This paper investigates the degree of persistence of market fear in the VIX index over the sample
period 2004β2016, as well as some sub-periods. The findings indicate that its properties change
over time: in normal periods it exhibits anti-persistence, whilst during crisis period the level of
persistence is increasing. These results can be informative about the nature of financial bubbles
and anti-bubbles, and provide evidence on whether there exist market inefficiencies that could be
exploited to make abnormal profits by designing appropriate trading strategies