The German five year Bund briefly slipping below the ECB's deposit rate of -0.40%, tecnically making it inelegible for its programm.
In the next few days there are some appointments that could be very destabilizing for the market:
23 June: Brexit
26 June: Spain elections.
The Bund is a "safeheaven", currently appears to be no more interesting return on capital, but the return of capital.