PSI, IURC Staff, OUCC, PSI Industrial Group File Settlement Agreement On Cinergy, Duke Merger

PLAINFIELD, Ind., December 15, 2005 — PSI Energy Inc., the Indiana utility subsidiary of Cinergy Corp. (NYSE:CIN), today filed with state utility regulators a settlement agreement in the planned merger of Cinergy and Duke Energy (NYSE:DUK). The settlement is with the staff of the Indiana Utility Regulatory Commission, the Indiana Office of Utility Consumer Counselor, and the PSI Industrial Group. The settlement still needs Indiana Utility Regulatory Commission approval.

Some of the key elements of the agreement include:

• $40 million merger savings rate credit: PSI will credit to its Indiana electric customers $40 million over a year beginning 30 to 60 days following the close of the merger.
  
  
• $5 million for low-income energy assistance and clean coal technology: After the merger closes, PSI will make an annual contribution of $1 million for five years starting in 2006 and ending in 2010. PSI will distribute the funds to the state Low Income Home Energy Assistance Program and the Indiana Center for Coal Technology Research based at Purdue University.
  
  
• Service quality and customer service standards: PSI agreed to file quarterly performance reports with state regulators on customer service standards, such as the number and length of power outages as well as average speed of answer in the company’s customer Call Center. If benchmarks are not met, PSI will implement a service remediation plan as approved by state regulators.

“We've taken another step toward completing this merger, which will be good for both our customers and our investors over the long-term," said PSI President Kay Pashos. "In the short- term, the rate credit agreed to in the settlement will benefit customers in this period of rising fuel and energy costs, and the service quality benchmarks will provide assurance that PSI’s commitment to quality customer service will continue."

Also, as part of the agreement, PSI agreed not to pass on to customers any transaction costs associated with the merger and to discontinue in 2008 the recovery of costs from the company’s 1994 merger to create Cinergy. PSI is Indiana’s largest electric supplier, serving more than 750,000 customers in portions of 69 of Indiana’s 92 counties. It is an affiliate of Cinergy Corp., which has a balanced, integrated portfolio consisting of two core businesses: regulated operations and commercial businesses. Cinergy’s regulated public utilities in Ohio, Indiana, and Kentucky serve 1.5 million electric customers and about 500,000 gas customers. In addition, its Indiana regulated company owns 7,000 megawatts of generation. Cinergy’s competitive commercial businesses have 6,300 megawatts of generating capacity with a profitable balance of stable existing customer portfolios, new customer origination, marketing and trading, and industrial-site cogeneration. Cinergy’s integrated businesses make it a Midwest leader in providing both low-cost generation and reliable electric and gas service.

In May Cinergy announced its intention to merge with Duke Energy, a diversified energy company with a portfolio of natural gas and electric businesses, both regulated and unregulated, and an affiliated real estate company. Duke Energy supplies, delivers and processes energy for customers in the Americas. Headquartered in Charlotte, N.C., Duke Energy is a Fortune 500 company traded on the New York Stock Exchange under the symbol DUK. More information about the company is available on the Internet at: http://www.duke-energy.com.

Forward-Looking Statements This document includes statements that do not directly or exclusively relate to historical facts. Such statements are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements include statements regarding benefits of the proposed mergers and restructuring transactions, integration plans and expected synergies, anticipated future financial operating performance and results, including estimates of growth. These statements are based on the current expectations of management of Duke Energy and Cinergy. There are a number of risks and uncertainties that could cause actual results to differ materially from the forward-looking statements included in this document. For example, (1) the companies may be unable to obtain shareholder approvals required for the transaction; (2) the companies may be unable to obtain regulatory approvals required for the transaction, or required regulatory approvals may delay the transaction or result in the imposition of conditions that could have a material adverse effect on the combined company or cause the companies to abandon the transaction; (3) conditions to the closing of the transaction may not be satisfied; (4) problems may arise in successfully integrating the businesses of the companies, which may result in the combined company not operating as effectively and efficiently as expected; (5) the combined company may be unable to achieve cost-cutting synergies or it may take longer than expected to achieve those synergies; (6) the transaction may involve unexpected costs or unexpected liabilities, or the effects of purchase accounting may be different from the companies’ expectations; (7) the credit ratings of the combined company or its subsidiaries may be different from what the companies expect; (8) the businesses of the companies may suffer as a result of uncertainty surrounding the transaction; (9) the industry may be subject to future regulatory or legislative actions that could adversely affect the companies; and (10) the companies may be adversely affected by other economic, business and/or competitive factors. Additional factors that may affect the future results of Duke Energy and Cinergy are set forth in their respective filings with the Securities and Exchange Commission ("SEC"), which are available at www.duke- energy.com/investors and www.cinergy.com/investors, respectively. Duke Energy and Cinergy undertake no obligation to publicly update or revise any forward- looking statements, whether as a result of new information, future events or otherwise.

Additional Information and Where to Find It In connection with the proposed transaction, a registration statement of Duke Energy Holding Corp. (Registration No. 333-126318), which includes a preliminary prospectus and a preliminary joint proxy statement of Duke Energy and Cinergy, and other materials have been filed with the SEC and are publicly available. WE URGE INVESTORS TO READ THE DEFINITIVE JOINT PROXY STATEMENT- PROSPECTUS WHEN IT BECOMES AVAILABLE AND THESE OTHER MATERIALS CAREFULLY BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT DUKE ENERGY, CINERGY, DUKE ENERGY HOLDING CORP. AND THE PROPOSED TRANSACTION. Investors will be able to obtain free copies of the joint proxy statement-prospectus as well as other filed documents containing information about Duke Energy and Cinergy at http://www.sec.gov, the SEC’s Web site. Free copies of Duke Energy’s SEC filings are also available on Duke Energy’s Web site at: http://www.duke-energy.com/investors/, and free copies of Cinergy’s SEC filings are also available on Cinergy’s Web site at http://www.cinergy.com.

Participants in the Solicitation Duke Energy, Cinergy and their respective executive officers and directors may be deemed, under SEC rules, to be participants in the solicitation of proxies from Duke Energy’s or Cinergy’s stockholders with respect to the proposed transaction. Information regarding the officers and directors of Duke Energy is included in its definitive proxy statement for its 2005 annual meeting filed with the SEC on March 31, 2005. Information regarding the officers and directors of Cinergy is included in its definitive proxy statement for its 2005 annual meeting filed with the SEC on March 28, 2005. More detailed information regarding the identity of potential participants, and their direct or indirect interests, by securities, holdings or otherwise, will be set forth in the registration statement and proxy statement and other materials to be filed with the SEC in connection with the proposed transaction.