Net Income (including,
for the avoidance of doubt, Liquidating Gains that are a component of Net
Income) under Subsections 2.1(a) through (e) above, but before allocations of
Net Income are made under Section 2.1(f) above, any remaining Liquidating Gains
shall first be allocated to the holders of LTIP Units until the Economic Capital
Account Balances of such holders, to the extent attributable to their ownership
of LTIP Units, are equal to (i) the Common Unit Economic Balance, multiplied by
(ii) the number of their LTIP Units (with respect to each holder, the "Target
Balance"); provided, however, that no such Liquidating Gains will be allocated
with respect to any particular LTIP Unit (each, an "Ineligible Unit") if
cumulative Liquidating Losses of the Partnership have exceeded cumulative
Liquidating Gains of the Partnership during the period from the issuance of such
LTIP Unit through the date of such allocation. If, notwithstanding the
foregoing, not all LTIP Units (including Ineligible Units) are fully booked up,
Liquidating Gains shall be allocated among LTIP Units in a manner reasonably
determined by the General Partner. For the avoidance of doubt, Liquidating Gains
allocated with respect to an LTIP Unit pursuant to this Section 3.10(a) shall
reduce (but not below zero) the Book-Up Target for such LTIP Unit.

        (b)   After giving effect to the special allocations set forth in
Sections 3.1 through 3.9 hereof, and notwithstanding the provisions of Sections
2.1 and 2.2 above, if, due to distributions with respect to Common Units in
which the LTIP Units do not participate, forfeitures or otherwise, the Economic
Capital Account Balance of any present or former holder of LTIP Units, to the
extent attributable to the holder's ownership of LTIP Units, exceeds the Target
Balance, then Liquidating Losses shall be allocated to such holder to eliminate
the disparity; provided, however, that if Liquidating Losses are insufficient to
completely eliminate all such disparities, such losses shall be allocated among
LTIP Units in a manner reasonably determined by the General Partner.

        (c)   A "Book-Up Target" shall be established for each LTIP Unit. The
initial amount of the Book-Up Target for such LTIP Unit shall be the Common Unit
Economic Balance as determined on the later of (i) the date such LTIP Unit was
granted or (ii) the LTIP Unit Distribution Participation Date. The Book-Up
Target shall be reduced (not to less than zero) by allocations of Liquidating
Gains pursuant to Section 3.10(a) and reallocations of Capital Account balances
pursuant to Section 3.11, as determined by the General Partner. Notwithstanding
the foregoing, the Book-Up Target for any LTIP Unit for which the Economic
Capital Account Balance attributable to such LTIP Unit has at any time reached
an amount equal to the Common Unit Economic Balance determined as of such time
shall be equal to zero.

        (d)   The parties agree that the intent of this Section 3.10 is, (i) to
the extent possible, to make the Capital Account balance associated with each
LTIP Unit economically equivalent to the Capital Account balance associated with
the General Partner's Common Units (on a per-unit basis), and (ii) to allow
conversion of an LTIP Unit (assuming prior vesting) when sufficient Liquidating
Gains have been allocated to such LTIP Unit pursuant to Section 3.10(a) so that
either its initial Book-Up Target has been reduced to zero or the parity
described in (i) above has been achieved. The General Partner shall be permitted
to interpret this Section 3.10 or to amend this Agreement to the extent
necessary and consistent with this intention.

        (e)   For purposes of this Allocations Exhibit, the following
definitions shall apply:

        "Liquidating Gains" means any net gain realized in connection with the
actual or hypothetical sale of all or substantially all of the assets of the
Partnership (including upon the occurrence of any event of liquidation of the
Partnership), including but not limited to net gain realized in

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connection with an adjustment to the Gross Asset Value of Partnership assets
under the definition of Gross Asset Value in Section 1.3 of the Allocations
Exhibit.

        "Liquidating Losses" means any net loss realized in connection with the
actual or hypothetical sale of all or substantially all of the assets of the
Partnership (including upon the occurrence of any event of liquidation of the
Partnership), including but not limited to net loss realized in connection with
an adjustment to the Gross Asset Value of Partnership assets under the
definition of Gross Asset Value in Section 1.3 of the Allocations Exhibit.

