U.S. stock index futures fell Monday as worries persisted that the Trump administration's tariff policies could affect the world's largest economy, while EV maker Tesla declined following a bearish brokerage forecast.

At 6:40 a.m. ET, Dow E-minis were down 388 points, or 0.91%, S&P 500 E-minis were down 63 points, or 1.09%, and Nasdaq 100 E-minis were down 257 points, or 1.27%.

Megacap growth stock Nvidia lost 2% in premarket trading, while Meta and Amazon.com dropped more than 1.3% each.

Tesla fell 2.6% after brokerage UBS lowered its forecast for the automaker's first-quarter deliveries and cut its price target on the stock.

Futures tracking the more domestically focused smallcaps Russell 2000 index declined 0.9%, while investors flocked to safe-haven Treasury bonds.

In an interview on Sunday, President Donald Trump declined to predict whether the U.S. could face a recession, at a time when investors are concerned that his fluctuating trade policies on Mexico, Canada and China could dampen consumer demand and corporate investment.

China's retaliatory tariffs on some U.S. imports will take effect on Monday and U.S. tariffs on some base metals are expected to take effect later in the week.

Investors will also monitor U.S.-Canada relations. Former central banker Mark Carney won the race to become leader of Canada's ruling Liberal Party and will succeed Justin Trudeau as prime minister, according to official results.

A Reuters poll found 91% of economists view the odds of a downturn to have increased under Trump's rapidly shifting trade policies.

Amid this uncertainty, the benchmark S&P 500 logged its biggest weekly drop since September on Friday and the tech-heavy Nasdaq fell more than 10% from its December record high on Thursday. Since last week, the CBOE Volatility index has been at levels not seen since December.

Data on inflation, job openings and consumer confidence are due later in the week. The numbers could offer insights into the health of the economy and the U.S. Federal Reserve's monetary policy path.

On Friday, investors took some comfort from Fed Chair Jerome Powell's comments that the economy was on a strong footing, but he also underscored the need for caution on lowering borrowing costs.

The Federal Open Market Committee will convene next week and traders expect policy rates to be left unchanged for the first half of this year, according to data compiled by LSEG.

U.S.-listed Chinese stocks such as Alibaba fell 2.4%, Bilibili lost 4.4% and Xpeng declined 2.7% after data from China heightened concerns about a recovery in the world's second-largest economy.

Crypto stocks such as MicroStrategy slid 5.3%, Coinbase dropped 5.5% and Riot declined 4.3%, tracking a 4% drop in bitcoin.

Airbnb rose 1.8% after Jefferies upgraded the vacation home rental company's shares to "buy" from "hold."