In a shocking decision 20 minutes to midnight, the ECB abruptly cancelled its acceptance of Greek bonds in return for funding, warning Athens for a reform deal.

Greek and Portuguese markets are attracting a fair number of yield-hungry investors, as the outlook for the bailed-out countries improves and alternatives look more expensive or increasingly risky.

The risk of investors having to accept more losses on Greek debt has abated following a writedown on the securities in 2012, according to Gareth Colesmith, a senior money manager at the London-based unit of Bank of New York Mellon, a leading company in global investments. The company was wary of Portuguese bonds because of the nation's struggle to implement fiscal reforms, he added.