        "Economic Capital Account Balance" means, with respect to a holder of
LTIP Units, as of any date, its Capital Account balance, plus the amount of its
shares of any Minimum Gain Attributable to Partner Nonrecourse Debt or
Partnership Minimum Gain, in either case as of such date and only to the extent
attributable to its ownership of LTIP Units.

        "Common Unit Economic Balance" shall mean as of any date, (i) the
Capital Account balance of the General Partner, plus the amount of the General
Partner's share of any Minimum Gain Attributable to Partner Nonrecourse Debt or
Partnership Minimum Gain, in either case to the extent attributable to the
General Partner's ownership of Common Units and computed on a hypothetical basis
after taking into account all allocations through such date divided by (ii) the
number of the General Partner's Common Units as of such date.

        3.11   Special Forfeiture Reallocations. If, in connection with any
forfeiture of LTIP Units, the balance of the portion of the Capital Account of
the holder that is attributable to all of his or her LTIP Units exceeds the
Target Balance, such portion of such holder's Capital Account shall be reduced
to the Target Balance, and the Book-Up Target of all LTIP Units then held by
such holder shall be reduced to zero. Otherwise, the Capital Account of the
holder that is attributable to the forfeited LTIP Units shall be reallocated in
a manner reasonably determined by the General Partner.

        14.   Exhibits A, C and D, attached to this Amendment, are hereby made a
part of the Agreement.

        15.   Except as expressly amended hereby, the Agreement shall remain in
full force and effect.

        IN WITNESS WHEREOF, the General Partner has executed this Amendment as
of the date first written above.

  THE MACERICH COMPANY                           By: /s/ RICHARD A. BAYER

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    Name: Richard A. Bayer     Title: Executive Vice President, Chief
Legal Officer and Secretary

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Exhibit A
LTIP Units

As of October 26, 2006

LTIP Unit Limited Partner

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  LTIP Units

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Arthur M. Coppola   85,335 Edward C. Coppola   49,779 Richard A. Bayer   37,927
Thomas E. O' Hern   42,668

        Further issuances of LTIP Units will be kept in the records of the
Partnership.

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Exhibit B
LTIP Units

        The following are the terms of the LTIP Units:

        1.     Designation.    A class of Partnership Units in the Partnership
designated as the "LTIP Units" is hereby established. LTIP Units are intended to
qualify as profits interests in the Partnership. The number of LTIP Units that
may be issued shall not be limited.

        2.     Vesting.

        A.    Vesting, Generally.    LTIP Units may, in the sole discretion of
the General Partner, be issued subject to vesting, forfeiture and additional
restrictions on transfer pursuant to the terms of an award, vesting or other
similar agreement (a "Vesting Agreement"). The terms of any Vesting Agreement
may be modified by the General Partner from time to time in its sole discretion,
subject to any restrictions on amendment imposed by the relevant Vesting
Agreement or by the terms of any plan pursuant to which the LTIP Units are
issued, if applicable. LTIP Units that have vested and are no longer subject to
forfeiture under the terms of a Vesting Agreement are referred to as "Vested
LTIP Units"; all other LTIP Units are referred to as "Unvested LTIP Units."
Subject to the terms of any Vesting Agreement, a holder of LTIP Units shall be
entitled to transfer his or her LTIP Units to the same extent, and subject to
the same restrictions as holders of Common Units are entitled to transfer their
Common Units pursuant to Article VIII of the Agreement.

