<PAGE>   1
                                                                   EXHIBIT 10.17


                              FOURTH AMENDMENT TO
                                LEASE AGREEMENT


       THIS FOURTH AMENDMENT TO LEASE AGREEMENT (this "AMENDMENT") is by and
between TRST IRVING, INC., a Texas corporation ("LANDLORD"), and I2
TECHNOLOGIES, INC., a Texas corporation ("TENANT").

                                    RECITALS

       A.     Landlord and Tenant have previously entered into a certain Lease
Agreement dated July 14, 1995 (the "ORIGINAL LEASE"), with respect to Suite No.
1600 in the office building located at 909 E. Las Colinas Boulevard, Irving,
Texas.  (Except as otherwise provided herein, all terms with initial capital
letters have the same meaning ascribed to them in the Original Lease.)

       B.     The Original Lease has been amended by (i) a certain First
Amendment to Lease Agreement dated February 6, 1996, whereby Landlord and
Tenant confirmed an increase in the Basic Rental, (ii) a certain Second
Amendment to Lease Agreement (the "SECOND AMENDMENT") dated February 23, 1996,
whereby Tenant increased the size of the Premises by leasing Suite No. 1400 in
the Building, and (iii) a certain Third Amendment to Lease Agreement (the
"THIRD AMENDMENT") dated July 25, 1996, whereby Tenant increased the size of
the Premises by leasing Suite No. 1300 in the Building.  (The Original Lease,
as amended, is hereinafter referred to as the "LEASE.")

       C.     Tenant desires to lease additional space (specifically, the
twelfth floor in the Building) from Landlord.

                                   AGREEMENTS

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

       1.     The Basic Lease Information, which sets forth various
definitions, is hereby amended as follows:

       a.     The definition of Premises is amended to read as follows:

              "Premises:    (i) Suite No. 1600 (the "Initial Lease Area"),
                            containing 36,534 rentable square feet, and (ii)
                            Suite No. 1400 containing 10,926 rentable square
                            feet, Suite No. 1300 containing 18,197 rentable
                            square feet, and Suite No. 1200 containing 18,583
                            rentable square feet (Suite Nos. 1400,





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                            1300, and 1200 are sometimes collectively referred
                            to as the "Additional Lease Area"), in the office
                            building known as Computer Associates Tower, 909 E.
                            Las Colinas Blvd. (the "Building") located in the
                            City of Irving, Dallas County, Texas, described on
                            Exhibit 'I'.  The Premises are outlined on the plan
                            attached to the Lease as Exhibit 'A'."

       b.     The definition of Term is amended to read as follows:

              "Term:        Commencing on the Commencement Date and ending on
                            October 31, 2000, subject to adjustment or earlier
                            termination as provided in the Lease.  As used
                            herein, the term 'Commencement Date' shall mean the
                            following:

                            (a)    with respect to the Initial Lease Area, the
                                   Commencement Date shall mean October 15,
                                   1995;

                            (b)    with respect to Suite No. 1400, the
                                   Commencement Date shall mean August 1, 1996;


                            (c)    with respect to Suite No. 1300, the
                                   Commencement Date shall mean October 1,
                                   1996; and

                            (d)    with respect to Suite No. 1200, the
                                   Commencement Date shall mean the earlier of
                                   (i) the date upon which Tenant commences
                                   business in Suite No. 1200, or (ii) April 1,
                                   1997."

       c.     The definition of Basic Rental is amended to read as follows:

              "Basic Rental:       Payable monthly based on the following
                                   annual amounts:  Subject to increase in
                                   accordance with Section 4 and Exhibit 'C' of
                                   the Lease, (i) the annual Basic Rental for
                                   the Initial Lease Area will be $15.94 per
                                   rentable square foot per year during the
                                   first twelve (12) month period (months 1-
                                   12), $15.94 per rentable square foot per
                                   year during the second twelve (12) month
                                   period (months 13-24), $16.44 per rentable
                                   square foot per year during the third twelve
                                   (12) month period (months 25-36), $16.94 per
                                   rentable square foot per year during the
                                   fourth twelve (12)





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<PAGE>   3
                                   month period (months 37-48), and $17.44 per
                                   rentable square foot per year during the
                                   last twelve (12) month period (months 49-
                                   60); (ii) the annual Basic Rental for Suite
                                   No. 1400 will be $20.00 per rentable square
                                   foot per year throughout the entire Term of
                                   Suite No. 1400; (iii) the annual Basic
                                   Rental for Suite No. 1300 will be $21.00 per
                                   rentable square foot per year throughout the
                                   entire Term of Suite No. 1300; and (iv) the
                                   annual Basic Rental for Suite No. 1200 will
                                   be $22.00 per rentable square foot per year
                                   throughout the entire Term of Suite No.
                                   1200."

