Exhibit 99.1 Atlantic Holdings Corporation 4 Paragon Way, Freehold, New Jersey 07728 (732) 665-1100 Facsimile: (732) 761-0243 NASDAQ: NAHC CONFIDENTIALITY AND STANDSTILL AGREEMENT September 22, 2006 The Commerce Group, Inc. 211 Main Street Webster, MA...Confidentiality and Standstill Agreement • September 26th, 2006 • Commerce Group Inc /Ma • Fire, marine & casualty insurance • New York
Atlantic Holdings Corporation 4 Paragon Way, Freehold, New Jersey 07728 (732) 665-1100 Facsimile: (732) 761-0243 NASDAQ: NAHC CONFIDENTIALITY AND STANDSTILL AGREEMENT September 22, 2006 The Commerce Group, Inc. 211 Main Street Webster, MA 01570 Attention: Gerald Fels, Chief Executive Officer Ladies and Gentlemen: Each of National Atlantic Holdings Corp., a New Jersey corporation ("NAHC") and The Commerce Group, Inc., a Massachusetts corporation ("CGI"), may furnish certain confidential nonpublic information to the other party hereto in order to assist such other party in making an evaluation of a possible strategic transaction (a "Proposed Transaction") involving NAHC and CGI. Each party hereto, in consideration of the other party's agreement to furnish information to it (each party furnishing such information shall be hereinafter referred to, with respect to such information, as the "Disclosing Party" and each party receiving such information shall be hereinafter referred to, with res
