About $1 trillion of bonds have seen their yields turn negative this week, meaning 27% of the world’s investment-grade debt is now sub-zero. Bond bulls got a boost on Thursday when the European Central Bank boosted its asset purchase program by an additional 500 billion euros in a bid to support the region’s economic recovery.

Collapsing trading volumes are a worrying sign for the market’s future. European Central Bank has taken its purchases of debt to unprecedented levels. By the end of 2021, investors will be even more squeezed out. The ECB is set to own around 43% of Germany’s notes. Trading volumes in bund futures have collapsed 62%.