How is carry trade considered profitable?

<p id="isPasted">For those who wish to dig a bit deeper into this puzzle, it's good to quickly review what academics and practitioners have said. First, reviewing decades of data on carry trades, they repeatedly find a risk premium, despite efficient market theories leading one to believe that, all things being equal, the tendency for high-interest currencies to appreciate more (or depreciate less) than what interest rate parity would predict shouldn't exist.</p><p>Here are some explanations given for this:</p><p><strong>Risk premia</strong>: Investors may demand more to hold certain currencies, beyond interest rate differentials. This could be because of perceived economic or political risks that can't be priced into simple interest rate differences. However, this is just another way of restating the puzzle, not answering why it exists.</p><p><strong>Central bank policies</strong>: Interventions or anticipated policy changes can influence currency demand in ways not captured by interest rates alone.</p><p><strong>Institutional factors</strong>: Similarly, large institutions may have specific needs or mandates that cause them to buy or sell currencies in patterns that don't align with interest rate parity.</p><p><strong>Behavioral factors</strong>: Investors engage in herding behavior or overreact to certain types of news, creating persistent biases in currency flows.</p><p><strong>Market microstructures</strong>: The way trades are executed and information flows through the market creates persistent patterns in order flow (supply and demand). A 2024 study, updating previous work, makes the vital contribution of showing that forward bias only exists in specific markets (mainly when interest rate differentials are positive) and isn't a universally applicable rule. This is crucial for investors involved in carry trades to understand.</p><p><strong>Global imbalances</strong>: Long-term capital flows because of trade imbalances or investment patterns often put sustained pressure on certain currencies.</p><p>Negative interest rate differentials correlate to crisis periods: When the typically higher interest rate currency goes lower than the other, these tend to be during economic and market crises. At these moments, there tends to be a flight to security, and the forward bias reverses itself.</p><p>When carry trade regimes change, events move fast: Studies find that transitions between positive and negative interest rate differential regimes are frequently abrupt. This implies that, in practice, snap shifts are the rule, not the exception.</p>