US and European stocks have fallen sharply after President Barack Obama proposed significant limits on how banks can operate.
The main US share index, the Dow Jones, fell more than 200 points or 2% as the president delivered his speech, with banking stocks most affected.
The Dow subsequently ended the day down 213 points or 2% at 10,390.
In Europe, the UK's main FTSE 100 index ended down 1.6%, with banks again leading the declines.
Banks JP Morgan Chase and Bank of America were two of the biggest fallers on the Dow, losing 6.6% and 6.2% respectively.
On the FTSE 100, Royal Bank of Scotland posted the biggest drop, ending down 7%, while Barclays lost 5.9%.
Under the plans outlined by President Obama, he wants to limit the size of banks and introduce restrictions on riskier trading.
His proposals include a ban on retail banks using their own money in investments - known as proprietary trading. Instead, banks would be limited to investing their customers' funds.
Scott Marcouiller, senior equity market strategist at Wells Fargo Advisors in St Louis, said: "In the midst of the uncertainty of everyone trying to sort out exactly what [Obama] said, exactly how it will be implemented, and whether it has a chance of getting through Congress, the natural response is to sell now and ask questions later."