       2.     Exhibit "A" attached to this Amendment is hereby substituted for
the Exhibit "A" attached to the Lease.

       3.     Tenant accepts Suite No. 1200 in its "as is" condition.  Landlord
and Tenant hereby agree that Suite No. 1200 will be completed in accordance
with Exhibit "B" attached hereto and incorporated herein for all purposes.

       4.     Landlord and Tenant confirm that Tenant is obligated under the
Lease to pay an amount per each rentable square foot in the Premises equal to
the Excess from time to time of the actual Basic Cost per rentable square foot
in the Building over the Expense Stop.  Landlord and Tenant agree that for
purposes of calculating the Excess with respect to Suite No. 1200, the Expense
Stop will be the actual Basic Cost per rentable square foot for calendar year
1997.  Landlord and Tenant confirm that the Expense Stop for the Initial Lease
Area and for Suite Nos. 1400 and 1300 is the actual Basic Costs per rentable
square foot for calendar year 1995.

       5.     Landlord and Tenant confirm that Tenant is entitled to use
certain parking spaces in the Parking Garage pursuant to, and in accordance
with, Exhibit "E" attached to the Lease, paragraph 4 of the Second Amendment,
and paragraph 4 of the Third Amendment.  In addition to such spaces, Tenant
will also be permitted to use sixty-six (66) undesignated vehicular parking
spaces in the Parking Garage during the initial Term of Suite No. 1200 (i.e.,
Tenant's rights to such additional parking spaces will not commence until the
Commencement Date of Suite No. 1200).  (Of the 66 parking spaces provided for
in this Amendment, approximately 26 will be underground, and approximately 40
will be above ground.)  Tenant may use such additional parking spaces at no
charge during the first 19 months of such Term, but Tenant will pay $40.00 per
space per month during the remainder of the Term of the Lease.  Tenant's use of
such parking spaces will be subject to such terms, conditions and regulations
as are from time to time charged or applicable to patrons of the Parking
Garage.  If, for any reason, Landlord fails or is unable to provide, or Tenant
is not permitted to use, all or any portion of the parking spaces to which it
is





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entitled under this paragraph, then Tenant's obligation to pay for such spaces
shall be abated for so long as Tenant does not have the use thereof; this
abatement shall be in full settlement of all claims that Tenant might otherwise
have against Landlord because of Landlord's failure or inability to provide
Tenant with such parking spaces.  If Tenant sublets any portion of the Premises
or assigns any of its interest in the Lease, then the total parking spaces
allocated to Tenant under the Lease, as amended hereby, shall be reduced to the
extent the ratio between the rentable square feet of the Premises and the
parking spaces granted to Tenant under the Lease as amended hereby exceeds the
Building standard ratio of parking space per rentable square foot as
established by Landlord from time to time.

       6.     Landlord and Tenant hereby confirm that Tenant has the right to
renew the Lease as it relates to the Additional Lease Area upon the terms and
conditions set forth in the Renewal Option described in Exhibit "F" attached to
the Lease.

       7.     Tenant warrants to Landlord that it has not dealt with any broker
or agent in connection with the negotiation or execution of this Amendment.
Landlord warrants to Tenant that it has not dealt with any broker or agent in
connection with the negotiation or execution of this Amendment, other than
Lincoln Property Company CSE, Inc.  Tenant and Landlord shall each indemnify
the other against all costs, expenses, attorneys' fees, and other liability
resulting to the other party by reason of a breach of the representation and
warranty made by such party in this paragraph 7.

       8.     Except as amended hereby the Lease remains in full force and
effect.  As of the effective date of this Amendment, Landlord and Tenant each
acknowledges to the other that neither party is in default under the Lease, as
amended hereby.  This Amendment may be executed in two or more counterparts,
each of which shall be deemed an original and all of which together shall
constitute one and the same instrument.