        B.    Forfeiture or Transfer of Unvested LTIP Units.    Unless otherwise
specified in the relevant Vesting Agreement, upon the occurrence of any event
specified in a Vesting Agreement as resulting in either the forfeiture of any
LTIP Units, or the repurchase by the Partnership or the General Partner of LTIP
Units at a specified purchase price, then upon the occurrence of the
circumstances resulting in such forfeiture or repurchase by the Partnership or
the General Partner, the relevant LTIP Units shall immediately, and without any
further action, be treated as cancelled and no longer outstanding for any
purpose, or as transferred to the Partnership or General Partner, as applicable.
Unless otherwise specified in the Vesting Agreement, no consideration or other
payment shall be due with respect to any LTIP Units that have been forfeited,
other than any distributions declared with a record date prior to the effective
date of the forfeiture. In connection with any forfeiture or repurchase of LTIP
Units, the balance of the portion of the Capital Account of the holder that is
attributable to all of his or her LTIP Units shall be reduced by the amount, if
any, by which it exceeds the target balance contemplated by Section 3.10 of the
Agreement, calculated with respect to the holder's remaining LTIP Units, if any.

        C.    Legend.    Any certificate evidencing an LTIP Unit shall bear an
appropriate legend indicating that additional terms, conditions and restrictions
on transfer, including without limitation any Vesting Agreement, apply to the
LTIP Unit.

        3.     Distributions.

        A.    LTIP Distribution Amount.    Commencing from and after the LTIP
Unit Distribution Participation Date established for any LTIP Units, such LTIP
Units shall be entitled to receive, if, when and as authorized by the General
Partner out of funds or other property legally available for the payment of
distributions, regular, special, extraordinary or other distributions (other
than distributions representing proceeds of a sale or other disposition of all
or substantially all of the assets of the Partnership) which may be made from
time to time, in an amount per unit equal to the amount of any such
distributions that would have been payable to such holders if the LTIP Units had
been Common Units (if specified in the Vesting Agreement or other documentation
pursuant to which the LTIP Units are issued). LTIP Units shall also be entitled
to receive, if, when and as authorized by the General Partner out of funds or
other property legally available for the payment of distributions, distributions
representing proceeds of a sale or other disposition of all or

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substantially all of the assets of the Partnership in an amount per unit equal
to the amount of any such distributions payable on the Common Units, whether
made prior to, on or after the LTIP Unit Distribution Participation Date,
provided that the amount of such distributions shall not exceed the positive
balances of the Capital Accounts of the holders of such LTIP Units to the extent
attributable to the ownership of such LTIP Units. Distributions on the LTIP
Units, if authorized, shall be payable on such dates and in such manner as may
be authorized by the General Partner (any such date, a "LTIP Unit Distribution
Payment Date"); provided that the LTIP Unit Distribution Payment Date shall be
the same as the corresponding date relating to the corresponding distribution on
the Common Units. The record date for determining which holders of LTIP Units
are entitled to receive a distribution shall be the Partnership Record Date for
that distribution. All distributions paid with respect to LTIP Units prior to
the date on which the determination is made with respect to events resulting in
the forfeiture of such LTIP Units or the repurchase by the Partnership or the
General Partner of such LTIP Units shall be retained by the holder of such LTIP
Units and not subject to forfeiture or restitution in the event that Unvested
LTIP Units fail to become Vested LTIP Units. Following such date of
determination, no further distributions will be paid with respect to Unvested
LTIP Units that have been forfeited or are repurchased by the Partnership or the
General Partner, other than any distributions declared with a record date prior
to the effective date of the forfeiture or repurchase.

        B.    LTIP Unit Distribution Participation Date.    The "LTIP Unit
Distribution Participation Date" for each LTIP Unit will be (i) with respect to
LTIP Units granted pursuant to The Macerich Company 2006 Long-Term Incentive
Plan (the "2006 LTIP Plan"), the Effective Date (as defined in the Vesting
Agreement of each Person granted LTIP Units under the 2006 LTIP Plan) or
(ii) with respect to other LTIP Units, such date as may be specified in the
Vesting Agreement or other documentation pursuant to which such LTIP Units are
issued.

