If you want to know how Donald Trump is doing, all you need to do is check the Mexican peso.

Over the past four months, Mexico’s currency has repeatedly declined when Trump’s election outlook improves and rallied when his odds of winning slump. The peso tumbled to a 2 1/2-month low Monday after his Democratic rival, Hillary Clinton, canceled a two-day trip to California because she’s suffering from pneumonia.

The presidential campaign has kept Juan Carlos Alderete busy. The 32-year-old head of currency strategy for Grupo Financiero Banorte SAB in Mexico City said phone calls from clients such as pension and mutual funds jumped 50 percent in July, when Trump improved his showing in predictive models like FiveThirtyEight during the Republican and Democratic conventions. Alderete has become a U.S. political junkie, closely following the daily movements and speeches of the two candidates -- particularly the one who pledges to end or overhaul Nafta and make Mexico pay for a $10 billion border wall.

"There’s not a lot of appetite to go long the peso given the risk for a Trump victory," said Alderete, who develops game plans for a team of currency and options traders at Mexico’s largest publicly-traded bank. "Among the different risk factors that affect all markets, this is one that could have greater consequences specifically for Mexico."