The idea that the spread between yields on nominal and inflation-indexed bonds measures expected inflation assumes that differences between them are due solely to inflation. In practice, that is not the case: the market for indexed bonds is smaller and much less liquid.
This suggests that nominal bonds are more attractive in episodes of financial stress when market participants put a premium on liquidity. Thus, when markets come under stress, the yields on indexed bonds rise to compensate for their relative illiquidity. Breakeven inflation therefore spuriously appears to fall when financial market tensions rise. Might this effect be so large as to impair the information content of breakeven inflation?
To explore this question, the figure below shows the VIX (inverted scale) together with 10-year breakeven inflation. Importantly, the surge in the VIX in the spring of 2020 as the covid pandemic struck seems associated with a collapse of breakeven inflation. And as the VIX declined, breakeven inflation rose as financial market tensions subsided. The figure thus suggests that part of the recent increase in breakeven inflation reflects a normalisation in financial markets since last spring rather than an increase in expected inflation.
Source: FRED