        4.     Allocations.

        Commencing with the portion of the taxable year of the Partnership that
begins on the LTIP Unit Distribution Participation Date established for any LTIP
Units, such LTIP Units shall be allocated Net Income and Net Loss in amounts per
LTIP Unit equal to the amounts allocated per Common Unit. The allocations
provided by the preceding sentence shall be subject to Sections 2.1 and 2.2 and
in addition to any special allocations required by Sections 3.1 through 3.11,
each as provided in the Allocations Exhibit. The General Partner is authorized
in its discretion to adjust the allocations made under this Section 4 after the
LTIP Unit Distribution Participation Date, so that the ratio of (i) the total
amount of Net Income or Net Loss allocated with respect to each LTIP Unit in the
taxable year in which that LTIP Unit's LTIP Unit Distribution Participation Date
falls (excluding special allocations under Section 3.10 and Section 3.11 of the
Allocations Exhibit), to (ii) the total amount distributed to that LTIP Unit
with respect to such period, is more nearly equal to the ratio of (i) the Net
Income and Net Loss allocated with respect to the General Partner's Common Units
in such taxable year to (ii) the amounts distributed to the General Partner with
respect to such Common Units and such taxable year.

        5.     Adjustments.

        The Partnership shall maintain at all times a one-to-one correspondence
between LTIP Units and Common Units for conversion, distribution and other
purposes, including without limitation complying with the following procedures;
provided that the foregoing is not intended to alter the special allocations
pursuant to Sections 3.9, 3.10 and 3.11 of the Allocations Exhibit, differences
between distributions (other than, with respect to LTIP Units having an LTIP
Unit Distribution Participation Date determined under Section 3.B(ii) above,
distributions representing proceeds of a sale or other disposition of all or
substantially all of the assets of the Partnership) to be made with respect to
the LTIP Units and Common Units prior to the LTIP Unit Distribution
Participation Date for such LTIP Units, differences between distributions (other
than, with respect to LTIP Units having an LTIP Unit

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Distribution Participation Date determined under Section 3.B(ii) above,
distributions representing proceeds of a sale or other disposition of all or
substantially all of the assets of the Partnership) to be made with respect to
the LTIP Units and Common Units pursuant to Section 10.2 of the Agreement or
Section 3.A hereof in the event that the Capital Accounts attributable to the
LTIP Units are less than those attributable to the Common Units due to
insufficient special allocations pursuant to Section 3.10 and 3.11 of the
Allocations Exhibit or related provisions. If an LTIP Unit Adjustment Event (as
defined below) occurs, then the General Partner shall make a corresponding
adjustment to the LTIP Units to maintain such one-for-one correspondence between
Common Units and LTIP Units. The following shall be "LTIP Unit Adjustment
Events": (A) the Partnership makes a distribution on all outstanding Common
Units in Partnership Units, (B) the Partnership subdivides the outstanding
Common Units into a greater number of units or combines the outstanding Common
Units into a smaller number of units, or (C) the Partnership issues any
Partnership Units in exchange for its outstanding Common Units by way of a
reclassification or recapitalization of its Common Units. If more than one LTIP
Unit Adjustment Event occurs, the adjustment to the LTIP Units need be made only
once using a single formula that takes into account each and every LTIP Unit
Adjustment Event as if all LTIP Unit Adjustment Events occurred simultaneously.
For the avoidance of doubt, the following shall not be LTIP Unit Adjustment
Events: (x) the issuance of Partnership Units in a financing, reorganization,
acquisition or other similar business transaction, (y) the issuance of
Partnership Units pursuant to any employee benefit or compensation plan or
distribution reinvestment plan, or (z) the issuance of any Partnership Units to
the General Partner in respect of a Capital Contribution to the Partnership of
proceeds from the sale of securities by the General Partner. If the Partnership
takes an action affecting the Common Units other than actions specifically
described above as LTIP Unit Adjustment Events and in the opinion of the General
Partner such action would require an adjustment to the LTIP Units to maintain
the one-to-one correspondence described above, the General Partner shall make
such adjustment to the LTIP Units, to the extent permitted by law and by the
terms of any plan pursuant to which the LTIP Units have been issued, in such
manner and at such time as the General Partner, in its sole discretion, may
determine to be appropriate under the circumstances. If an adjustment is made to
the LTIP Units as herein provided, the Partnership shall promptly file in the
books and records of the Partnership an officer's certificate setting forth such
adjustment and a brief statement of the facts requiring such adjustment, which
certificate shall be conclusive evidence of the correctness of such adjustment
absent manifest error. Promptly after filing of such certificate, the
Partnership shall mail a notice to each holder of LTIP Units setting forth the
adjustment to his or her LTIP Units and the effective date of such adjustment.

