HSBC's chief executive apologised today for shameful and embarrassing mistakes made on anti-money laundering controls.
This comes as the bank sets aside $2 billion to cover the cost of US investigations and compensate UK customers for mis-selling.
Europe's biggest bank reported a 3% dip in underlying profit and said it had made a provision of $700m to cover "law enforcement and regulatory matters".
A US Senate report this month criticised HSBC for letting clients shift funds from dangerous and secretive countries.
The report criticised a "pervasively polluted" culture at the bank and said that HSBC's Mexican operations had moved $7 billion into the bank's US operations between 2007 and 2008.
"What happened in Mexico and the US is shameful, it's embarrassing, it's very painful for all of us in the firm," chief executive Stuart Gulliver told reporters on a conference call, adding that the eventual costs could be "significantly higher".
"We apologise for our past mistakes in relation to anti-money laundering controls, and it is a priority for senior management to build on steps already taken to manage risk and ensure compliance more effectively," Mr Gulliver said.
Analysts had said the US investigations could result in a fine of about $1 billion. HSBC is also one of several banks being investigated in a global interest rate rigging scandal that has rocked the sector.
Mr Gulliver said it had submitted information to regulators but it was far too early to say what the outcome would be or to estimate the potential cost for the bank.
HSBC has set aside $1.3 billion to compensate UK customers for mis-selling loan insurance to individuals and interest rate hedging products to small businesses.
The bank reported a pretax profit of $12.7 billion for the six months to the end of June, up 11% on the year and above an average analyst forecast of $12.5 billion. But underlying profit, stripping out gains from US assets sales and losses on the value of its own debt, was down 3% on the year to $10.6 billion.