In an interview with CNN at Berkshire Hathaway’s annual meeting, Munger, who is Warren Buffett’s chief lieutenant, said he thinks the big banks are still too complicated and dangerous for the economy. But he doesn’t think a recently proposed bill by Senators Sherrod Brown and David Vitter, which has gotten praise from others who want to rein in big banks, is the answer.

“I think if you increase the capital requirements and let them do what they want, they will just get in trouble again,” says Munger.

Munger’s preferred prescription sounds like a stricter version of the Volcker Rule, which was meant to limit risky trading at the banks and was included in Dodd-Frank, but has yet to be implemented. He would force the banks to get out of their business of underwriting and trading derivatives, financial contracts that allow you to speculate, some say hedge, on commodities, interest rates, and other things. About a year ago, JPMorgan Chase (JPM) announced it had lost billions on a credit derivative hedge that had not worked out as expected.

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“I think banks should be more heavily regulated,” said Munger. “We shouldn’t have vast derivatives books in banks with insured deposits.”

In the past year, there has been a small stream of former top Wall Street executives, including former Citigroup (C) CEO Sandy Weill, who have said they are now for breaking up the banks. What’s notable about Munger, though, is that he is not only a financial services veteran. He is also one of the top executives of a company, Berkshire (BRKA), that is one of the largest investors in some of the nation’s largest banks, including Bank of America (BAC) and Wells Fargo (WFC).

Still, Munger seemed to suggest it was the role of the regulators, not big investors, to push for changes. Munger said he and Buffett make investment decisions based on the world they are in, not what they wished it to be, which is fair.

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But Munger also said he thought more regulations could make banks more profitable. By getting out of risky businesses, banks may end up giving back much less of their bull market gains in the down years. But if that’s true, then isn’t Munger’s fiduciary responsibility to Berkshire shareholders to push for change? If the change would make the banks more profitable, and presumably Berkshire’s investors more money, I think the answer is yes.

On Saturday at Berkshire’s annual meeting, Buffett said he thought the big banks were safer than they have been in years. But Berkshire doesn’t own derivative-heavy JPMorgan. Goldman Sachs (GS) has a derivatives business, but it has relatively few traditional bank deposits. The only Berkshire holding that seems to significantly break the Munger rule is Bank of America.

“You are asking me questions about my prescription for the country,” says Munger. “Well that would obviously be different from the prescription of our leading bankers.”

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