        6.     Ranking.

        The LTIP Units shall rank on parity with the Common Units in all
respects and junior to all Preferred Units, Series A Preferred Units, Series B
Preferred Units, Series D Preferred Units, Series N Preferred Units, and
Series P Preferred Units, with respect to distribution rights and rights upon
voluntary or involuntary liquidation, winding up or dissolution of the
Partnership, subject to the proviso in the first sentence of Section 5.

        7.     Right to Convert LTIP Units into Common Units.

        A.    Conversion Right.    A holder of LTIP Units shall have the right
(the "LTIP Unit Conversion Right"), at his or her option, at any time to convert
all or a portion of his or her Vested LTIP Units the Book-Up Target of which is
zero into Common Units. Holders of LTIP Units shall not have the right to
convert Unvested LTIP Units into Common Units until they become Vested LTIP
Units; provided, however, that when a holder of LTIP Units is notified of the
expected occurrence of an event that will cause his or her Unvested LTIP Units
to become Vested LTIP Units, such Person may give the Partnership an LTIP Unit
Conversion Notice conditioned upon and effective as of the time of vesting, and
such LTIP Unit Conversion Notice, unless subsequently revoked by the holder of
the LTIP Units, shall be accepted by the Partnership subject

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to such condition. The General Partner shall have the right at any time to cause
a conversion of Vested LTIP Units the Book-up Target of which is zero into
Common Units. In all cases, the conversion of any LTIP Units into Common Units
shall be subject to the conditions and procedures set forth in this Section 7.

        B.    Number of Units Convertible.    A holder of Vested LTIP Units may
convert such Vested LTIP Units the Book-Up Target of which is zero into an equal
number of fully paid and non-assessable Common Units, giving effect to all
adjustments (if any) made pursuant to Section 5.

        C.    Notice.    In order to exercise his or her Conversion Right, a
holder of LTIP Units shall deliver a notice (a "LTIP Unit Conversion Notice") in
the form attached as Exhibit C to this Amendment not less than 10 nor more than
60 days prior to a date (the "LTIP Unit Conversion Date") specified in such LTIP
Unit Conversion Notice. Each holder of LTIP Units covenants and agrees with the
Partnership that all Vested LTIP Units to be converted pursuant to this
Section 7 shall be free and clear of all liens. Notwithstanding anything herein
to the contrary (but subject to Section 9.1 of the Agreement and the Redemption
Rights Exhibit to the Agreement), a holder of LTIP Units may deliver an Exercise
Notice pursuant to Section 9.1 of the Agreement and the Redemption Rights
Exhibit to the Agreement relating to those Common Units that will be issued to
such holder upon conversion of such LTIP Units into Common Units in advance of
the LTIP Unit Conversion Date; provided, however, that the redemption of such
Common Units by the Partnership shall in no event take place until the LTIP Unit
Conversion Date. For clarity, it is noted that the objective of this paragraph
is to put a holder of LTIP Units in a position where, if he or she so wishes,
the Common Units into which his or her Vested LTIP Units will be converted can
be redeemed by the Partnership simultaneously with such conversion, with the
further consequence that, if the General Partner elects to assume the
Partnership's redemption obligation with respect to such Common Units under
Section 9.1 of the Agreement and the Redemption Rights Exhibit to the Agreement
by delivering to such holder Shares rather than cash, then such holder can have
such Shares issued to him or her simultaneously with the conversion of his or
her Vested LTIP Units the Book-Up Target of which is zero into Common Units. The
General Partner shall cooperate with a holder of LTIP Units to coordinate the
timing of the different events described in the foregoing sentence.

