So far, the Federal Reserve has avoided commenting on the increasingly uncertain outlook, but investors are waiting to see whether it changes its projections on Wednesday.

U.S. stock indexes are rising Wednesday after the Federal Reserve kept its main interest rate steady, as was widely expected. The S&P 500 was up 1.7% in afternoon trading, adding to its gains following the Fed's announcement.

Global shares were mixed Wednesday ahead of a decision on interest rates by the U.S. Federal Reserve. France's CAC 40 inched up less than 0.1% in early trading to 8,117.25, while the German DAX shed 0.