SunTrust

Some have suggested the BB&T-SunTrust deal could spur similar ones, but prolonged M&A growth is hardly a sure thing in this political environment.

“The board's record of summarily approving mergers raises doubts about whether it will serve as a meaningful check on this consolidation that creates a new too big to fail bank,” Sen. Elizabeth Warren said in a letter to the Fed.

M&A editor Paul Davis explores the practical and political implications of the proposed merger between BB&T and SunTrust.

The stars aligned for the two longtime rivals to join forces, and some observers speculate that other regional banks will need to strike similar partnerships if they hope to remain competitive. But others say such deals are rare because they're hard to pull off.

The combined bank will move into a more demanding supervisory class under the Fed’s regime, but analysts also see a regulatory upside from the deal.