Stock markets have fallen sharply in response to far-reaching plans by Barack Obama to curb¹ the activities of the biggest US banks.

奥巴马控制美国各大银行财政行为的长远举措出台之后，股票市场急剧下滑。

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The effects of US banking plans will be felt around the world

The Dow Jones closed down 2%, its worst fall since October, while Japan's Nikkei日经指数 was down early on Friday.

Shares in major US banks Goldman Sachs, JP Morgan and Bank of America all fell.

Mr Obama - who said he was "ready for a fight" with banks - plans to limit the size of banks and impose restrictions³ on risky⁴ trading.

"Never again will the American taxpayer⁵ be held hostage by banks that are too big to fail," Mr Obama said.

Limiting risk taking

"While the financial system is far stronger today than it was one year ago, it is still operating under the exact same rules that led to its near collapse," Mr Obama said.

His proposals may mean that some of the biggest US banks have to be broken up.

They also include a ban on retail⁶ banks using their own money in investments - known as proprietary⁷ trading自营交易. Instead, banks would be limited to investing their customers' funds.

That attitude brought an immediate⁸ reaction from the markets.

Investment banking giant Goldman Sachs lost more than 4% despite announcing a sharp increase in profits. Bank of America fell 6.2% and shares in JP Morgan Chase were down 6.6%.

"Banking reforms do not come bigger than those proposed by President Obama," the BBC's business editor Robert Peston said.