Item 1.01. Entry into a Material Definitive Agreement.
On March 31, 2009, Quanta Services, Inc. ("Quanta") entered into a Joinder Agreement and Fourth Amendment to Underwriting, Continuing Indemnity and Security Agreement (the "Joinder Agreement"), among Liberty Mutual Insurance Company, Liberty Mutual Fire Insurance Company and Safeco Insurance Company of America (collectively, the "New Co-Sureties"), American Home Assurance Company, National Union Fire Insurance Company of Pittsburgh, Pa., and The Insurance Company of the State of Pennsylvania (collectively, "AIG"), Federal Insurance Company ("Federal"), and the other parties designated therein as Indemnitors. Pursuant to the Joinder Agreement, the New Co-Sureties have been added as co-sureties to the Underwriting, Continuing Indemnity and Security Agreement dated March 14, 2005 among Quanta and the subsidiaries and affiliates of Quanta identified therein, AIG and Federal (the "Underwriting Agreement"), as amended by the Joinder Agreement and Amendment to Underwriting, Continuing Indemnity and Security Agreement dated November 28, 2006 (the "First Amendment"), by the Second Amendment to the Underwriting, Continuing Indemnity and Security Agreement dated January 9, 2008 (the Second Amendment") and by the Joinder and Third Amendment to Underwriting, Continuing Indemnity and Security Agreement dated December 19, 2008. The foregoing summary of some of the terms of the Joinder Agreement is qualified in its entirety by reference to the complete text thereof, a copy of which is filed as an exhibit to this report and is incorporated herein by reference. The Underwriting Agreement was previously filed as Exhibit 10.1 to the Company's Form 8-K filed on March 16, 2005. The First Amendment was previously filed as Exhibit 99.1 to the Company's Form 8-K filed on December 4, 2006. The Second Amendment was previously filed as Exhibit 10.34 to the Company's Form 10-K filed on February 29, 2008. Item 9.01. Financial Statements and Exhibits.
(d) Exhibits

Exhibit No. Exhibit 99.1 Joinder Agreement and Fourth Amendment to Underwriting, Continuing Indemnity and Security Agreement, dated as of March 31, 2009, among American Home Assurance Company, National Union Fire Insurance Company of Pittsburgh, Pa., The Insurance Company of the State of Pennsylvania, Liberty Mutual Insurance Company, Liberty Mutual Fire Insurance Company, Safeco Insurance Company of America, Federal Insurance Company, Quanta Services, Inc., and the other Indemnitors identified therein.

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