Gasparino expanded on that analysis Tuesday. He claimed the financial industry "was not expecting" a presidential candidate to adopt the kind of aggressive approach towards Wall Street. Further, Gasparino suggested that even though O'Malley is polling far behind Clinton, there are fears his message could resonate and push Clinton "to the left" on Wall Street.

"Right now people on Wall Street are talking about Martin O’Malley. Now does he have a chance to win? I’m not a political guy, it would seem like odds are low based on everything that I know," Gasparino said, later adding, "What they're really worried about is not that he's going to win. It’s that he's going to force [Clinton] so far to the left with that resonating message."

Gasparino said Wall Street fears this O'Malley effect could stop Clinton from doing "some of the things they want her to do like water down Dodd-Frank."

"They really think that if she gets in there, that if Hillary Clinton gets in there, that Dodd-Frank will be watered down to the point where they can do proprietary trading using their own capital to trade which is outlawed right now. And various aspects of Dodd-Frank will be freed up so the banks can go back to making a lot of money," Gasparino explained. "Not that they don't make a lot of money now, but even more money, Clinton-era money."

Recently, the CEO of Goldman Sachs let his employees know that he’d be just fine with either [Jeb] Bush or [Hillary] Clinton. I bet he would," O'Malley said.

"Well, I’ve got news for the bullies of Wall Street: The presidency is not a crown to be passed back and forth by you between two royal families. It is a sacred trust, to be earned from the American people, and exercised on behalf of the people of these United States."

O'Malley's populist ire wasn't limited to Goldman Sachs. In his announcement speech, he focused on income inequality, which he described as a situation wherein "Main Street struggles, while Wall Street soars."

He accused the "privileged and the powerful" of having been "the ones who turned our economy upside down in the first place" and lamented the fact "not a single Wall Street CEO was convicted to a crime related to the 2008 economic meltdown."