From a Rolling Stone article --
The banks' laundering transactions were so brazen that the NSA probably could have spotted them from space. Breuer admitted that drug dealers would sometimes come to HSBC's Mexican branches and "deposit hundreds of thousands of dollars in cash, in a single day, into a single account, using boxes designed to fit the precise dimensions of the teller windows."[0]
[0] http://www.rollingstone.com/politics/news/outrageous-hsbc-se...