Neither company gave reasons why the proposal failed, but the two companies disclosed in shareholder reports last month the talks hit an obstacle over governance structure and value-related issues.

Such a merger would have combined the resources of Florida's largest producer of electricity, which generates annual revenue in excess of $7 billion and serves about 3.9 million electricity consumers, with a New Orleans-based energy company that produces annual revenue of about $10 billion and provides electricity to about 2.6 million customers in Arkansas, Louisiana, Mississippi and Texas.

Under terms of the agreement, neither company pays a termination fee unless either of the parties enters into future merger talks within the next nine months with any other company. Each company is responsible for its respective merger costs. All regulatory filings related to the merger also will be withdrawn.