Why The Nation’s Biggest Banks Are Even Bigger Than You Thought: Already, the biggest banks in the U.S. are huge. The largest 0.2 percent of institutions — just 12 mega-banks — control 69 percent of total bank assets. The 20 biggest banks hold assets equal to 84.5 percent of the nation’s entire economic output. And if the U.S. accounted for bank assets (and risk) in the [...]/p