Exelon Corp., on Wednesday moved a step closer to acquiring Constellation Energy Group Inc. after the U.S. Justice Department approved the proposed merger on the condition that Exelon sell three power plants in Maryland.

The justice department said the combination of Exelon, parent company of Peco Energy Co., and Constellation, the parent company of Baltimore Gas & Electric Co., could manipulate mid-Atlantic wholesale power prices. The sale of the three plants would resolve the anticompetitive claims.

Exelon had already agreed to sell the three plants to satisfy the market monitor of PJM Interconnection L.L.C., the regional power pool. Maryland's governor also approved the divestiture this month. The merger still requires the approval of some federal and Maryland regulators.    - Andrew Maykuth