FIRST AMENDMENT TO LEASE

Exhibit 10.1

FIRST AMENDMENT TO LEASE

THIS FIRST AMENDMENT TO LEASE dated as of June 19, 2008 (this “First Amendment”) is entered into by and between MARY AVENUE OFFICE, LLC , a California limited liability company, as successor-in-interest to Mary Avenue Office LLC, (“Lessor”), and BLUE COAT SYSTEMS, INC. , a Delaware corporation (“Lessee”), with reference to the following:

R E C I T A L S

A. Lessor and Lessee are parties to that certain Triple Net Space Lease dated April 21, 2005 (the “Original Lease”) for the lease of certain premises (the “Existing Premises”), consisting of that certain approximately 116,586 square foot building (the “Building”) located at 420 North Mary Avenue in Sunnyvale, California. All capitalized terms used herein and not otherwise defined herein shall have the meanings ascribed to such terms in the Lease; and

B. The term of the Original Lease is scheduled to expire on August 31, 2010.

C. Lessor and Lessee desire by this First Amendment to amend the Lease in order to, among other things, (i) include the “New Premises” described in Section 2 below as part of the Premises leased to Lessee under the Lease; (ii) extend the term of the Lease with respect to the Existing Premises and provide for a new term with respect to the New Premises; (iii) provide for the monthly rent to be paid by Lessee for the Existing Premises during the Extension Term (as defined below) and for the New Premises during the New Premises Term (as defined below); and (iv) further amend, modify and supplement the Lease as set forth herein.

NOW, THEREFORE, in consideration of the Premises and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Lessor and Lessee hereby agree as follows:

1. Recitals & References . The Recitals set forth above are incorporated herein as though set forth in full herein. All references to the “Lease” or “lease” appearing in this First Amendment or in the Original Lease shall mean, collectively, this First Amendment and the Original Lease as amended by this First Amendment.

2. Expansion of Premises . Effective as of the New Premises Commencement Date (as hereinafter defined), certain space in the amount of 116,586 square foot building commonly known as 410 North Mary Avenue in Sunnyvale, California and located in the Project, as shown on Exhibit A attached hereto (the “New Premises”), shall be added to the Lease. The Existing Premises and the New Premises shall be comprised of 233,172 square feet of aggregate Rentable Area and shall be collectively referred to as the “Premises”. The Premises are also shown on Exhibit A attached hereto.

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3. Term .

(a) New Premises Term . As used herein, the term “New Premises Commencement Date” shall mean the earlier of (i) Lessee’s occupancy of the New Premises for the conduct of business therein or (ii) November 1, 2008, provided that Lessor has delivered possession of the New Premises to Lessee by such date. The term of the Lease with respect to the New Premises shall commence on the New Premises Commencement Date and expire on November 30, 2015(the “New Premises Expiration Date”), unless sooner terminated as provided for in the Lease. The period from the New Premises Commencement Date through the New Premises Expiration Date shall be referred to herein as the “New Premises Term”.

b. Extension of Term for Existing Premises. Lessor and Lessee acknowledge that the current term of the Lease with respect to the Existing Premises expires according to its terms on August 31, 2010. Notwithstanding anything to the contrary contained in the Lease, Lessor and Lessee agree that the term of the Lease with respect to the Existing Premises is hereby extended such that it shall expire on November 30, 2015, unless sooner terminated as provided for in the Lease. The period from September 1, 2010 through November 30, 2015 shall be referred to herein as the “Extension Term”.

c. Term. The New Premises Term and the Extension Term are collectively referred to as the “Terms”.

