The timing isn’t a coincidence. Many of the deals wouldn’t have been possible before Trump, because the top banking agencies under Obama followed an informal policy to stop or discourage dozens of banks from expanding while they dealt with compliance issues, according to people with knowledge of the matter.

That era’s shadow constraints most often stemmed from compliance issues related to consumer-protection and anti-money-laundering rules, rather than concerns about financial stability, the people said, asking not to be identified discussing confidential information.

The anti-expansionary attitude meant growth plans were derailed even in some situations where the Fed and OCC didn’t usually have formal approval powers, like when a financial holding company buys non-bank assets, according to people familiar with conversations between banks and their supervisors.

Representatives for most of the banks declined to comment, although spokesmen for SunTrust and BB&T said the two companies are “fully engaged” with regulators in the review process for their merger, and encouraged by “positive comments” they’ve received.

The OCC declined to comment for this story, and a Fed spokesman said the agency’s criteria for reviewing mergers and new branches and markets is clear and publicly available. “While those criteria have not substantively changed in recent years, the financial conditions and risk-management capabilities of many firms have improved and are taken into consideration,” the spokesman, Eric Kollig, said.

JPMorgan Branches
Last year, in one of the first signs of a reversal, Trump-appointed regulators green-lit JPMorgan’s plans to open branches in new states as part of an ambitious national expansion. For years leading up to that about-face, regulators had used their discretion to stifle the bank’s growth.

To be sure, the increase in activity is still a far cry from the spree of mergers in the 1990s that led to the formation of global titans such as Citigroup Inc. and Bank of America.

But the shift is dramatic compared with the first years after the financial crisis. Around 2012, for instance, JPMorgan attempted to set up banking operations in Ghana and Kenya as part of a push to foster more lucrative relationships with governments and multinationals. The plans were derailed when Tom Curry, then-comptroller of the currency, said the move would be too risky, according to people with knowledge of the matter.

Later, JPMorgan executives mapped out a strategy to boost revenue by opening branches in new markets such as Washington, D.C., where the biggest U.S. bank already offered credit cards and mortgages. The OCC told the bank that plan also carried too many risks, the people said. The bank was also quietly prohibited from engaging in mergers and acquisitions, one of the people said.

Joe Evangelisti, a JPMorgan spokesman, declined to comment.