The banking giant HSBC "knowingly" provided support to four of Mexico's most notorious drug cartels by laundering their money and providing material support to terrorists, according to a new lawsuit filed by four families. The papers filed in U.S. District Court in Brownsville, Texas, on Tuesday say that laundering drug money made it possible for the cartels to operate. "HSBC's substantial and systemic money laundering support materially aided the activities of the Mexican cartels, including the Sinaoloa, Juárez, and Los Zetas cartels," court documents read.