4. Early Entry . Upon the mutual execution of this First Amendment, and provided that Lessee has delivered to Lessor the New Letter of Credit (as defined below), certificates evidencing the insurance required under the Lease, Lessee and its employees and contractors may enter the New Premises, at Lessee’s sole risk, for the sole purpose of installing Lessee’s trade fixtures, equipment, telecommunications systems and other equipment therein and for constructing the Lessee Improvements (as defined in the Work Letter attached hereto as Exhibit B ) to be made to the New Premises. Lessee’s occupancy of the New Premises prior to the New Premises Commencement Date shall be on all of the terms and conditions of this Lease (including but not limited to the obligation to pay utilities supplied to the Premises pursuant to Section 10.01 of the Lease), except the obligation to pay Base Rent, Operating Expenses and real property taxes allocable to the New Premises.

5. Option to Extend . The Option to Extend the Lease Term granted to Lessee pursuant to Section 3.02(a) of the Lease is hereby terminated and null and void. Lessee shall instead have two (2) options (collectively, the “New Extension Options”) to extend each of the Terms for periods of five (5) years each, on the same terms and provisions contained in the Lease, except that the Base Rent payable by Lessee during any such extended term shall be equal to one hundred percent (100%) of the Fair Market Rent for the Premises (as that term is defined in Section 3.02 of the Lease) as of the commencement of such extended term. Lessee shall exercise such New Extension Options, if at all, by providing Lessor with written notice thereof no sooner than twelve (12) months nor later than nine (9) months prior to the expiration of the then-applicable term or renewal term, as applicable, for the New Premises or Existing Premises, whichever is earlier. Lessee’s exercise of the above New Extension Options shall otherwise be subject to the remaining terms and provisions contained in Section 3.02 of the Lease, including but not limited to the conditions for exercise of the Option to Extend set forth Section 3.02(a). Lessee may only exercise the foregoing New Extension Options with respect to the entire Premises, and may not selectively exercise the New Extension Options solely for either the Existing Premises or the New Premises.

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6. Monthly Rent .

a. New Premises Rent. In addition to paying all other amounts due under the Lease with respect to the New Premises, Lessee shall pay monthly base rent for the New Premises during the New Premises Term as follows:

New Premises Base Rent

b. Existing Premises Rent. Notwithstanding anything in the Lease to the contrary and in addition to paying all other amounts due under the Lease with respect to the Existing Premises, Lessee shall pay monthly base rent for the Existing Premises during the Extension Term as follows:

Existing Premises Base Rent

c. Additional Rent. Lessee shall pay Lessee’s Share of Additional Rent (as provided for in Section 12(a) below) for the Existing Premises during the Extension Term and for the New Premises during the New Premises Term and any extensions thereof as provided for in Section 4.03 of the Lease.

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7. Letters of Credit Security . Lessor is currently holding a letter of credit security in the amount of Eight Hundred Sixty-One Thousand Four Hundred Sixteen and 60/100 Dollars ($861,416.60), which was delivered by Lessee to Lessor pursuant to Section 4.06 of the Lease (the “Existing Letter of Credit Security”). Upon execution of this First Amendment, Lessee shall deposit with Lessor an unconditional, irrevocable letter of credit in substantially the same form as the Existing Letter of Credit Security, in an amount of Eight Hundred Forty-Nine Thousand Nineteen & 20/100 Dollars ($849,019.20) (the “New Letter of Credit Security”), which New Letter of Credit Security shall replace the Existing Letter of Credit Security. The New Letter of Credit Security will be subject to all of the terms and conditions applicable to the Existing Letter of Credit Security set forth in Section 4.06 of the Lease. Promptly upon receipt of the New Letter of Credit Security, Lessor shall return the Existing Letter of Credit Security to Lessee.

8. Condition of the Premises .

a. Existing Premises. Lessee acknowledges that it has been and continues to be in possession of the Existing Premises, is familiar with the condition of the Existing Premises and accepts the Existing Premises in its presently existing, “AS IS” and “WITH ALL FAULTS” condition, without representation, warranty or improvements by Lessor of any kind whatsoever.

