[新闻背景]The head of America’s biggest bank has apologized for risky dealings that incurred a $2 billion loss - an unwelcome echo of the 2008 financial crisis that plunged the United States into the deepest recession of the post-World War II era. JP Morgan Chase executive Jamie Dimon faced questioning from U.S. senators.

It was four years ago that a cascading failure of America’s biggest financial institutions triggered massive federal bailouts and legislation designed to curb risk-taking and, it was hoped, avoid another economic meltdown.

On Capitol Hill, news of substantial new losses at JP Morgan Chase has renewed debate on the efficacy of those reforms.

Chief Executive Officer Jamie Dimon expressed contrition to the Senate Banking Committee.

"We have let a lot of people down, and we are very sorry for it," he said.

Dimon explained that a new investment model designed to reduce risky financial dealings actually increased risk exposure. He said the model has been abandoned in favor of older, time-tested ways of doing business.

On a brighter note, Dimon said the losses are only a tiny fraction of JP Morgan Chase’s total holdings, which exceed $1 trillion. And he offered this overall assessment of America’s private banking sector. "I do think that since the [2008 financial] crisis - and you should have comfort in this - banks are better capitalized," he said. "They have more liquidity. There is more transparency.

America’s free-enterprise system thrives on risk-taking. But how best to manage that risk is a continuing concern for lawmakers, as the Banking Committee’s chairman, Senator Tim Johnson noted.

"While risk cannot be eliminated from our economy, we can and must demand that banks take risk management seriously, and maintain strong controls," he said.

The ranking Republican on the committee, Senator Richard Shelby, stressed private banks’ vital role in capitalism.

"Banks take risks because that is what they do. Usually those risks are beneficial. They enable Americans to buy homes, attend college, and save for retirement," he said.

But Shelby added that the federal government does have an interest in how banks conduct business.

"Normally, it is not - and I believe it should not be - the role of Congress to second-guess decisions by private sector businesses," he said. "However, because the federal government guarantees bank deposits, this committee has a responsibility to ensure that banks do not unnecessarily put taxpayers at risk.

Implementation of federal financial reforms is ongoing. JP Morgan Chase’s Jamie Dimon was asked if those reforms are making America’s financial system safer. His response: "I do not know."