        D.    Forced Conversion.    The Partnership, at any time at the election
of the General Partner, may cause any number of Vested LTIP Units the Book-Up
Target of which is zero held by a holder of LTIP Units to be converted (a "LTIP
Unit Forced Conversion") into an equal number of Common Units, giving effect to
all adjustments (if any) made pursuant to Section 5. In order to exercise its
right to cause an LTIP Unit Forced Conversion, the Partnership shall deliver a
notice (a "LTIP Unit Forced Conversion Notice") in the form attached as
Exhibit D to the Amendment to the applicable holder not less than 10 nor more
than 60 days prior to the LTIP Unit Conversion Date specified in such LTIP Unit
Forced Conversion Notice. A Forced LTIP Unit Conversion Notice shall be provided
in the manner provided in Section 13.1 of the Agreement.

        E.    Conversion Procedures.    Subject to any redemption of Common
Units to be received upon the conversion of Vested LTIP Units, a conversion of
Vested LTIP Units for which the holder thereof has given an LTIP Unit Conversion
Notice or the Partnership has given a Forced LTIP Unit Conversion Notice shall
occur automatically after the close of business on the applicable LTIP Unit
Conversion Date without any action on the part of such holder of LTIP Units, as
of which time such holder of LTIP Units shall be credited on the books and
records of the Partnership with the issuance as of the opening of business on
the next day of the number of Common Units issuable upon such conversion. After
the conversion of LTIP Units as aforesaid, the Partnership shall deliver to such
holder of LTIP Units, upon his or her written request, a certificate of the
General Partner certifying the number of Common Units and remaining LTIP Units,
if any, held by such Person immediately after such conversion.

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        F.     Treatment of Capital Account.    For purposes of making future
allocations under Section 3.10 of the Allocations Exhibit, the portion of the
Economic Capital Account Balance of the applicable holder of LTIP Units that is
treated as attributable to his or her LTIP Units shall be reduced in accordance
with the Economic Capital Account Balance of such holder attributable to the
LTIP Units converted.

        G.    Mandatory Conversion in Connection with a Transaction.    If the
Partnership or the General Partner shall be a party to any transaction
(including without limitation a merger, consolidation, unit exchange, self
tender offer for all or substantially all Common Units or other business
combination or reorganization, or sale of all or substantially all of the
Partnership's assets, but excluding any transaction which constitutes an LTIP
Unit Adjustment Event), in each case as a result of which Common Units shall be
exchanged for or converted into the right, or the holders of Common Units shall
otherwise be entitled, to receive cash, securities or other property or any
combination thereof (each of the foregoing being referred to herein as a
"Transaction"), then the General Partner shall, immediately prior to the
Transaction, exercise its right to cause a LTIP Unit Forced Conversion with
respect to the maximum number of LTIP Units then eligible for conversion, taking
into account any allocations that occur in connection with the Transaction or
that would occur in connection with the Transaction if the assets of the
Partnership were sold at the Transaction price or, if applicable, at a value
determined by the General Partner in good faith using the value attributed to
the Partnership Units in the context of the Transaction (in which case the LTIP
Unit Conversion Date shall be the effective date of the Transaction and the
conversion shall occur immediately prior to the effectiveness of the
Transaction).

        In anticipation of such LTIP Unit Forced Conversion and the consummation
of the Transaction, the Partnership shall use commercially reasonable efforts to
cause each holder of LTIP Units to be afforded the right to receive in
connection with such Transaction in consideration for the Common Units into
which his or her LTIP Units will be converted the same kind and amount of cash,
securities and other property (or any combination thereof) receivable upon the
consummation of such Transaction by a holder of the same number of Common Units,
assuming such holder of Common Units is not a Person with which the Partnership
consolidated or into which the Partnership merged or which merged into the
Partnership or to which such sale or transfer was made, as the case may be (a
"Constituent Person"), or an Affiliate of a Constituent Person. In the event
that holders of Common Units have the opportunity to elect the form or type of
consideration to be received upon consummation of the Transaction, prior to such
Transaction the General Partner shall give prompt written notice to each holder
of LTIP Units of such election, and shall use commercially reasonable efforts to
afford such holders the right to elect, by written notice to the General
Partner, the form or type of consideration to be received upon conversion of
each LTIP Unit held by such holder into Common Units in connection with such
Transaction. If a holder of LTIP Units fails to make such an election, such
holder (and any of its transferees) shall receive upon conversion of each LTIP
Unit held by him or her (or by any of his or her transferees) the same kind and
amount of consideration that a holder of a Common Unit would receive if such
holder of Common Units failed to make such an election.