b. New Premises. Lessor represents and warrants to Lessee that upon delivery of the New Premises to Lessee, the Building roof shall be in water-tight condition and the base building plumbing, electrical, elevators, bathroom cores and roll up doors in good working condition and the interior and exterior of the Building in compliance (without regard to the specific use for which Lessee will use the New Premises) with Title III of the Americans with Disabilities Act of 1990. In the event that Lessee determines, and Lessee notifies Lessor in writing within nine (9) months after the New Premises Commencement Date, that any of the obligations of Lessor set forth in this Section 8(b) were not performed, and such failure is not due to Alterations or Tenant Improvements to the Premises made by Lessee or Lessee’s activities at the Premises, then it shall be the obligation of Lessor (and together with its rights under Section 12.03 of the Lease the sole right and remedy of Lessee), after receipt of written notice from Lessee setting forth with specificity the nature of the failed performance, to promptly, within a reasonable time and at Lessor’s sole cost, correct same. Except as to certain defects which remain Lessor’s responsibility under Section 6.01(b) of the Lease, Lessee’s failure to give such written notice to Lessor within nine (9) months after the New Premises Commencement Date shall constitute a conclusive presumption that Lessor has complied with all of Lessor’s obligations under the foregoing Section 8(b), and any required correction after that date shall be performed by Lessee, at its sole cost and expense.

c. HVAC System. Additionally, Lessor shall, at Lessor’s sole expense, replace the existing heating, ventilation and air conditioning (“HVAC”) system serving the New Premises with an HVAC system of similar tonnage to that in the Existing Premises and provide a Building Management System pursuant to the scope of work outlined in Exhibit C. Subject only to the foregoing (including, but not limited to Section 8(b)) and Sections 5.04 and 6.01(b) of the Lease, and having made such inspection of the New Premises, Building and Project as it deemed prudent and appropriate (including, without limitation, testing for the presence of mold), Lessee hereby accepts the New Premises in their present condition existing as of the New Premises Commencement Date, “AS IS” and “WITH ALL FAULTS” subject to all

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applicable zoning, municipal, county and state laws, ordinances and regulations governing and regulating the use and condition of the New Premises and any covenants or restrictions, liens, encumbrances and title exceptions of record. Except as otherwise expressly set forth herein, Lessee acknowledges that neither Lessor nor any agent of Lessor has made any representation or warranty as to the present or future suitability of the New Premises for the conduct of Lessee’s business. Lessor shall reimburse tenant for all costs associated with installation of all pneumatic controls, as well as repair of existing VAV boxes as necessary, which reimbursement shall not be deemed to constitute part of the New Premises Allowance; provided however, that Lessor shall have the option, at Lessor’s election, to install the foregoing pneumatic controls and perform any such necessary repairs to the existing VAV boxes itself.

9. Right of First Offer . As of the date of this First Amendment, Section 17.24 of the Lease is hereby terminated and deleted in its entirety and replaced with the following:

a. Grant . Subject to the terms of this Section 17.24, Lessor grants to Lessee during the Right of First Offer Term (as defined below) a one time only right of first offer (“Right of First Offer”) to lease any space which is available for lease in the building located at 430 North Mary Avenue in the Project (“Available Space”). For the purposes of this Section 17.24, such space shall not be deemed available for lease, and this Right of First Offer shall not apply, if the space in question is already leased to a tenant thereof who leases or re-leases such space pursuant to any then-existing or future right to extend the term of its lease or expand the size of its premises agreed upon in writing by Lessor and such tenant.

b. Term. The term of the Right of First Offer (“Right of First Offer Term”) shall commence on the New Premises Commencement Date of this Lease and shall terminate on the New Premises Expiration Date.

c. Covenants of Lessor. Subject to the conditions precedent established by subsection (e) below, if at any time during the Right of First Offer Term Lessor decides to offer any Available Space for lease to a bona fide third party, Lessor shall first provide Lessee with a written notice (“Offer Notice”) detailing (i) the rent at which said Available Space is being offered to the third party, (ii) the rentable square footage and location thereof, (iii) the date the Available Space will become available and (iv) all other terms upon which Lessor proposes to lease the Available Space to Lessee.

