“We were just deluged,” Mr. Ehrlich said, with “tens of billions” coming in without the need to call around and pitch services. “We were working very hard to accommodate clients, and trying at the same time to make sure we didn’t screw anything up in processing record volumes.”

Even for the strongest financial institutions, banking is not an easy business to be in right now and it could well get worse. And once the current crisis is over, banks in both the United States and Europe will be subject to more regulation and tighter capital requirements, a sure-fire recipe for lower profits.

Even before a new framework is sorted out, leading European banks  like the surviving American giants Bank of America, Citigroup, Wells Fargo and JPMorgan Chase  are preparing to take advantage of their more diversified stature.

Klaus-Peter Müller, chairman of Commerzbank and the Association of German Banks, said the universal bank model was looking better by the day, thanks to the multiple pillars that support its business. “Usually when one pillar suffers, the others do better,” Mr. Müller said. “Seldom do all sectors of a universal bank do badly.”

Barclays, the British banking giant, acquired the North American investment banking and capital markets units of Lehman, along with its New York offices, for $1.75 billion late last month.

That is far less than such businesses were worth only a few weeks ago.

On Wednesday, the French bank BNP Paribas completed its acquisition of Bank of America’s prime brokerage unit, giving it new entree in a business long dominated by the likes of JPMorgan, Morgan Stanley and Goldman Sachs.

“People are now coming to us,” said BNP’s chief executive, Baudouin Prot.

And if they are not coming, European banks are not shy about going after them. Deutsche Bank’s poaching of prime brokerage clients from Morgan Stanley and Goldman Sachs was forceful enough that it got a polite but firm word from regulators, an executive with the bank said. With the crisis this bad, Deutsche Bank was told, we need you to ease off.