FERC approved Constellation's purchase of Calpine, which will create an even bigger IPP with nearly 60 GW around the country, with the biggest share of that in PJM.

As part of its review for the Constellation-Calpine merger, DOJ asked PJM for a major trove of market data as it looks into the region where the two firms' operations overlap the most.

FERC received several protests to Constellation's proposed purchase of Calpine, with PJM's Monitor arguing the companies need to make additional commitments to preserve competition in the RTO.