d. Exercise of Lessee’s Right of First Offer. Subject to the conditions precedent established by subsection (e) below, Lessee may exercise Lessee’s Right of First Offer to lease all (but not less than all) of the Available Space described in the Offer Notice by providing Lessor with written notice (“Acceptance Notice”) thereof within five (5) business days of Lessor’s delivery to Lessee of the Offer Notice. If Lessee does not exercise its Right of First Offer within said five (5) business day period, Lessor shall be relieved of Lessor’s obligation to lease the Available Space mentioned in the Offer Notice to Lessee and the provisions of this Section 9 shall not apply to Lessor, except if Lessor, within one hundred twenty (120) days after the date of the Offer Notice, offers the Available Space for the same time period specified in the Offer Notice at a base rent which is less than ninety percent (90%) of the base rent specified in the Offer Notice, Lessor shall first re-offer such space to Lessee with those new terms and Lessee shall have the right to exercise such new Offer Notice within the time period set forth in this Subsection 17.24.

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e. Conditions to Right of First Offer. Notwithstanding anything to the contrary in this Section 17.24, Lessor shall have no obligation to provide Lessee with an Offer Notice, and Lessee shall have no right to exercise Lessee’s Right of First Offer, if: (i) Lessee is in default either: (a) at the time Lessor seeks to lease the Available Space in question, or at the time Lessee seeks to give Lessor an Acceptance Notice, whichever, is relevant, or (b) upon the date Lessee seeks to take possession of the Available Space referenced in the Offer Notice, (ii) Lessee has assigned this Lease or sublet more than fifty percent (50%)of the rentable space located in the Premises to a party other than an Affiliate, (iii) Lessee then occupies less than fifty (50%) of the Premises; or (iv) Lessee has received more than three (3) notices of defaults from Lessor during the Term of this Lease. Lessee’s Right of First Offer shall be personal to Lessee and Lessee’s Affiliate and shall not be transferable with any assignment of this Lease or subletting of the Premises, in each instance except to an Affiliate.

f. Terms for Right of First Offer. In the event that Lessee exercises Lessee’s Right of First Offer, Lessee’s occupancy of the Available Space taken shall be on all of the same terms and conditions described in the Offer Notice, except that the Base Rent due for the Available Space taken shall be one hundred percent (100%) of the Fair Market Rent (as defined in Section 3.02(b) of the Lease) for such Available Space. In such event, Lessee’s Share due hereunder shall also be adjusted accordingly.

g. Amendment to Lease. Lessor and Lessee hereby agree to execute an amendment to this Lease (“Lease Amendment”) prior to Lessee’s occupancy of the Available Space in question. The Lease Amendment shall specify, among other things, the Rent, date of occupancy, increase in Lessee’s Share and square footage of the Available Space taken in connection with Lessee’s exercise of Lessee’s Right of First Offer. If Lessee does not execute such a Lease Amendment within the later of (a) five (5) business days of Lessor’s presentation of a Lease Amendment properly embodying the terms of the Offer Notice (as may be amended upon the mutual agreement of the parties); and (b) fifteen (15) business days after the date on which it provides Lessor with the Acceptance Notice, then, at Lessor’s option, Lessee’s rights hereunder shall be void and terminated, but, otherwise, a valid exercise of Lessee’s Right of First Offer shall be fully effective, whether or not such amendment is executed.

10. Parking . All provisions of Section 2.03 remain in full force and effect. Lessee shall continue to have the non-exclusive use of its proportionate share of the parking spaces located within the Common Area, which is currently three and one-half (3.5) spaces per one thousand (1,000) square feet of usable space within the Premises. Currently ten (10) of Lessee’s proportionate share of the parking spaces are marked for Lessee’s exclusive use pursuant to Section 2.03 of the Lease and the parking podium, while still considered part of the Common Area, shall continue to be for the exclusive use of Lessee.

11. Furniture . Notwithstanding anything to the contrary in the Lease, Lessor and Lessee acknowledge that no furniture is being leased to Lessee in connection with the lease of the New Premises.

