A key banking executive in the United States has apologized to Congress for financial trading mistakes that cost his company $2 billion.

Wall Street titan Jamie Dimon, chief executive of the JPMorgan Chase investment banking firm, told the Senate banking committee Wednesday that its managers, starting late last year, mismanaged a series of investments. He said the trades were “poorly conceived and vetted.”

Dimon said the company was sorry for the losses, which affected JPMorgan shareholders, not the company's business partners or U.S. taxpayers.

“This portfolio morphed into something that, rather than protect the firm, created new and potentially larger risks. As a result, we have let a lot of people down, and we are very sorry for it.”

Dimon said the mistakes were “embarrassing,” but that the company had taken steps to improve its performance.

“Importantly, our team has made real progress in aggressively analyzing, managing and reducing our risk going forward. While this does not reduce the losses already incurred and does not preclude future losses, it does reduce the probability and magnitude of future losses.”

Before Dimon testified, at least a dozen protesters chanted “Stop foreclosures now,” referring to the millions of Americans who have lost their homes when they could no longer make their monthly loan payments to banks, often because they had lost their jobs in the country's economic downturn. Security officials escorted them out of the hearing room.