Power company Constellation Energy Group Inc. swung to a quarterly profit amid big gains from a recent sale of half its nuclear business as well as a 45 percent decline in costs, however, revenue missed Wall Street estimates by a large margin.

The company, an energy products and services provider, also reaffirmed its 2010 earnings guidance of $3.05 to $3.45 per share, compared with analysts' view of $3.36 a share.

The company reported its fourth quarter net income applicable to common shareholders as $4.42 billion, or $21.96 a share, in contrast with a loss of $1.41 billion, or $7.75 a share, previous year. The latest fourth quarter includes a gain of about $4.5 billion from the sale of its stake in its nuclear unit to Electricite de France.

Its profit excluding items registered for 30 cents a share and quarterly revenue reportedly lowered 30 percent at $3.40 billion.

However, analysts surveyed by Thomson Reuters I/B/E/S on average estimated the company to report a profit of 24 cents a share, before items, on revenue of $4.35 billion.

Shares of the company closed at $34.58 Friday on the New York Stock Exchange.