Another top executive from Progress Energy is leaving in the wake of the Raleigh-based power company's troubled merger with Charlotte's Duke Energy.

Duke said today that Vincent Dolan, 57, will step down by the end of this year. That would make Dolan, who will have worked for the Raleigh utility more than a quarter-century, the fifth high-level executive to leave what is now the nation's biggest electric utility in the wake of the $32 billion merger.

No reason was given for Dolan's planned departure. But it's no secret that Duke was disappointed in the way Progress handled its Florida operations, which Dolan had overseen since 2009. Duke officials told the N.C. Utilities Commission in public hearings last month that they had serious concerns about the Progress-Duke merger on account of soaring nuclear costs in Florida, Progress Energy's biggest service area.

In its announcement, Duke lauded Dolan as "an exemplary leader and a tireless advocate for Florida customers."