The documents were downloaded by a former computer security expert at the giant bank HSBC. And they were released over the weekend by the International Consortium of Investigative Journalists.
The documents contain records of some 30,000 accounts kept at HSBC's Swiss subsidiary between 2005 and 2007. The accounts contained almost $120 billion and were tied to politicians, royalty, designers and sports figures in every part of the world. They were also tied to corrupt businessmen, dictators, arms industry officials and high-end criminals.
The records show bank employees actively helping customers conceal the accounts from authorities. The bank also provided bundles of cash in various currencies to customers so they couldn't be traced.
The cache of data was illegally downloaded by bank employee Herve Falciani, who later fled to France. Falciani told CBS's 60 Minutes Sunday night that he had help taking the data from other people at the bank.
"Friends, let's say, partners, gave me these data," Falciani says. "I'm not the only person in banking system that wants to raise alarm."
The documents release comes at a time when the secretive Swiss banking industry has been under investigation by the United States and other countries for helping its wealthy clients conceal their assets.
HSBC, which is one of the biggest banks in the world, was fined $1.9 billion by the U.S. government for money laundering in late 2012.
HSBC acknowledged after the documents were made public that its Swiss subsidiary committed wrongdoing. But the bank says it has since reformed its operations and now complies with international banking standards.