        Subject to the rights of the Partnership and the General Partner under
any Vesting Agreement and the terms of any plan under which LTIP Units are
issued, the Partnership shall use commercially reasonable efforts to cause the
terms of any Transaction to be consistent with the provisions of this Section 7
and to enter into an agreement with the successor or purchasing entity, as the
case may be, for the benefit of any holders of LTIP Units whose LTIP Units will
not be converted into Common Units in connection with the Transaction that will
(i) contain provisions enabling the holders of LTIP Units that remain
outstanding after such Transaction to convert their LTIP Units into securities
as comparable as reasonably possible under the circumstances to the Common Units
and (ii) preserve as

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far as reasonably possible under the circumstances the distribution, special
allocation, conversion, and other rights set forth in the Agreement for the
benefit of the holders of LTIP Units.

        8.     Redemption at the Option of the Partnership.

        LTIP Units will not be redeemable at the option of the Partnership;
provided, however, that the foregoing shall not prohibit the Partnership from
(i) repurchasing LTIP Units from the holder thereof if and to the extent such
holder agrees to sell such LTIP Units or (ii) from exercising its LTIP Unit
Forced Conversion right.

        9.     Voting Rights.

        A.    Voting with Common Units.    Holders of LTIP Units shall have the
right to vote on all matters submitted to a vote of the holders of Common Units;
holders of LTIP Units and Common Units shall vote together as a single class,
together with any other class or series of Partnership Units upon which like
voting rights have been conferred. In any matter in which the LTIP Units are
entitled to vote, including an action by written consent, each LTIP Unit shall
be entitled to vote a Percentage Interest equal on a per unit basis to the
Percentage Interest represented by each Common Unit.

        B.    Special Approval Rights.    Except as provided in Section 9.A.
above, holders of LTIP Units shall only (a) have those voting rights required
from time to time by non-waivable provisions of applicable law, if any, and
(b) have the additional voting rights that are expressly set forth in this
Section 9.B. The General Partner and/or the Partnership shall not, without the
affirmative vote of holders of more than 50% of the then outstanding LTIP Units
affected thereby, given in person or by proxy, either in writing or at a meeting
(voting separately as a class), take any action that would materially and
adversely alter, change, modify or amend, whether by merger, consolidation or
otherwise, the rights, powers or privileges of such LTIP Units, subject to the
following exceptions:

          (i)  no separate consent of the holders of LTIP Units will be required
if and to the extent that any such alteration, change, modification or amendment
would equally, ratably and proportionately alter, change, modify or amend the
rights, powers or privileges of the Common Units (in which event the holders of
LTIP Units shall only have such voting rights, if any, as provided in Sections
6.3, 7.1, 10.1(b), Article XII of the Agreement, or otherwise as expressly
provided for in the Agreement, in accordance with Section 9.A above);

         (ii)  with respect to any merger, consolidation or other business
combination or reorganization, so long as either (w) the LTIP Units are
converted into Common Units immediately prior to the effectiveness of the
transaction, (x) the holders of LTIP Units either will receive, or will have the
right to elect to receive, for each LTIP Unit an amount of cash, securities, or
other property equal to the greatest amount of cash, securities or other
property paid to a holder of one Common Unit in consideration of one Common Unit
pursuant to the terms of such transaction, (y) the LTIP Units remain outstanding
with the terms thereof materially unchanged, or (z) if the Partnership is not
the surviving entity in such transaction, the LTIP Units are exchanged for a
security of the surviving entity with terms that are materially the same with
respect to rights to allocations, distributions, redemption, conversion and
voting as the LTIP Units and without any income, gain or loss expected to be
recognized by the holder upon the exchange for federal income tax purposes (and
with the terms of the Common Units or such other securities into which the LTIP
Units (or the substitute security therefor) are convertible materially the same
with respect to rights to allocations, distributions, redemption, conversion and
voting), such merger, consolidation or other business combination or
reorganization shall not be deemed to materially and adversely alter, change,
modify or amend the rights, powers or privileges of the LTIP Units, provided
further, that if some, but not all, of the LTIP Units are converted into Common
Units immediately prior to the

