What is a negative interest rate bond?
It is by definition a default.
Just because it is an agreed upon default doesn't change that fact.

And that's at nominal rates. If there is any price inflation at all (and there is), that just adds to the losses.

A few days ago the European Central Bank suggested that it was about to cut interest rates.
This planned cut is happening at a time when Denmark is offering to lend money at MINUS 0.12% for a ten-year mortgage.
In other words, the bank would PAY YOU to take out a loan.

Sometimes a bubble is hard to recognize until after it has burst.
Sometimes it is easy to see.

In 1637 a single tulip bulb in the Netherlands was traded for a 12 acre farm, or 10 times the annual income of a skilled tradesman.
That's clearly a bubble.

So is this.

Central banks are increasingly turning to experimental monetary policy to deal with stagnant economic growth and the danger of deflation. If things keep going in the same direction, it'll soon come to America.