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12. Operating Expenses .

a. Lessee’s Share . Notwithstanding anything to the contrary in the Lease, as of the New Premises Commencement Date, Lessee’s Share of Operating Expenses for the Project shall be sixty-six and two thirds percent (66.7%). The limitations on Lessee’s Share of Operating Expenses during the first eighteen (18) months of the Lease Term set forth in Section 4.04(c) of the Lease are not applicable to the Extension Term or New Premises Term and are hereby deleted.

b. Capital Expenditures. As of the New Premises Commencement Date, the thresholds relating to capital expenditures set forth in the second paragraph of Section 4.04(a) shall be increased as follows: If Lessee’s Share of the cost of any particular capital expenditure to the Project exceeds Thirty Thousand Dollars ($30,000), or if Lessee’s Share of the cost of any particular capital expenditure in either the New Premises or the Existing Premises exceeds Thirty Thousand Dollars ($30,000) (the “Premises Capital Expenditure Limit”), then such cost shall be amortized over its useful life and the amount includible in Operating Expenses shall be limited to the monthly amortized cost thereof. The Premises Capital Expenditure Limit shall now apply to the Premises on a per-building basis.

13. Insurance Deductibles . Section 7.01 of the Lease is hereby amended to provide that, Lessee’s Share of any deductibles under any insurance policy carried by Lessor with respect to the Premises shall not exceed One Million Dollars ($1,000,000).

14. Lessee Improvements . Upon execution of this First Amendment, Lessor and Lessee shall also execute the Work Letter attached hereto as Exhibit B (the “Work Letter”). Lessee shall cause certain Lessee Improvements (as defined therein) to be performed to the New Premises and Existing Premises pursuant to the terms of the Work Letter. Lessee shall not be required to remove or restore the initial improvements made by Lessee to the New Premises pursuant to the Work Letter. However, all subsequent alterations and additional improvements shall be subject to the provisions of Section 6.03 of the Lease.

15. Stairwell .

a. New Premises. Lessor hereby consents to Lessee’s addition of a stairwell between the second and third floors of the New Premises, provided that the design, construction and installation of such stairwell shall be subject to the terms and conditions of Section 6.03 of the Lease. The stairwell shall be similar to the stairwell added by Lessee to the Existing Premises and all costs associated with the addition of the stairwell shall be Lessee’s sole responsibility. Lessee shall, subject to Lessor’s reasonable approval, select a contractor to construct the stairwell. Lessor agrees that Lessee shall not be required to remove the stairwell installed in the New Premises upon expiration or earlier termination of the Lease.

b. Existing Premises. Lessor hereby agrees that Lessee shall not be required to remove the stairwell installed by Lessee between the second and third floors of the Existing Premises upon expiration or earlier termination of the Lease. The New Letter of Credit Security shall not include any amount for restoration of the stairwell in the Existing Premises.

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16. Fencing . Subject to approval by the City of Sunnyvale, Lessee shall have the right, at Lessee’s sole cost and expense, to construct a fence (type and height to be approved by Lessor, in Lessor’s reasonable discretion, prior to commencement of construction) at the rear of the Project and behind the parking structure. Without limiting the foregoing, such fence shall be consistent with the quality of the Project in general.

17. Satellite Dish . Tenant may install a satellite dish and other similar communications equipment on the roof of the New Premises, subject to the terms and conditions of Section 17.25 of the Lease.

18. Alterations . Section 6.03 of the Lease states that Lessee may make certain Alterations without Lessor’s consent if the cost of such Alterations does not exceed collectively One Hundred Twenty Thousand Dollars ($120,000) in any twelve (12) month period (the “Alterations Limit”). The Alterations Limit shall now apply to the Premises on a per-building basis.

