WAIVER AGREEMENT

Exhibit 10.10

WAIVER AGREEMENT

     This WAIVER AGREEMENT (this “Agreement”) is made and entered into as of this 21st day of February, 2011, by and between Xxxxx Corporation, a Delaware corporation (“Xxxxx”), and Xxxxx X. Xxxx (the “Employee”).

     Reference is hereby made to that certain Agreement and Plan of Merger, dated as of even date herewith (the “Merger Agreement”), by and among Xxxxx, North Acquisition, Inc., a Wyoming corporation (“Merger Sub”) and Frontier Oil Corporation, a Wyoming corporation (“Frontier”), pursuant to which, subject to the terms and conditions contained therein, Merger Sub will be merged with and into Frontier (the “Merger”), with Frontier remaining the surviving corporation in the Merger and becoming a wholly-owned subsidiary of Xxxxx. Capitalized terms used herein and not defined shall have the meanings ascribed to them in the Merger Agreement.

     Now, therefore, in consideration of the mutual covenants contained herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Xxxxx and the Employee agree as follows:

     1. Effective Time. The agreements set forth in Section 2 below shall become effective immediately prior to the Effective Time of the Merger; provided, that if the Closing does not occur in accordance with the terms of the Merger Agreement, this Agreement shall terminate and have no further force or effect without the need for any additional action by Xxxxx or the Employee.

     2. Waiver. Employee hereby acknowledges and agrees that the change in his title from Senior Vice President and Chief Financial Officer to Senior Vice President of Strategy and Corporate Development, and any associated changes in his employment authority, duties or responsibilities with Xxxxx following the consummation of the Merger that are consistent with such change in title, shall not constitute a material reduction or other change in the Employee’s authority, duties or responsibilities for purposes of the definition of “Adverse Change” contained in any equity award listed on Exhibit A hereto. For the avoidance of doubt, a material reduction in salary, benefits, bonus targets and/or long term incentive grants that does not apply generally to executives of Xxxxx and its subsidiaries (including Frontier and its subsidiaries following the Closing of the Merger) and all of their successors, would constitute an “Adverse Change” and is not waived by this Agreement.

     3. Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware without regard to conflict of law principles.

     4. Entire Agreement. This Agreement constitutes the complete agreement between the parties with regard to the subject matter hereof and supersedes all prior oral or written agreements or understandings with respect to the subject matter hereof.

     5. Successors and Assigns. The provisions hereof shall inure to the benefit of, and be binding upon, the successors, assigns, heirs, executors, and administrators of the parties hereto.

     6. Counterparts. This Agreement may be executed in one or more counterparts, including by electronic mail, facsimile and portable document format (.pdf) delivery, each of which shall be deemed to be an original and all of which together shall constitute one and the same instrument.

[Signature Page Follows]

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date first above written.

	EMPLOYEE:
	By:	/s/Xxxxx X.Xxxx
		Bruce X.Xxxx
	HOLLY CORPORATION
	By:	/s/Xxxxxxx X. Xxxxxxx
		Name:	Xxxxxxx X. Xxxxxxx
		Its:	Chief Executive Officer

[Signature Page to Waiver Agreement]

Exhibit A

List of Applicable Agreements

Total outstanding equity awards: 17,354 shares/units. From Xxxxx: 14,777 shares outstanding; From HEP: 2,577 units outstanding. All outstanding shares or units with a performance standard are being reported at 100% level (i.e., target level).

	1.		Restricted Stock Unit Agreement with Xxxxx Corporation, dated February 2009: 1,708 shares outstanding (no performance standard)
	2.		Restricted Stock Unit Agreement with Xxxxx Corporation, dated March 2010: 3,124 shares outstanding (no performance standard)
	3.		Performance Share Unit Agreement with Xxxxx Corporation, dated February 2009: 5,124 units outstanding
	4.		Performance Share Unit Agreement with Xxxxx Corporation, dated March 2010: 4,821 units outstanding
	5.		Restricted Stock Unit Agreement with Xxxxx Energy Partners/Xxxxx Logistics Services, dated 2009: 1,109 units outstanding
	6.		Restricted Stock Unit Agreement with Xxxxx Energy Partners/Xxxxx Logistics Services, dated 2010: 1,468 units outstanding