The U.S. dollar extended its slide against other major currencies on Monday, the latest sign that investors may be starting to shun what has long been the safest haven in global financial markets.

An index that tracks the dollar against a basket of major trading partners fell for a fifth straight day, even as U.S. stocks and bonds rallied. The dollar has fallen by roughly 8% this year, trading near a three-year low.

There has been a particularly steep decline since President Donald Trump announced tariffs on nearly every country’s imports a few weeks ago. The dollar has lost value against the euro, the yen, the pound and a host of other currencies, making imports from those countries more expensive for Americans, even before tariffs are applied.

Investors and many of Trump’s advisers had expected the dollar to strengthen as tariffs were put in place, given the conventional wisdom that the levies would discourage Americans from purchasing imported goods and in turn reduce the demand for foreign currency. Treasury Secretary Scott Bessent argued that the dollar’s appreciation would be significant enough to offset a rise in inflation.

But the magnitude of the tariffs that Trump has announced has been more substantial than many expected, unleashing turbulence acute enough to raise questions about whether U.S. assets have lost their luster. On multiple days in recent weeks, when the dollar was selling off, so too were U.S. stocks and government bonds, a combination that Krishna Guha, vice chair at Evercore ISI, described as “rare, ugly and worrying.”

In part, the turmoil reflects the confusion about Trump’s plans for tariffs. Mixed messages about exemptions and pauses, and which products and countries might be hit with new tariffs, have rattled investors who have long seen dollar-denominated assets such as U.S. Treasury bonds as the surest thing in finance.

“Both institutional investors and central banks are having to begin to think about what would happen should the dollar and the Treasury market no longer be the safe haven,” said Joe Brusuelas, chief economist at the consulting firm RSM.

Sharp moves in the value of the dollar can have a destabilizing effect on the global economy, because it serves as a central pillar of the financial system. The dollar is on one side of nearly 90% of all foreign-exchange trades, according to the Bank for International Settlements, from Americans abroad using their credit cards to large corporations making billion-dollar takeovers. Essential commodities, such as oil, are also typically priced in dollars, regardless of who is buying or selling.

Brad Setser, a senior fellow at the Council on Foreign Relations who previously worked at the Treasury Department, said there were reasons not to read too much into the dollar’s sell-off.

For nearly a decade, U.S. assets have been among the best performers in the world — consider the “Magnificent Seven” tech stocks that propelled the S&P 500 and Nasdaq to a series of record highs.