Potential buyers and sellers are also being deterred by the long wait for deal approvals by regulators, the experts said.

"Everyone's frozen in place until they know what the rules of the road are,” said Timothy Adams, CEO of the Institute of International Finance, an industry group that represents about 400 members from more than 60 countries.

Adams expects deals to be stalled through 2026 as the U.S. implements standards that were agreed by the Basel Committee on Banking Supervision after the 2008 financial crisis but then took years to be finalized. Global regulators agreed to give banks a transition period to meet the new requirements and set the beginning of 2025 as the target for full implementation.

At the same time, banks are also waiting to fund a potential increase in capital requirements signaled by the Federal Reserve's vice chair for supervision, Michael Barr, in the aftermath of a U.S. regional banking crisis this year.

The uncertainty over capital rules has created a "chilling effect" that could put a lid on mergers, while rising interest rates and a looming economic downturn could also damp activity, Adams said.

'UNHEALTHY ENVIRONMENT'

Still, banks in distress may be forced to sell. Deals involving banks either in receivership or under stress rose to $23.2 billion in the first quarter to the highest since 2019, according to data from Dealogic. That compares to $3.9 billion in bank deals for non-stressed institutions, the lowest seen over the first half of a year since 2010.

“We have an unhealthy environment for regional bank mergers,” said Meg Tahyar, head of the financial institutions group at law firm Davis Polk, citing the slow pace of deal approvals in recent years.

"Instead of evaluating mergers based on competition and the needs of the community, political factors have become too important," she said. "There is also too much uncertainty about regulatory changes that will impact pricing.”

While U.S. Treasury Secretary Janet Yellen has signaled regulators will likely be open to more mergers among regional banks, recent delays have discouraged merger discussions.

In May, Canada's Toronto-Dominion Bank called off its $13.4 billion takeover of First Horizon after failing to get approval from regulators more than a year after the deal was announced.

“We do not see many deals happening in the short term due to factors such as low stock prices, uncertainty around regulatory approvals and the potential for higher capital requirements," said Tim Johnson, global financial services leader for deal advisory at KPMG. Still, "the long term trend of consolidation is inevitable.”

Once capital requirements are clarified in the U.S., transactions could surge again for banks close to the threshold of $100 billion in assets. These banks will be subject to stricter rules similar to those applied to the largest banks and will come under pressure to combine so they can compete with the biggest institutions.

Regional banks will "have incentives to merge and reach larger scale since they will be subject to more regulatory scrutiny and capital,” Johnson said.