Ackman's investing style has been praised and criticized by U.S. government officials, heads of other hedge funds, various retail investors, and the general public.[citation needed] His most notable market plays include shorting MBIA's bonds during the financial crisis of 2007–2008, his proxy fight with Canadian Pacific Railway, and his stakes in the Target Corporation, Valeant Pharmaceuticals, and Chipotle Mexican Grill.[citation needed] From 2012 to 2018, Ackman held a US$1 billion short against the nutrition company Herbalife, a company he has claimed is a pyramid scheme designed as a multi-level marketing firm.[66] His efforts were reported in the documentary film Betting on Zero.[67]