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April 30 (Reuters) - U.S. stock index futures were flat to slightly lower on Wednesday as investors braced for a spate of economic data and corporate results to close a turbulent month for financial markets.

First-quarter gross domestic product data, March's reading of the PCE price index - the Federal Reserve's preferred inflation metric - and ADP employment figures are all due on the day.

The U.S. economy is expected to have stalled or even contracted in the first quarter, with economists sharply downgrading estimates after data on Tuesday showed the goods trade deficit surged to an all-time high in March.

A series of data releases over the month has indicated an increasingly murky economic outlook and a sharp decline in business and consumer sentiment , underscoring the fallout from the rapidly changing U.S. tariff policy.

Caterpillar Inc CAT.N is among the many companies reporting results before the bell, while "Magnificent Seven" members Meta Platforms META.O and Microsoft's MSFT.O results will take the spotlight after markets close as investors await clarity on the outlook for the tech sector and AI-focused investments.

Fanning concerns about a pullback in investments into AI, Super Micro Computer SMCI.O cut its third-quarter forecasts due to delays in customer spending.

Several companies have cut or even withdrawn annual forecasts due to tariff uncertainty over the past weeks, with Snap SNAP.N one of the latest to pull its second-quarter outlook.

Shares of the Snapchat parent dropped 13.3%, while Super Micro Computer slumped 15.1% in premarket trading. Microsoft edged 0.2% higher and Meta Platforms fell 0.5%.

At 5:25 a.m. ET, Dow E-minis YMcv1 were up 5 points, or 0.01%, S&P 500 E-minis EScv1 were down 8 points, or 0.14%, and Nasdaq 100 E-minis NQcv1 were down 48 points, or 0.24%.

Indexes have recouped some ground this month after a sharp slump following the April 2 "Liberation Day" tariff announcements.

The Nasdaq Composite .IXIC is set for monthly gains of 0.9%, while the S&P 500 is on pace to slip about 1% and the Dow to lose over 3.5% in April.

The S&P 500 notched its best winning streak since November on Tuesday, but intraday trading has been choppy over the past few sessions as investors assess rapid trade developments. President Donald Trump signed a pair of orders to soften the blow of auto tariffs on Tuesday.

Wednesday also marks 100 days since Trump took office. Erratic changes in trade policies and uncertainty have roiled markets over that period, offsetting initial optimism over the administration's business-friendly policies.

The benchmark S&P 500 .SPX has lost more than 7% since Trump's presidency began, and is off over 9% from its February record close.

(Reporting by Lisa Mattackal in Bengaluru; Editing by Devika Syamnath)

((LisaPauline.Mattackal@thomsonreuters.com;))