The pressure seems to be Credit Suisse CEO Tidjane Thiam, and perhaps other European bank executives, like DB’s John Cryan, Barclays’ James Staley, HSBC’s Stuart Gulliver and UBS’ Sergio Ermotti,  to consider more radical ways to reduce their financial commitments to some of their investment banking operations.

After all, Wall Street banks seem to have won most of the battle for M&A supremacy, while the regulators keep demanding that all banks put up more capital against these activities.

Mr. Thiam told The Financial Times that Credit Suisse is talking to a rival about pooling costs, which suggests “this is just the beginning.” And it’s easy to see where this deliberation might lead. The idea of merging investment banks may sound so last century and more than a little stupid. After all, Credit Suisse paid $11.5 billion for the NY-based Donaldson, Lufkin & Jenrette in 2000, only to see the firm’s rainmakers depart and their combined market share fail to materialize. It later wrote off the value of the acquisition.

But many of the European banks that bulked up over the last few decades on Wall Street now stand at an existential crossroads. They are gazing at a future in which these businesses, even if they are able to make a profit, will probably struggle to cover their costs of capital in the foreseeable future. This puts them at a competitive disadvantage in wooing clients and retaining talent relative to the American companies. It’s an ugly cycle.

As the head of one U.S. bank told the NYTimes last week: “It’s over — the Americans won.” The top slots in the rankings for core investment banking products are all held by some combination of Goldman Sachs, Morgan Stanley, JPMorgan Chase, Citigroup and BofA Merrill Lynch. The picture is broadly similar in the arenas of stock and bond market trading.

One way to be more efficient would be for Deutsche and Credit Suisse to crunch their United States businesses together. They would also get bigger scale. If the banks were able to maintain their respective market share positions under one roof, they would vault up the rankings. A Credit Suisse-Deutsche Bank duo, for instance, would have challenged JPMorgan as the leading underwriter of global equity and equity-linked securities, raising $47 billion for clients, year to date. And it might figure as a top five merger adviser.

Merging would undoubtedly be messy, and winning regulatory approval for such a deal would take finesse from the banks involved.

Who knows? One day, maybe.