If you listened closely this week, you could hear the champagne corks popping all over lower Manhattan. The big banks just dropped their third-quarter earnings, and to put it mildly, it was a blowout. After a spring frozen by economic uncertainty, the dealmaking machine has roared back to life, showering Wall Street with profits.

JPMorgan Chase and Goldman Sachs, the titans of the industry, posted results that shattered analyst expectations. JPMorgan saw its investment banking revenue climb by a healthy 17%, while its trading desks had a stellar quarter, jumping 25%. Goldman Sachs had an even more spectacular run, with its investment banking division’s revenue soaring an incredible 42% from a year ago.

The party wasn’t limited to the usual suspects. Wells Fargo and Citigroup also posted muscular profits, driven by the same boom. Wells Fargo, which recently raised its own profitability targets, highlighted its role in the massive $72 billion railway merger between Union Pacific and Norfolk Southern—a perfect example of the kind of mega-deals fueling this bonanza.

What’s Fueling the Frenzy?

So, what changed? It seems corporate America decided to shake off its anxiety. After months of sitting on the sidelines, spooked by shifting trade policies and tariffs, big companies have unleashed a torrent of activity. The summer and fall have seen a boom in public offerings, corporate bond sales, and the kind of large-scale mergers that generate massive fees for the banks that advise them.

There’s also a sense that the regulatory environment in Washington may be getting a bit more comfortable, adding another tailwind. This combination of pent-up demand and a clearer path forward has created a nearly perfect environment for investment banking and trading profits.

A Note of Caution from the Hosts

Here’s the interesting part. Even as the bank CEOs were delivering these fantastic results, their commentary was laced with caution. You could almost hear them telling their teams not to get too comfortable.

JPMorgan’s chief executive pointed to a resilient U.S. economy but was quick to list “significant risks” on the horizon, including trade uncertainty, worsening geopolitical conditions, and high government deficits. His counterparts at Goldman and Wells echoed the sentiment, stressing that while things are good now, conditions can change in a heartbeat.

It’s the classic mantra of “hope for the best, but prepare for anything.” The people running these firms know that the current boom is happening against a backdrop of serious global and domestic challenges. The stock market seemed to notice this paradox, too; while Wells Fargo and Citi shares jumped on the news, JPMorgan and Goldman actually dipped slightly, perhaps a sign that investors wonder if this is as good as it gets.

For now, the party rages on. The question is whether it’s a sustainable rally or just a fleeting sugar rush before the inevitable hangover kicks in.