Negative yields could last through 2020, Vanguard exec says.

Flight to quality means flight away from government bonds in Eurozone, except Germany.

Flight to quality means flight away from government bonds in Eurozone, except Germany.

Currency weakens on BOJ governors comments and G-20s lack of opposition to Japanese policies.

Currency weakens on BOJ governors comments and G-20s lack of opposition to Japanese policies.

Italian debt also advances after auction.

Italian debt also advances after auction.

Bond purchases could lower yields, but alienate key policy makers.