The 10-year benchmark Treasury yield fell to 1.814 percent after closing at 1.896 percent on Thursday. Thirty-year bonds yielded 2.387 percent, down from 2.54 percent before the ECB announcement and the close of 2.47 percent Thursday.
Italian and Spanish 10-year bonds fell to new record lows Friday, while the euro skidded to a fresh 11-year low against the dollar.
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In other news, Saudi Arabia's King Abdullah died early on Friday and his brother Salman has been named king. Investors will be keeping a close eye on the oil-exporting nation and what the succession means for crest-fallen commodity.
Heads of state and government join global business leaders for the third day of the World Economic Forum in the Swiss mountain resort of Davos. George Soros, U.K. Finance Minister George Osborne and German Finance Minister Wolfgang Schäuble are due to take part in a CNBC discussion on the future of Europe at 7 a.m. ET.
In equity markets, major fourth-quarter earnings on Friday include McDonald's, General Electric, Bank of NY Mellon, Kimberley-Clark,Honeywell and State-Street.