A trader works on the floor at the New York Stock Exchange (NYSE) in New York City, U.S., September 22, 2025. REUTERS/Jeenah Moon

(Reuters) -U.S. stock index futures slid on Wednesday as investors assessed the fallout from the federal government shutdown, which threatens to delay key economic data and muddy the central bank's policy-easing plans.

The risk-off sentiment reflects investor unease over what analysts have warned could be a prolonged impasse, driven by deep partisan divisions in Washington.

Markets are leaning heavily into hopes of a dovish Fed policy to sustain the rally that led equities to their second straight quarter of gains on Tuesday.

"While a government shutdown is disruptive in its own ways, now isn't exactly the time that investors or the Fed want to lose access to key economic data points," said Bret Kenwell, U.S. investment analyst at eToro.

Shutdowns have not derailed markets historically - the S&P 500 rose during each of the last six government shutdowns, according to a note from Deutsche Bank.

However, the current episode coincides with elevated stock valuations and a fragile mood.

Prolonged shutdowns also amplify risks. In the seven instances when they lasted 10 or more days, the index fell four times and rose thrice, according to data from Vanguard.

At 05:39 a.m. ET, Dow e-minis were down 230 points, or 0.49%, U.S. S&P 500 E-minis were down 36.75 points, or 0.55%, and Nasdaq 100 E-minis were down 157.25 points, or 0.63%.

The nonfarm payrolls report, scheduled for release on Friday, now seems likely to be delayed. It would be a setback for investors hoping for benign data to support a 25-basis-point Federal Reserve rate cut.

With uncertainty around release time, the ADP National Employment Report and the Institute for Supply Management's manufacturing PMI for September, due on Wednesday, will likely be scrutinized for clues on the labor market as well as inflation.

The shutdown could also jolt the labor market if federal agencies resort to mass layoffs, as President Donald Trump has vowed to do.

"Headlines about potential permanent layoffs linked to the shutdown add a low-probability, high-impact tail risk that could nudge unemployment higher," said Daniela Hathorn, senior market analyst at online trading company Capital.com.

Additionally, investors will parse commentary from Federal Reserve Bank of Richmond President Thomas Barkin for any shift in tone as policymakers navigate an uncertain data landscape.

Nike was among the early movers, rising 3.1% in premarket trading a day after reporting surprise revenue growth in the first quarter.

NYSE-listed shares of Lithium Americas surged 31% after it said the U.S. Department of Energy had taken a 5% stake in the company.

Enanta Pharmaceuticals and AAR Corp fell 12.3% and 6.8%, respectively, after pricing their stock offerings.

(Reporting by Niket Nishant in Bengaluru; Editing by Mrigank Dhaniwala and Pooja Desai)