EX-99.1 2 ex_99-1.txt JOINT FILING AGREEMENT EXHIBIT 99.1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13D filed herewith (and any amendments thereto), relating to the Common Stock, no par value, of Duquesne Light Holdings, Inc., is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, on behalf of each such person. Dated: July 17, 2006 DUET INVESTMENT HOLDINGS LIMITED By: /s/ Bruce K. Berry -------------------------- Name: Bruce K. Berry Title: Chief Financial Officer DIVERSIFIED UTILITY AND ENERGY TRUST NO. 1 (DUET1) By: /s/ Bruce K. Berry -------------------------- Name: Bruce K. Berry Title: Chief Financial Officer DIVERSIFIED UTILITY AND ENERGY TRUST NO. 2 (DUET2) By: /s/ Bruce K. Berry -------------------------- Name: Bruce K. Berry Title: Chief Financial Officer AMPCI MACQUARIE INFRASTRUCTURE MANAGEMENT NO 1 LIMITED (RE1) By: /s/ Bruce K. Berry -------------------------- Name: Bruce K. Berry Title: Chief Financial Officer AMPCI MACQUARIE INFRASTRUCTURE MANAGEMENT NO 2 LIMITED (RE2) By: /s/ Bruce K. Berry -------------------------- Name: Bruce K. Berry Title: Chief Financial Officer