The German 5-year bobl yield broken below zero.
That means if you buy one today and hold it until expiration, you’ll get less than you paid. You’d be better in cash.
It also means that buying US Treasuries instead looks like an awfully good deal and that will keep money flowing from euros into dollars and weighing on EUR/USD.
German Bobl
At the height of the crisis, there was chatter than the heavy bid in German debt included a breakup premium but it’s harder to make that argument now.