Investors are turning to the commodities markets as a store of wealth. ETF funds own futures contracts, not physical commodities and trading futures comes with a “roll cost.” Investors do not want to take physical delivery, so they roll them from one contract to the next before they expire. Oil price of -$37 showed how extreme the roll cost can get.

Concerns start to grow among analysts over the longer-term inflation outlook. A collapse in real yields on bonds is driving record rallies in assets from gold to technology stocks. The yield on 10-year inflation-linked US government bonds sank below -1%. But ever greater levels of Fed stimulus are required just to prevent risky assets from falling.