The most important factor is how large is the impact of the options trade? A larger HIRO reading indicates a more impactful options trade has just taken place. Second, how the trade was placed may determine its impact. An algorithmic sweep of the options market may have more impact than a trade done through a dealer desk. This is because when a trade is done through a desk the dealer may trade the hedge before printing the option. This can cause a value discrepancy between the chart and the cumulative indicator.