Exelon Corp., parent company of Peco Energy Co. and one of the nation's largest power generators, said today that its fourth-quarter profit fell 18 percent on weak electrical demand.

After the Chicago company's stock sank - at midafternoon, it was down 2.06 percent to $47.06 - Exelon chief executive John W. Rowe cast the earnings report as "nothing but good news" that "bodes well" for the current year.

Exelon made $581 million, or 88 cents per share, for the quarter ended Dec. 31 compared with profit of $707 million, or $1.07 per share, in the year-ago quarter. Revenue fell to $4.12 billion from $4.49 billion a year ago.

In a conference call with analysts, Rowe said the earnings fell within the company's previous guidance and he reaffirmed projections that the company would earn $3.60 to $4 a share this year.

"The fourth quarter makes us feel better, not worse, about 2010," Rowe said.

Exelon and other power generators have been hurt by declining electricity usage caused by the recession. Consumption also fell because the mild summer weather, though Rowe said Exelon "had a little better luck on weather" in the last quarter.

For all of 2009, Exelon's earnings were flat at $2.7 billion. Earnings per share were $4.09 for the year compared with $4.13 in 2008. Without charges and gains, Exelon made $4.12 per share for the year compared with $4.20 per share in 2008.

The company said quarterly earnings at its Peco subsidiary were down $2 million, to $78 million, and that the number of residential electric customers declined by 0.4 percent from last year.

Rowe said Exelon was also working with regional grid operator PJM Interconnection Inc., which has identified "potential reliability impacts" of Exelon's announcement to close the Cromby Generating Station in Phoenixville next year and to retire two coal-fired generators at the Eddystone Generating Station in Chester.

PJM could potentially order Exelon to keep some or all of the plants' units operating if their absence would imbalance power flows on the grid.