Steve Eisman was once described by Michael Lewis, author of "The Big Short," as a "fearless contrarian with a disdain for Wall Street who speaks his mind." However, the famed investor on Monday delivered a message on CNBC's "Fast Money" that should be music to the ears of major Wall Street firms.

Eisman, who now serves as a fund manager for Neuberger Berman, explained that investors should bet heavily on U.S. banks with the anticipation that the regulatory climate will become more favorable under President Trump. Eisman, who famously shorted the housing market before the financial crisis, believes that a confluence of positive factors could all serve to benefit the financial sector.

"We're long a whole bunch of banks and investment banks," Eisman said Monday on CNBC's "Fast Money," mentioning Citigroup specifically.

Eisman believes that major rollbacks of financial regulation are unlikely, but that an overall lighter touch will be positive for banks.

As rules loosen, and as higher rates improve the prospects for fixed income businesses, all types of financial companies are liable to do well, Eisman said.

Of course, a key component of Eisman's successful bet against the U.S. housing market came from shorting U.S. banks in 2007 as Wall Street's largest firms were entangled with bad high risk mortgage loans. While Eisman was initially met with skepticism when he decided to short the subprime market, the bet turned a massive profit.

As far as large market risks go, Eisman said that the reduced leverage in the financial system means that "there's no big short." In other words, solitary problems like the weakness currently seen in used auto prices will not become "a calamity" because such issues are no longer capable of taking down the entire financial sector.