Mr. Kashkari’s proposal — called the Minneapolis Plan — would most likely pressure banks to break apart because the high cost of holding so much capital would mean it would no longer make sense to stay so large.
Such a breakup has not happened naturally since the financial crisis. While some big banks have gotten smaller, a great deal of lending and market-making activity is still concentrated in hands of a few Wall Street banks. And with that continued concentration comes risk of another bailout, he said.
By Mr. Kashkari’s calculation, the financial regulation since 2008 has reduced the chances of another government banking bailout to only 67 percent from 84 percent before the crisis.
His proposal would reduce that risk to 9 percent, he said, by requiring banks to hold much more capital than the current levels.
“I don’t want people to have a false sense of security that we have solved too-big-to-fail,” Mr. Kashkari said during the breakfast discussion on Wednesday.