       IN WITNESS WHEREOF, Landlord and Tenant have executed this Amendment to
be effective as of the latest date accompanying a signature below.


                                      LANDLORD
                                      --------


                                      TRST IRVING, INC., a Texas corporation


Date: December 19, 1996               By: /s/ M. KEITH GARRISON                 
                                         ---------------------------------------
                                         Printed Name: M. Keith Garrison        
                                                      --------------------------
                                         Title: Vice President                  
                                               ---------------------------------





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<PAGE>   5
                                      TENANT
                                      ------


                                      I2 TECHNOLOGIES, INC., a Texas corporation


Date: December 10, 1996               By: /s/ DAVID F. CARY                     
                                         ---------------------------------------
                                         David F. Cary
                                         Chief Financial Officer





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<PAGE>   6

                                   EXHIBIT A


                      [5 pages of floor plans - graphics]


<PAGE>   7
                                   EXHIBIT B

                         TENANT FINISH-WORK: ALLOWANCE


1.     Tenant accepts Suite No. 1200 in its "as is" condition on the date that
       this Amendment is entered into and shall have the benefit of all
       existing improvements in Suite No. 1200 only.

2.     Tenant shall provide to Landlord for its approval space plans of Suite
       No. 1200 prior to commencing working drawings.  Following Landlord's
       written approval of such space plans, such approval not to be
       unreasonably withheld or delayed (such determination to be communicated
       within five (5) working days following submission by Tenant), Tenant
       shall provide to Landlord for its approval final working drawings,
       prepared by an architect that has been approved by Landlord (which
       approval shall not unreasonably be withheld), of all improvements that
       Tenant proposes to install in Suite No. 1200; such working drawings
       shall include the partition layout, ceiling plan, electrical outlets and
       switches, telephone outlets, drawings for any modifications to the
       mechanical and plumbing systems of the Building, and detailed plans and
       specifications for the construction of the improvements called for under
       this Exhibit in accordance with all applicable governmental laws, codes,
       rules, and regulations.  Landlord agrees to communicate its
       determination regarding the acceptability of such working drawing within
       ten (10) days following their submission by Tenant.  Further, if any of
       Tenant's proposed construction work will affect the Building's HVAC,
       electrical, mechanical, or plumbing systems, then the working drawings
       pertaining thereto shall be prepared by the Building's engineer of
       record, whom Tenant shall at its cost engage for such purpose.
       Landlord's approval of such working drawings shall not be unreasonably
       withheld, provided that (a) they comply with all applicable governmental
       laws, codes, rules, and regulations, (b) such working drawings are
       sufficiently detailed to allow construction of the improvements in a
       good and workmanlike manner, and (c) the improvements depicted thereon
       conform to the rules and regulations promulgated from time to time by
       Landlord for the construction of tenant improvements (a copy of which
       has been delivered to Tenant).  As used herein, "Working Drawings" shall
       mean the final working drawings approved by Landlord, as amended from
       time to time by any approved changes thereto, and "Work" shall mean all
       improvements to be constructed in accordance with and as indicated on
       the Working Drawings.  Approval by Landlord of the Working Drawings
       shall not be a representation or warranty of Landlord that such drawings
       are adequate for any use, purpose, or condition, or that such drawings
       comply with any applicable law or code, but shall merely be the consent
       of Landlord to the performance of the Work.  All changes in the Work
       must receive the prior written approval of Landlord, and in the event of
       any such approved change Tenant shall, upon completion of the Work,
       furnish Landlord with an accurate, reproducible "as-built" plan (e.g.,
       sepia) of the improvements as constructed, which plan shall be
       incorporated into the Lease by this reference for all purposes, as well
       as copies of all operating manuals, specifications and warranties on
       equipment installed and connected to
<PAGE>   8
       the Building's systems.

