Wall Street futures edged lower pre-bell Wednesday as traders reviewed Middle East turmoil, rich tech-sector valuations and awaited fresh catalysts.

In the futures, the S&P 500 fell 0.2%, the Nasdaq declined 0.4% and the Dow Jones was off 0.2%.

Federal Reserve Chairman Kevin Warsh is slated to appear on policy panel at the European Central Bank's annual forum in Portugal, at 9 am ET.

Asian exchanges traded unevenly higher overnight on tech strength, while European bourses tracked moderately lower midday on the continent.

FMC (FMC) traded up 6.1% pre-bell after the agriculture and chemical concern said it has agreed to sell $400 million of stock at $13.30 a share to the Belgium-based Tessenderlo Group, giving it a 20% stake in FMC.

General Mills (GIS) plans to report earnings pre-bell, among others.

On the economic calendar is the weekly MBA mortgage applications bulletin at 7 am ET, followed by the ADP employment report for June at 8:15 am.

The weekly jobless claims report logs at 8:30 am, followed by the final S&P Global manufacturing purchasing managers index (PMI) for June at 9:45 am.

The ISM manufacturing index for June, and the construction spending bulletin for May, post at 10 am.

The weekly EIA petroleum status report follows at 10:30 am.

In pre-market action, bitcoin traded at $58,644, West Texas Intermediate crude oil traded down 1.1% at at $68.77 a barrel, and 10-year US Treasuries offered 4.46%. Spot gold commanded $3,992 an ounce.