19. Lessor’s Recapture Rights . Subsection 11.06 of the Lease gives Lessor the right to respond to a request by Lessee to assign the Lease or sublet or otherwise transfer more than fifty percent (50%) of the Premises (the “Recapture Threshold”) for more than fifty percent (50%) of the Lease Term by recapturing the “Recapture Space” on the terms described therein. The Recapture Threshold shall now apply to the Premises on a per-building basis.

20. Signage . As of the date of this First Amendment, Section 17.15 of the Lease is hereby terminated and deleted in its entirety and replaced with the following:

a. Building and Monument Signs. Subject to the terms of this Section 17.15 and the Lease, Lessee may, at Lessee’s sole expense, install signage: (i) on the exterior of the building in which the Existing Premises is located, (ii) on the exterior of the building in which the New Premises is located, and (iii) on sixty-six and two-thirds percent (66 and 2/3%) of the monument signage for the Project. In addition, Lessee may also install directional signage on the grounds of the New Premises, Existing Premises and Common Areas, subject to the provisions of this Section 17.15.

b. Installation of Lessee’s Signs. Lessee shall not place any sign outside (or visible from the outside) of the New Premises or Existing Premises without Lessor’s prior written consent, which consent shall not be unreasonably withheld, and subject to Lessee’s obtaining approval by the City of Sunnyvale. Lessee, at its sole cost and expense, after obtaining Lessor’s prior written consent, shall install, maintain and remove prior to expiration of this Lease (or within ten (10) days after any earlier termination of this Lease) all signage in full compliance with (i) all applicable laws, statutes, ordinances and regulations, (ii) all provisions of this Lease concerning Alterations and (iii) Lessor’s signage policy set forth in Exhibit “C” of the Lease.

c. Illuminated Signage. Lessor is currently working with Lessor’s sign consultant and the City of Sunnyvale Planning Department to develop building signage criteria that includes the provision for Lessee to install a back lit (halo illumination) sign on the exterior of the Existing Premises and the New Premises. Said criteria will be based on Lessor’s reasonable judgment of appropriate sign standards and locations for the Project, and City of

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Sunnyvale Planning codes as they pertain to illuminated signs. Furthermore, without limiting the foregoing, Lessee acknowledges that all of Lessee’s signage at the Project must be aesthetically uniform and as a result, if Lessee, subject to the foregoing requirements, installs any new back lit signage with respect to the New Premises or otherwise, it will be also required to modify its other building signage (including, but not limited to, the building signage for the Existing Premises) so as to maintain consistency among the same.

d. Termination of Right. Notwithstanding anything to the contrary in this Section 17.15 or the Lease, Lessee’s right to maintain a sign on a building leased by Lessee shall immediately cease and Lessee shall upon demand remove the signage on the exterior of the applicable building in accordance with Subsection 17.15(f) below if Lessor shall exercise Lessor’s recapture rights pursuant to Section 11.06 of the Lease. The foregoing termination of right shall apply on a per building basis.

e. Garage Signage. Subject to the terms of this Section 17.15 and the Lease, Lessee may, at Lessee’s sole expense, paint Lessee’s logo on the top deck of the parking podium structure.

f. Removal. Upon the expiration or earlier termination of this Lease or of Lessee’s right to maintain any of the building, monument or other signs described herein, Lessee shall, at Lessee’s sole cost and expense, remove such signs, repair any damage caused by such removal and return the area in which such sign was located to the condition in which it existed prior to the installation of such sign.

21. Estoppel . Lessee hereby certifies and acknowledges, that as of the date hereof, to the best of Lessee’s knowledge, (a) Lessor is not in default in any respect under the Lease, (b) Lessee does not have any defenses to its obligations under the Lease, and (c) there are no offsets against rent payable under the Lease, except for prepaid rent through June 30, 2008 (not to exceed one month). Lessee acknowledges and agrees that: (i) the representations herein set forth constitute a material consideration to Lessor in entering into this First Amendment; (ii) such representations are being made by Lessee for purposes of inducing Lessor to enter into this First Amendment; and (iii) Lessor is relying on such representations in entering into this First Amendment.

22. Brokers . Each party hereby repr