European shares were flat on Wednesday, as investors stayed on the sidelines ahead of an all-important interest rate decision by the U.S. Federal Reserve that could mark the beginning of a monetary easing cycle in the world's largest economy.

Two prominent economists warn that the Federal Reserve reversing course now would be a "disaster" for markets and the greater economy, as inflation may be higher than they think.

SolarEdge Technologies is down 5% after shares of the solar-power-equipment maker were downgraded to Underperform from Hold at Jefferies and the price target cut to $17 from $27. S&P 500 futures are up 0.3%. Dow Jones Industrial Average futures are adding 0.2%.

Mostly tight-lipped on the Fed, Harris responded to Trump’s initial insinuation in August by reaffirming the Fed as an “independent entity” and vowing to “never interfere in the decisions that the Fed makes” if elected president.

The Fed will announce its interest rate decision on Wednesday. Nearly all expect them to cut rates because of weakening signs in the economy.

U.S. stock index futures edged higher as investors awaited a batch of economic data and clung to hopes the Federal Reserve would deliver a supersized interest-rate cut at its monetary policy meeting,

Investors and economists will find out on Wednesday whether the Federal Reserve sees the greater risk to the employment or inflation side of its dual mandate. The [ever-shifting odds](