NEW YORK — It was a scary good year for investors.
It was scary because the U.S. stock market plunged to several historic drops on worries about everything from President Donald Trump's tariffs to interest rates to a possible bubble in artificial-intelligence technology. In the end, though, it was a great year for anyone with the stomach to stick through the swings.
S&P 500 index funds, which sit at the heart of many savers' 401(k) accounts, returned more than 18% in 2025 through Dec. 11 and set a record high that day. It's their third straight year of big returns.
Here's a look at some of the surprises that shaped financial markets along the way:
Tariff tremors
Trump dropped the biggest surprise on ''Liberation Day'' in April, when he announced a sweeping set of tariffs that were more severe than investors expected.
It immediately triggered worries about a possible recession and spiking inflation. The S&P 500 plunged nearly 5% on April 3 for its worst day since the 2020 COVID crash. The very next day, it dropped 6% after China's response raised fears of a tit-for-tat trade war.
The tariffs' impact went beyond the stock market. The value of the U.S. dollar fell, and fear even shook the U.S. Treasury market, which is seen as perhaps the safest in existence.