Exelon

(EXC) - Get Report

is reportedly in advanced talks to buy New Jersey's largest utility group,

Public Service Enterprise Group

(PEG) - Get Report

.

According to

The Wall Street Journal's

online edition on Friday, the deal, which is estimated to be worth roughly $12 billion, if consummated, would create one of the largest electric companies in the U.S., with service areas that would spread across Illinois and the Mid-Atlantic states.

Exelon, a Chicago-based public utility holding company, would also assume PSE&G's nearly $13 billion in long-term debt, giving the deal a total enterprise value of about $25 billion.

The talks reportedly were at a sensitive place and could still fall apart; but unnamed sources cited by the newspaper said that an announcement of the deal could come as early as next week.

Shares in PSE&G were recently up $1.41, or 2.9% , to $48.68 in after-hours trade; they closed the regular session up $1.66, or 3.6%, to $47.27. Exelon shares were recently up 8 cents in after the bell, or 0.1%, to $41.94. They ended the day down 74 cents, or 1.7%, to $41.86