The Dow Jones index broke through the 15,000 point threshold for the first time ever on Tuesday.
The European Central Bank (ECB) has cut interest rates to a new record low amid ongoing fears about the eurozone's economic health.
Bond managers have added to risk assets, while shorts on the yen hit a five-year high after the Bank of Japan (BoJ) announced radical monetary easing measures.
The worst of the eurozone debt crisis is over, according to Alliance Trust Investments' Fiona MacRae, as capital flows in the region start to reverse.