FIFTH AMENDMENT TO LEASE AGREEMENT GRE EMPIRE TOWERS LP,

EXHIBIT 10.7.4

FIFTH AMENDMENT TO LEASE AGREEMENT

GRE EMPIRE TOWERS LP,

a Delaware limited partnership

(“LANDLORD”)

AND

KAISER VENTURES, LLC,

a Delaware limited liability company,

p/k/a Kaiser Resources, Inc.

(“TENANT”)

This Fifth Amendment to Lease Agreement (“Fifth Amendment”), is made as of March 16, 2009, by and between GRE EMPIRE TOWERS LP, a Delaware limited partnership (“Landlord”), and KAISER VENTURES, LLC, a Delaware limited liability company, p/k/a Kaiser Resources, Inc.(“Tenant”).

RECITALS

A. Landlord is the Owner of Empire Towers I located at 3633 E. Inland Empire Boulevard, Ontario, California (“Building”) and is the successor Landlord to Empire Towers I LLC, a California limited liability company, which was the successor Landlord to Lord Baltimore Capital Corporation previously known as American Trading Real Estate Properties, Inc. under that certain Lease Agreement and Addendum thereto dated June 6, 1994 (“Original Lease”), amended by a First Amendment to Lease Agreement dated May 18, 1999 (“First Amendment”), a Second Amendment to Lease Agreement dated September 27, 1999 (“Second Amendment”), a Third Amendment to Lease Agreement dated February 19, 2002 (“Third Amendment”), and a Fourth Amendment to Lease Agreement dated November 13, 2006 (“Fourth Amendment”) (collectively referred to as “Lease Agreement”), for Suite 480 comprising approximately three thousand one hundred twenty-eight (3,128) gross rentable square feet (“Premises”). Tenant is the Tenant under the Lease Agreement.

B. Landlord and Tenant desire to further amend the Lease Agreement on the terms and conditions provided below.

AGREEMENTS

NOW, THEREFORE, in consideration of the mutual covenants contained herein and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties agree as follows:

1. Incorporation of Recitals. All of the recitals set forth above are hereby made an integral part of this Fifth Amendment.

2. Definitions. All capitalized terms not otherwise defined in this Fifth Amendment herein shall have the meaning ascribed to them in the Lease Agreement.

3. Term. Notwithstanding any provision to the contrary contained in the Lease

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Agreement, including, without limitation, Section 3.01 of the Original Lease, Section 3 of the First Amendment, Section 3 of the Third Amendment, and Section 3 of the Fourth Amendment, the term of the Lease Agreement for the Premises is hereby extended for a period of twenty-four (24) months commencing September 1, 2009 and expiring August 31, 2011 (“Fourth Extended Term”).

4. Base Rent for the Premises. The monthly Base Rent for the Demised Premises during the Fourth Extended Term shall be as follows:

Notwithstanding anything to the contrary set forth in the Lease Agreement, Base Rent during the period from June 1, 2009, through August 31, 2009, shall be abated in its entirety.

5. Base Taxes. As of September 1, 2009, Base Taxes for the Demised Premises shall mean Taxes for the calendar year 2009.

6. Base Operating Costs. As of September 1, 2009, Base Operating Costs for the Demised Premises shall mean Operating Costs for the calendar year 2009.

7. Tenant Improvements. On or before September 30, 2009, Landlord shall, at Landlord’s sole cost and expense (i) professionally clean the existing carpeting in the Demised Premises, and (ii) paint the Demised Premises utilizing Building Standard paint. Other than the foregoing, Landlord shall have no obligation to prepare the Demised Premises for Tenant’s continued occupancy during the Fourth Extended Term.

8. Option to Extend Term. All options to extend the term of the Lease Agreement, if any, set forth in the Lease Agreement are hereby deleted in their entirety, including, without limitation, Article 43 of the First Amendment and Section 8 of the Fourth Amendment, and are replaced by the Option to Extend the Term described in this Section 8 of this Fifth Amendment. Provided Tenant has cured any default of the Lease Agreement in the prescribed time and manner described in the Lease Agreement at any time from the time Tenant exercises the applicable option as set forth herein until such time as such extended term commences, Tenant shall have two (2) options to extend the term (each an “Option to Extend the Term”) of this Lease Agreement for an additional period of twelve (12) months each (each an “Additional Extended Term”) immediately following the expiration date of the Fourth Extended Term and the first Additional Extended Term, as applicable. To exercise each option, Tenant must give written notice to Landlord at least six (6) months, but not more than nine (9) months, prior to the expiration date of the Fourth Extended Term or the first Additional Extended Term, as applicable. Time is agreed to be of the essence with respect to this notice requirement.

