The serial correlation of high‐frequency intraday returns on the Italian stock index futures (FIB30) in the period 2000–2002 is studied. It is found that intraday autocorrelation is mostly negative for time scales lower than 20 minutes, mainly due to the bid–ask bounce effect. Although...

<Para ID="Par1">We introduce a unifying class of nonparametric spot volatility estimators based on delta sequences and conceived to include many of the existing estimators in the field as special cases. The full limit theory is first derived when unevenly sampled observations under infill asymptotics and fixed...</para>