HSBC is preparing to apologize to the U.S. Senate for failing to prevent potential money laundering activities from taking place at the bank, according to an internal memo.  On Tuesday, senior executives from Europe's largest bank will testify before a Senate subcommittee to discuss what went wrong with the compliance efforts inside the bank that failed to defect potential money laundering activities.  [See Who's News story, "HSBC Money Laundering Ties".] "We will acknowledge and apologize for our past mistakes.  Our anti-money laundering controls should have been stronger and more effective, and we failed to spot and deal with unacceptable behavior." -- CEO Stuart Gulliver, in the memo, as confirmed by an HSBC spokesman. " Going Forward. In addition, the Senate hearing will also give bank officials to present the steps that HSBC has taken to improve its internal risk management, Mr. Gulliver said, who is not expected to testify.  In the past 2 years, the bank has doubled its compliance budget to $400 million.