European markets closed higher on Wednesday, as news emerged that the European Central Bank is set to buy around 50 billion euros ($58.3 billion) per month of government bonds for around a year.
European stocks briefly spiked, before slipping to trade lower, after the Wall Street Journal cited sources in its report on the size of an ECB bond-buying program, which is widely expected to be announced Thursday.
The pan-European FTSEurofirst 300 provisionally ended around 0.5 percent higher after markets flipped between losses and gains for much of the afternoon session.
The executive board's proposal of at least 600 billion euro over the course of a year is above previous analyst forecasts of around 500 billion euro.
Earlier on Wednesday, ECB Governing Council member Ewald Nowotny advised investors against building overly high expectations about the outcome of a single policy meeting -- remarks that curbed enthusiasm about the likelihood of a large-scale bond-purchasing program earlier in the day.