Resumen:
The impact of COVID-19 on water-related equity indices is analyzed in this paper for different regions around the world by using fractionally integrated methods and an artificial neural network model. Using fractional integration, a lack of mean reversion is observed in all cases except in the USA, which means that, for these regions, a change in the trend will be permanent after COVID-19 unless additional measures are implemented. At the same time, a structural break is observed in all cases between the 4th and March 10, 2020, likely due to the drastic lockdown imposed in many if not most countries. Long memory was tested for the post-break period and mean reversion was found not only in North America but also in Europe. Moreover, the results were strongly aligned with those obtained using the neural network model. This suggests that the water-related equity indices and associated levels of investments in water and related utilities have moved back to their pre-Covid-19 levels.
