I just reflected on something that many traders don't fully understand: financial bicycles or carry trades. It's a strategy that sounds simple in theory but can be devastating if you don't know what you're doing.

Basically, the idea is to borrow money in a currency with very low interest rates (historically, the Japanese yen has been the favorite) and invest it in assets that pay much more. If everything goes well, you earn the difference between those rates. Sounds easy, right? The problem is that there are a lot of variables that can go wrong.

Let's take a classic carry trade example: for years, investors took out loans in yen at nearly 0% to put that money into U.S. Treasury bonds that paid 5.5% or more. It was like printing money. But in July 2024, the banca de Japón surprised everyone by sharply raising rates. The yen strengthened brutally, and that's where the chaos began.

What happened was that everyone who had leveraged positions in these trades had to close quickly. Imagine: you borrowed in yen, now that currency is worth much more, and you have to repay more money than you borrowed. It was a disaster. People started selling risk assets to pay their yen debts, and that sparked a wave of panic across global markets.

Currency risk is the main enemy here. If the currency you borrowed in increases in value, you lose. Fluctuations in interest rates can also derail your plans. In 2008, we saw brutal examples of how these trades can turn into a black hole of losses.

The reality is that it works well only when the market is calm and optimistic. But when there is volatility or uncertainty, everything becomes very risky very quickly. And if you also use a lot of leverage (borrowing much more than you have), moves against you are amplified exponentially.

This type of carry trade example is not for everyone. You need to deeply understand how global markets work, central bank decisions, and how to manage risk. That's why most of these traders are hedge funds and institutions with specialized teams.

My advice: if you don't have experience or you don't really understand what's going on, it's better to stay away. Gains can look attractive, but losses can be just as big—or worse. The market doesn't forgive ignorance.