The Peso in the Eye of the Storm

The Mexican peso has been the textbook "carry trade" currency for years: borrow money in a low-rate currency (dollars, euros, yen) and park it in pesos, which pay much higher rates. As long as the gap holds and the exchange rate doesn't move too much against you, you pocket the difference. Sounds simple — and for a long time, it was.

The spread that actually matters

Banxico has kept its reference rate well above the Fed's for years. That "spread" (the gap between the two rates) is basically the paycheck the market gives you for holding peso risk. When the spread is wide, the carry trade is juicy and money flows into Mexico. When it starts narrowing — because the Fed hikes or Banxico cuts — that cushion gets thinner, and the peso becomes more sensitive to any scare.

What happens when the Fed starts cutting?

Here's the subtle part: it's not just the level of rates, it's the direction. If the Fed starts cutting before or faster than Banxico, the spread can actually hold steady or even widen for a while — which, counter-intuitively, can keep favoring the peso. The problem shows up if the market starts pricing in that Banxico will also cut soon, and aggressively. That's when the carry trade starts feeling uncomfortable, because the "premium" for sitting in pesos shrinks right as global risk appetite might be shifting too.

The signal worth watching

You don't need to be an institutional trader to keep tabs on this. Two things are worth checking regularly: (1) Banxico's statement after each rate decision — the tone (hawkish or dovish) matters more than the number itself, and (2) how USD/MXN behaves on days of high global volatility (like when the VIX spikes). If the peso stays relatively calm on those days, that's a sign the carry trade is still healthy. If it starts swinging hard, that might be the first crack.

At Risk On we track both of these every day — that's why USD/MXN and the rate spread are part of the main dashboard.