In the event Tenant effectively exercises each such option, the annual base rent (“Annual

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Base Rent”) for the Demised Premises over the applicable Additional Extended Term shall be the then fair market rental rate per rentable square foot of the Demised Premises per annum as determined by Landlord. Landlord shall advise Tenant in writing of the then fair market rental rate for the Demised Premises. As used herein, “fair market rental rate” shall mean the annual rate per rentable square foot that Landlord could reasonably expect to obtain from a third party desiring to lease the Demised Premises within the Ontario Airport submarket for the applicable Additional Extended Term, taking into account all allowances, concessions and commissions. If Tenant accepts Landlord’s statement of such fair market rental rate in writing within thirty (30) days of receipt of Landlord’s statement of the same, the Base Taxes and Base Operating Costs during the applicable Additional Extended Term shall be the actual Taxes and Operating Costs for calendar year two thousand nine (2010) for the first Additional Extended Term, and for calendar year two thousand eleven (2011) for the second Additional Extended Term. If Tenant objects to the fair market rental rate submitted by Landlord within such thirty day period, Landlord and Tenant will attempt in good faith to agree upon such fair market rental rate using their best good faith efforts. If Landlord and Tenant fail to reach agreement on such fair market rental rate within fifteen (15) days thereafter, then either Landlord or Tenant may terminate the applicable Option to Extend the Term upon written notice to the other party.

Each Option to Extend the Term may only be exercised as to the entire Demised Premises and any attempt to exercise an Option to Extend the Term as to any portion of the Demised Premises, but not as to the entire Demised Premises, shall be null and void. The second Option to Extend the Term shall be null and void unless Tenant has validly exercised the first Option to Extend the Term.

Each Option to Extend the Term shall be personal to the original Tenant hereunder named Kaiser Venture, LLC and shall be immediately null and void and of no effect if such original Tenant assigns the Lease Agreement with or without Landlord’s consent in accordance with Article VI of the Lease Agreement.

Except as otherwise provided in this Article, all of the covenants, terms and conditions of this Lease Agreement shall apply in full force and effect during each Additional Extended Term except that (i) any financial incentives; (ii) any construction work; (iii) any options to reduce, extend, expand, terminate; and (iv) any rights of first refusal, offer or negotiation previously provided to Tenant shall not be applicable to each Additional Extended Term.

Prior to the first day of each Additional Extended Term, Landlord shall prepare and Landlord and Tenant shall execute an amendment to the Lease Agreement for the purpose of confirming the above.

9. No Brokers. Landlord and Tenant acknowledge that CIP Real Estate Property Services (the “Landlord’s Broker”) represented Landlord in this transaction and Tenant was not represented by a broker. Landlord and Tenant each represent and warrant to each other that it has not had any dealing with any other real estate broker or finder with respect to this First Amendment and agree to hold each other harmless from and against any and all damages, costs, expenses resulting from any claim(s) for a brokerage commission or finder’s fee that may be asserted against either of them by any broker or finder with whom the other has dealt or with whom such other broker or finder claims to have dealt with.

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10. No Defaults. To Tenant’s actual knowledge, (i) there are no defaults of Landlord or Tenant under the Lease Agreement or any existing conditions, which upon giving notice or lapse of time or both would constitute a default under the Lease Agreement and (ii) there are no offsets or credits against the payment of rent due under the Lease Agreement.

11. Authority. Each party hereto warrants that the person signing below on such party’s behalf is authorized to do so and to bond such party to the terms of this Fifth Amendment.

12. Effective of Fifth Amendment, Affirmation of Lease Agreement. Except for any financial incentives or construction work previously provided Tenant and except as specifically amended and modified by this Fifth Amendment, the Lease Agreement is hereby affirmed and remains in full force and effect. In the event of any conflict between the terms of this Fifth Amendment and the Lease Agreement, the terms and conditions of this Fifth Amendment shall prevail.

IN WITNESS WHEREOF, the parties hereto have executed this Fifth Amendment on the date set forth opposite their respective signatures below.

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