3.     The Work shall be performed only by contractors and subcontractors
       approved in writing by Landlord, which approval shall not be
       unreasonably withheld.  All contractors and subcontractors shall be
       required to procure and maintain (a) insurance against such risks, in
       such amounts, and with such companies as Landlord may reasonably require
       and (b) payment and performance bonds covering the cost of the Work and
       otherwise reasonably satisfactory to Landlord.  Certificates of such
       insurance, with paid receipts therefor, and copies of such bonds must be
       received by Landlord before the Work is commenced.  The Work shall be
       performed in a good and workmanlike manner that is free of defects and
       is in strict conformance with the Working Drawings, and shall be
       performed in such a manner and at such times as to maintain harmonious
       labor relations and not to interfere with or delay Landlord's other
       contractors, the operation of the Building, and the occupancy thereof by
       other tenants.  All contractors and subcontractors shall contact
       Landlord and schedule time periods during which they may use Building
       facilities in connection with the Work (e.g., elevators, excess
       electricity, etc.).

4.     Tenant shall bear the entire cost of performing the Work (including,
       without limitation, design of the Work and preparation of the Working
       Drawings, costs of construction labor and materials, electrical usage
       during construction, additional janitorial services, general tenant
       signage, related taxes and insurance costs, all of which costs are
       herein collectively called the "Total Construction Costs") in excess of
       the Construction Allowance (hereinafter defined).

5.     Landlord shall provide to Tenant a construction allowance (the
       "Construction Allowance") equal to the lesser of (a) $10.75 per rentable
       square foot in Suite No. 1200, or (b) the Total Construction Costs, as
       adjusted for any Landlord approved changes to the Work.  Tenant shall
       not become entitled to the Construction Allowance until the Work has
       been substantially completed and Tenant has caused to be delivered to
       Landlord (i) all invoices from contractors, subcontractors, and
       suppliers evidencing the cost of performing the Work, together with lien
       waivers from such parties, and a consent of the surety to the finished
       Work (if applicable), and (ii) a certificate of occupancy from the
       appropriate governmental authority, if applicable to the Work, or
       evidence of governmental inspection and approval of the Work.  Landlord
       agrees that up to $2.00 per rentable square foot (in Suite No. 1200) of
       the Total Construction Costs may be applied to architectural and
       engineering design costs.

6.     Tenant or its agent shall supervise the Work, make disbursements
       required to be made to the contractor.  Landlord or its agent
       (Landlord's Construction Manager) shall supervise the Work, and act as a
       liaison between the contractor and Tenant and coordinate the
       relationship between the Work, the Building, and the Building's systems.
       In consideration for such construction supervision services, Tenant
       shall pay to Landlord or its Agent a construction supervision fee equal
       to five percent (5%) of the Total Construction Costs.

7.     To the extent not inconsistent with this Exhibit, Sections 8a. and 8c of
       the Lease shall





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<PAGE>   9
       govern the performance of the Work and the Landlord's and Tenant's
       respective rights and obligations regarding the improvements installed
       pursuant thereto.

8.     a.     Tenant is responsible for bringing all areas of Suite No. 1200 in
              compliance with existing codes.  Without limiting the generality
              of the preceding sentence, Tenant shall be responsible to cause
              all areas, including without limitation the restrooms, in Suite
              No. 1200 to comply with applicable ADA standards for handicapped
              persons.  There are no Common Areas in Suite No. 1200.

       b.     Normal wear would include holes in walls to hang pictures or
              shelving, marks and scratches on the walls, and any electrical or
              mechanical equipment that can wear out with use.

       c.     Tenant shall prepare the bid package in accordance with AIA
              procedures.

       d.     A minimum of five contractors acceptable to Landlord, and two of
              which shall be recommended by Landlord, shall bid the work.

       e.     Tenant will contract with the lowest qualified bidder among the
              contractors.

       f.     Tenant shall not become entitled to the Construction Allowance or
              a portion thereof until the following occurs:  Each installment
              of work has been substantially completed in a workmanlike manner
              acceptable to the Landlord's Construction Manager.  The
              Construction Allowance will be paid not more often than monthly
              within thirty (30) days after Landlord's Construction Manager's
              receipt of invoice from Tenant or Tenant's Construction Manger,
              which shall include (i) all invoices from contractors,
              subcontractor, and suppliers evidencing the costs of performing
              the work, together with lien waivers from such parties, and (ii)
              with respect to the final payment only, a certificate of
              occupancy from the appropriate governmental authority, if
              applicable to the Work, or evidence of governmental inspection
              and approval of the Work.  In no event shall any one installment
              invoice by Tenant exceed an amount equal to (a) the percentage of
              completion times (b) the Total Construction Costs.