On most cable newscasts, the people who are writing new financial regulations are called congressmen. But on “The Dylan Ratigan Show” on MSNBC, some are called “banksters.”

That term, a twist on gangsters, tells viewers a lot about Mr. Ratigan, a financial news apostate who has transformed himself into an outspoken opponent of too-big-to-fail banks and the politicians whom he calls their servants. In the recent fight over financial reform, he lent a megaphone to people who wanted an end to “too big to fail,” and he called on viewers to lobby the Senators in his imaginary Bankster Party.

All this from a man who, until recently, hosted a stock-picking show on CNBC, the cable personification of Wall Street. Now Mr. Ratigan, who labels himself a taxpayer advocate, rails against the “vampire” banks who “have assumed control of our government.”

“It’s like being the guy who was running the casino, and then having an awakening and realizing that the casino is what’s killing the country,” Mr. Ratigan said in an interview last week.