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effectiveness of the transaction (and neither clause (y) or (z) above is
applicable), then the consent required pursuant to this Section will be the
consent of the holders of more than 50% of the LTIP Units to be outstanding
following such conversion;

        (iii)  any creation or issuance of Partnership Units (whether ranking
junior to, on a parity with or senior to the LTIP Units with respect to payment
of distributions, right of redemptions and the distribution of assets upon
liquidation, dissolution or winding up), which either (x) does not require the
consent of the holders of Common Units or (y) does require such consent and is
authorized by a vote of the holders of Common Units and LTIP Units voting
together as a single class pursuant to Section 9.A above, together with any
other class or series of units of limited partnership interest in the
Partnership upon which like voting rights have been conferred, shall not be
deemed to materially and adversely alter, change, modify or amend the rights,
powers or privileges of the LTIP Units; and

        (iv)  any waiver by the Partnership of restrictions or limitations
applicable to any outstanding LTIP Units with respect to any holder or holders
thereof shall not be deemed to materially and adversely alter, change, modify or
amend the rights, powers or privileges of the LTIP Units with respect to other
holders.

        The foregoing voting provisions will not apply if, as of or prior to the
time when the action with respect to which such vote would otherwise be required
will be taken or be effective, all outstanding LTIP Units shall have been
converted and/or redeemed, or provision is made for such redemption and/or
conversion to occur as of or prior to such time.

[End of text]

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EXHIBIT C

NOTICE OF ELECTION BY PARTNER TO CONVERT
LTIP UNITS INTO COMMON UNITS

        The undersigned holder of LTIP Units hereby irrevocably elects to
convert the number of Vested LTIP Units in The Macerich Partnership, L.P. (the
"Partnership") set forth below into Common Units in accordance with the terms of
the Amended and Restated Agreement of Limited Partnership of the Partnership, as
amended. The undersigned hereby represents, warrants, and certifies that the
undersigned: (a) has title to such LTIP Units, free and clear of the rights or
interests of any other person or entity other than the Partnership; (b) has the
full right, power, and authority to cause the conversion of such LTIP Units as
provided herein; and (c) has obtained the consent or approval of all persons or
entities, if any, having the right to consent or approve such conversion.

Name of Holder:     

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(Please Print: Exact Name as Registered with Partnership)

         Number of LTIP Units to be Converted:       

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       Conversion Date:     

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(Signature of Holder: Sign Exact Name as Registered with Partnership)         
           

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(Street Address)                     

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(City)                               (State)                               (Zip
Code)  

         Signature Guaranteed by:       

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EXHIBIT D

NOTICE OF ELECTION BY PARTNERSHIP TO FORCE CONVERSION
OF LTIP UNITS INTO COMMON UNITS

        The Macerich Partnership, L.P. (the "Partnership") hereby irrevocably
elects to cause the number of LTIP Units held by the holder of LTIP Units set
forth below to be converted into Common Units in accordance with the terms of
the Amended and Restated Limited Partnership Agreement of the Partnership, as
amended.

       Name of Holder:     

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(Please Print: Exact Name as Registered with Partnership)

       Number of LTIP Units to be Converted:     

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       Conversion Date:     

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QuickLinks

Exhibit 10.1.9

TENTH AMENDMENT TO AMENDED AND RESTATED LIMITED PARTNERSHIP AGREEMENT OF THE
MACERICH PARTNERSHIP, L.P.
Dated as of October 26, 2006
Exhibit A LTIP Units
As of October 26, 2006
Exhibit B LTIP Units
EXHIBIT C
NOTICE OF ELECTION BY PARTNER TO CONVERT LTIP UNITS INTO COMMON UNITS
EXHIBIT D
NOTICE OF ELECTION BY PARTNERSHIP TO FORCE CONVERSION OF LTIP UNITS INTO COMMON
UNITS