NEW YORK ( TheStreet) -- Big banks are likely to break themselves up to appease investors, even though a wholesale government-mandated breakup isn't going to happen, Keefe Bruyette & Woods ( KBW) CEO Thomas Michaud argued Wednesday. "I think the market's telling us that it has to happen. If you look at the six universal banks in the country and you pull out Wells Fargo ( WFC), the remaining five trade at 65% of tangible book value," Michaud said during a panel discussion at a community banking conference hosted by the financial services-focused investment bank. Referring to Morgan Stanley ( MS), Goldman Sachs ( GS), JPMorgan Chase ( JPM), Citigroup ( C) and Bank of America ( BAC), Michaud said "these are the biggest banks in the nation and I think that's unsustainable. Either the banks' performance has to get better or if book value's real they're going to have to realize it on behalf of shareholders." Michaud agreed with fellow panelist and KBW Washington analyst Brian Gardner that the big banks will slowly be scaled back over time rather than in one sweeping effort. "This is not an AT&T moment. This isn't Standard Oil," Gardner said. "You're not going to turn around a year from now and see one of the megabanks broken up into six baby megabanks. That's not going to happen." However, Gardner pointed to rules forcing big banks to hold increasingly large capital buffers and "a movement among the regulators to really come down hard on the largest banks." Jumping off of these remarks, Michaud pointed to reports Morgan Stanley may look to sell off part of its commodities division, saying, "I think you'll see things like that, and you'll see they'll continue to hone the companies, but I think they're too big and I think there's going to continue to be deleveraging." Alluding to his audience of smaller bank CEOs, he added, "I think that's going to be an opportunity for a lot of people in this room." Michaud then cited recent research his company has done to commemorate its 50 year anniversary, noting that in 1962 "Bank of America was the largest in the nation and had 5% of the nation's assets. Today, JPMorgan has 17% of the nation's assets. That's just too big." There has been a steady drumbeat of calls for breaking up the largest banks ever since the 2008 financial crisis. However, the topic picked up steam recently when ex-Citigroup chief Sandy Weill, who may have done more than any living person to popularize the big bank model, said he no longer thinks it makes sense. -- Written by Dan Freed in New York. Follow this writer on Twitter.