Hasta La Vista, Mexican Peso

 | Nov 29, 2014 11:43PM ET

Before I even begin, allow me to define terms. Being bullish on the USD/MXN (spot) is the exact same thing as being bearish on the Mexican peso (which is actually expressed as MXN/USD in futures trading). USD/MXN expresses the number of pesos per USD. MXN/USD is the value of the peso in dollar terms.

As I write this, the USD/MXN is trading at 13.750X, or 13.75 pesos per one USD. The MXN/USD trades at a reciprocal of USD/MXN. Thus, 100 divided by 13.750 equals $.07273, meaning that a peso is worth just over 7 cents.

When I stared trading currencies at the IMM in the 1970s the peso was worth about $.8006. Thus, in just shy of 40 years the peso has declined in value against theUSD by 90%. The chart below reflects MXN/USD.