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Through 2026 the headlines have been full of trouble: a war involving Iran, oil above $100, jumpy bond markets. You'd expect investors to run from everything. Yet the dollar index sits near 102, about 4% higher this year, while gold is roughly 6% below where it ended 2025. Why does the dollar tend to get stronger when the world gets nervous? Part of the answer is trust. Part is plumbing. And part of it, oddly, is that so much of the world owes money in dollars. Market figures are from around October 28, 2026.
When people get scared, they want something everyone accepts, and nobody doubts. The dollar fits that description better than anything else.
Central banks hold more than half of their foreign reserves in dollars. Oil, metals, and a lot of grain are priced in dollars too, and the dollar sits on one side of nearly nine out of ten currency trades. That makes it the common language of money. In a crisis, switching into the language everybody already speaks is the easy move.
The US government bond market is among the biggest and most liquid on earth. A pension fund or a central bank can put billions into Treasuries within hours and sell them just as fast. Few other places allow that. To buy Treasuries, investors first need dollars, so every wave of fear turns into a wave of dollar buying.
Fear alone doesn't explain the biggest moves. The plumbing does.
Companies and governments outside the US borrow heavily in dollars. When markets freeze, lenders pull back, and borrowers still have bills, interest payments, and margin calls to cover. They need dollars, and they need them now, whatever the price. That forced buying can lift the dollar sharply, even when nobody feels safe about anything.
Traders borrow one currency to buy something that pays more. When a scare hits, those positions get closed in a hurry, and the borrowed currency has to be bought back. If that currency is the dollar, the dollar jumps. The yen and the Swiss franc work the same way, which is why they sometimes spike at the same moment.
Currency strategists have a neat picture for all this, called the dollar smile. It says the dollar tends to rise at both extremes and sag in the middle.
| Stage | World Mood | Dollar’s Intent |
| Left side | Fear and crisis | Rises |
| Middle | Steady growth everywhere | Weakens |
| Right side | US economy outperforms, rates are high | Rises |
Both ends of the smile are in play. Fear from the Iran conflict and expensive oil sit on the left. High US rates sit on the right, with the Fed raising in September, holding at 3.75% to 4.00% on October 28 and markets leaning toward a hike in December. Even the yen, a classic haven, fell to its weakest level against the dollar since 1986 in June, because the gap in interest rates was so wide.
The pattern is common. It's not guaranteed.
In April 2025, the Liberation Day tariff announcement rattled markets, yet the dollar fell. Research published by CEPR argues that the dollar rises broadly and persistently only in severe funding stress, not in every scare. The tariffs hit confidence in US policy without causing a scramble for dollars, so investors looked elsewhere.
The dollar isn't the only refuge, and each one has its own weak spot.
| Safe-Haven | Why People Buy | Weak Spot |
| Dollar | Deep markets, reserve role | Can fall when the problem starts in the US |
| Yen | Japan holds lots of foreign assets | Wide rate gap in 2026 |
| Swiss franc | Neutral country, stable | Small market |
| Gold | Can't be printed, no issuer | Pays no interest, hurt by high rates |
A rising dollar isn't good news for everybody.
The dollar strengthens in uncertain times because it's the money the world already uses, backed by the deepest bond market, and because so many debts and trades need dollars when stress hits. It doesn't always work. When the trouble starts in the US, or when other havens offer something better, the dollar can slip. Right now, with high US rates adding to the fear, the pull toward the dollar is strong, though it may not last.
Is the US dollar a safe haven?
Often, but not always. It tends to rise in global scares, especially when borrowers scramble for dollars, though the yen, Swiss franc, and gold sometimes do better.
Why do investors buy dollars in a crisis?
It's the main reserve currency, Treasuries are easy to buy and sell, and many debts and trades need dollars.
What is the dollar smile?
A theory that the dollar rises in times of fear and when the US economy outperforms, and weakens when growth is steady worldwide.
Can the dollar fall during uncertainty?
Yes. If the problem starts in the US, or the scare doesn't create a dollar shortage, the dollar can slip, as it did in April 2025.
How does a strong dollar affect gold and oil?
Both are priced in dollars, so a stronger dollar makes them costlier for other buyers and often pushes prices down.
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