**US President Barack Obama has proposed limits to the size of banks to try to prevent future financial crises.**His proposals also include limits on the amount of risk banks can take, and banning retail banks from trading from their own money.
“Never again will the American taxpayer be held hostage by banks that are too big to fail,” Mr Obama said.
He recently announced a $117bn (£72bn) levy on banks to recoup money US taxpayers spent bailing out the banks.
US stocks - especially banks - fell sharply as Mr Obama announced the rules.
The moves follow popular anger at financial institutions, who have been paying large bonuses to staff even as they accepted government bail-outs to keep them going.
The tax will claw back some of the losses from a $700bn taxpayer bail-out of US banks known as the Troubled Asset Relief Program (Tarp).
It was drawn up in the midst of the financial crisis in 2008, following the collapse of US investment bank Lehman Brothers and rescue of insurance giant American International Group (AIG).
Mr Obama’ s proposals appear to be a return to the principles underlying the Glass-Steagall Act.
That law - from the 1930s - separated commercial and investment banking and was eventually abolished in 1999 under President Bill Clinton.
Mr Clinton’s financial secretary at the time, Robert Rubin, previously worked at Goldman Sachs and went on to be an advisor to Citigroup until last year.