NEW YORK ( TheStreet) -- Duke Energy ( DUK) is in advanced talks to buy its peer Progress Energy ( PGN), in a deal worth more than $13 billion, which would mark another significant step in the long-awaited consolidation of the U.S. power sector and create the country's largest utility.People familiar with the matter said that the deal between Duke and Progress, which could be announced as soon as Monday, would be a stock-based transaction. Progress' market value at the end of last week was $13.1 billion, while Duke is worth $23.6 billion. Those people added that they believed the deal would involve a modest premium but the price could not be determined. Deals in the utility sector are often billed as mergers, rather than takeovers involving a control premium. While the companies are targeting an announcement before the markets open on Monday, people familiar with the matter said that final details had yet to be agreed, which means the deal announcement could be pushed back or talks could be derailed. > > Bull or Bear? Vote in Our Poll Duke Energy and Progress Energy both declined to comment. The two companies have long been considered a good match in the U.S. utility sector. Both are based in North Carolina, offering substantial scope for cost savings as part of a combination. Moreover, say industry experts, the sector is one that increasingly rewards greater scale. Larger companies have an advantage in terms of capital raising and in spreading the risk of projects, such as building nuclear facilities, over a bigger balance sheet. Progress has about $10 billion in annual revenue and more than 22,000 megawatts of generation capacity. Through its two utilities, Progress serves about 3.1 million customers in North and South Carolina and Florida. Duke supplies about 4 million customers, using 35,000 megawatts of electric generating capacity in the Carolinas and the Midwest as well natural gas distribution services in Ohio and Kentucky. Duke has recently found itself in hot water, after claims that the company's Indiana unit was improperly close to the state's main regulator and forced the resignation of a number of Duke executives.