Progress Energy has agreed to settle lawsuits that aimed to block its merger with Duke Energy by adding details to a proxy statement before an Aug. 23 shareholder vote on the deal.

The agreement will settle nine state class-action lawsuits, consolidated into one, that claimed Progress shareholders wouldn't get a good deal with the merger. The suits named Duke as a co-defendant.

The settlement, which Progress outlined in a securities filing Friday, does not change the merger terms. It has to be approved by Superior Court judge.

The agreement does not affect a similar federal lawsuit, "but we do not expect the federal suit to affect the schedule for the shareholder vote," Progress spokesman Mike Hughes said.

Progress and Duke will also pay up to $550,000 in legal fees for the plaintiffs.

"The real issue for us, the heart of our claim, was that shareholders were being denied material information that would allow them to cast a fully knowledgeable vote," said Jason Cowart, the New York attorney serving as lead counsel for the plaintiffs. "We think these disclosures, regardless of the merits of the deal, allow shareholders to cast fully informed votes."

Progress, in its Securities and Exchange Commission filing, said it agreed to the settlement "solely to eliminate the burden and expense of further litigation, to put the claims that were or could have been asserted to rest, and to avoid any possible delay to the closing of the merger that might arise from further litigation."

Duke and Progress announced their intended merger in January, creating the largest U.S. utility. Federal and state regulators still have to sign off; that's expected by the end of the year.

Language to be inserted in the Progress proxy statement includes brief descriptions of:

The Progress board's discussion of how Carolinas regulators would view a merger with Duke compared to a combination with "Company A," understood to be Virginia-based Dominion Resources.

The board found it likely regulators would prefer Duke as a partner because of the companies' Carolinas customer base, potential nuclear sites and likely cost savings.

Progress CEO Bill Johnson's telling his board the transaction "would be structured similar to a merger of equals," rather than as an acquisition.

Financial analyses of premiums paid in similar utility mergers, the likely effect of the deal on the value of Duke stock that Progress shareholders would receive, and potential dividend increases.

Under the deal, Progress shareholders will get 2.6125 shares of Duke stock for each share of Progress common stock. The transaction price represented a 6.4 percent premium over the 20 trading days before the merger was announced, compared to the 4.9 percent average of other mergers analyzed.

The potential risks of Duke's troubled Edwardsport power plant project in Indiana, which has been plagued by cost overruns, conflict-of-interest charges involving Duke and Indiana regulators, and claims of mismanagement.