(Reuters) - Wall Street's main indexes were set for a mixed open on Friday, a day after Walmart's dour forecast hit sentiment, while UnitedHealth ( UNH ) slid after a report that the U.S. Justice Department is investigating the healthcare conglomerate.

UnitedHealth ( UNH ) dropped 11.4% in premarket trading after the Wall Street Journal reported that the U.S. Justice Department has launched an investigation into the company's Medicare billing practices in recent months.

Shares of other health insurers were also hit, with CVS Health down 4.9% and Humana losing 5.3%.

Walmart edged 0.2% higher after dropping more than 6% on Thursday - its biggest single-day decline in more than a year - after guiding sales and profit for the year below estimates, citing the need for caution in navigating an uncertain geopolitical landscape.

The retail giant's plunge, along with jitters around President Donald Trump's tariff threats and uncertainty over the Federal Reserve's interest rate outlook, led to declines in all three indexes.

"As long as the economy is strong, job market is strong and consumers stay resilient, then many of the president's policies will probably not be deleterious on the economy," said Jamie Cox, managing partner for Harris Financial Group.

"But if the consumer starts to falter, then it multiplies the difficulties of a tariff regime."

Earlier this week, Trump said he will announce fresh tariffs over the next month or sooner, adding lumber and forest products to previously announced plans to impose duties on imported cars, semiconductors and pharmaceuticals.

The S&P 500 is set for a flat weekly finish, receding somewhat after hitting all-time highs twice this week, while the Dow and the Nasdaq are on pace for mild weekly declines.

On Friday, preliminary February economic activity surveys published by S&P Global will be released at 9:45 a.m. ET, while the final reading of consumer sentiment calculated by the University of Michigan is due at 10 a.m. ET.

The Personal Consumption Expenditures (PCE) reading, the Fed's preferred gauge for inflation, would be on the radar next week after consumer and producer prices reading earlier this month painted a mixed picture.

Traders currently see at least one 25-basis-point interest rate cut by the Fed this year, with a 60% chance of an additional cut, according to LSEG data.

Several Fed officials on Thursday signaled they still feel that cooling U.S. inflation will in time allow the U.S. central bank to deliver further interest rate cuts.

Comments from Fed Vice Chair Philip Jefferson are due later in the day.

At 8:32 a.m. ET, Dow E-minis were down 233 points, or 0.53%, S&P 500 E-minis were up 2 points, or 0.03%, and Nasdaq 100 E-minis were up 78.75 points, or 0.36%.

Block slid 9.1% after the payment firm's fourth-quarter profit fell short of estimates.

Akamai Technologies dropped 9.5% as the cybersecurity company forecast annual 2025 revenue below estimates.