several of Mexico's banks collapsed amidst widespread mortgage defaults. The Mexican economy experienced a severe recession and poverty and unemployment increased. Precursors With 1994 being the final year of his administration's sexenio (the country's six-year executive term limit), then-President Carlos Salinas de Gortari endorsed Luis Donaldo Colosio as the Institutional Revolutionary Party's (PRI) presidential candidate for Mexico's 1994 general election. In accordance with party tradition during election years, Salinas de Gortari began an unrecorded spending spree. Mexico's current account deficit grew to roughly 7% of GDP that same year, and Salinas de Gortari allowed the Secretariat of Finance and Public Credit, Mexico's treasury, to issue short-term peso-denominated treasury bills with a guaranteed repayment denominated in U.S. dollars, called "tesobonos". These bills offered a lower yield than Mexico's traditional peso-denominated treasury bills, called "cetes", but their dollar-denominated returns were more attractive to foreign investors. Investor confidence rose after the North American Free Trade Agreement (NAFTA) was signed. Upon NAFTA's entry into force on January 1, 1994, Mexican businesses as well as the Mexican government enjoyed access to new foreign capital thanks to foreign investors eager to lend more money. International perceptions of Mexico's political risk began to shift, however, when the Zapatista Army of National Liberation declared war on the Mexican government and began a violent insurrection in Chiapas. Investors further questioned Mexico's political uncertainties and stability when PRI presidential candidate Luis Donaldo Colosio was assassinated while campaigning in Tijuana in March 1994, and began setting higher risk premia on Mexican financial assets. Higher risk premia initially had no effect on the peso's value because Mexico had a fixed-exchange rate. Mexico's central bank, Banco de México, maintained the peso's value through an exchange rate peg to the U.S. dollar, allowing the peso to appreciate or depreciate against the dollar within a narrow band. To accomplish this, the central bank would frequently intervene in the open markets and buy or sell pesos to maintain the peg. The central bank's intervention strategy partly involved issuing new short-term public debt instruments denominated in U.S. dollars. They then used the borrowed dollar capital to purchase pesos in the foreign exchange market, which, in turn, caused the peso to appreciate. The bank's purpose in mitigating the peso's depreciation was to protect against inflationary risks of having a markedly weaker domestic currency, but with the peso stronger than it ought to have been, domestic businesses and consumers